BATTERY CHARGER SERVICE SCHOOL

Transcription

1 BATTERY CHARGER SERVICE SCHOOL

2 Table of Contents Section Subject Pages 1. AC to DC Theory Basic Charging Principals Ferro-Resonant Design Advantages 1 4. Controls Component Testing Troubleshooting Flow Chart Schematics 1-10

3 AC TO DC THEORY A battery is a direct current device (D.C.), i.e. when compared to the zero axis, see figure 1. The battery voltage is always on one side, as illustrated in figure one. When a battery is discharged, the battery voltage decreases as the acid portion of the electrolyte is absorbed in the plates. In order to charge the battery, we must reverse this chemical action electrically. The electricity that we have available is alternating current (AC). See figure 2. As shown in figure 2, during half of the cycle, the alternating current is positive with respect to the zero axis. During the other half of the cycle, it is negative. In order to properly charge a battery, we must eliminate the negative portion of the cycle. In order to achieve this, we must rectify the AC voltage. Figure 3 illustrates a typical full wave rectified D.C. voltage. In order to achieve this, all standard battery chargers must employ a means of rectification, the simplest of which is a diode.

4 Figure 4 illustrates the electrical symbol for a diode, as well as the mechanical representation. A standard diode has two junctions - a "P" junction and an "N" junction. For our purposes, we will use the "Franklin Theory of Electricity". That is, current flows from positive to negative. When a positive voltage is applied to the anode of a diode with respect to the cathode, current will flow through the diode to the cathode. However, when a positive voltage is applied to the cathode with respect to the anode, no current will flow. Figure 5 illustrates the simplest form of rectification (single phase, half wave). In the A part of the sine wave, point "A" is positive with respect to point "B". As a result of this, current flows through the diode, through the battery and returns to point B. In the D part of the sine wave, point B is positive with respect to point "A", and the diode blocks the flow of current. The resulting sine wave is illustrated on the right.

5 Figure 6 illustrates a full wave center tap rectifier. In the A portion of the sine wave, point "A" is positive with respect to point "B" so current will flow through "A" diode, through the battery to point "B". It cannot flow through the "D" diode because of its blocking characteristics. In the D portion of the sine wave, point "D" becomes positive with respect to point "C". Current then flows through the "D" diode through the battery and returns to the C lead. The result is a full wave rectified D.C. illustrated at the right of the figure. Figure 7 illustrates a full wave bridge rectifier. In the A portion of the sine wave point "A" is positive with respect to point "D". Current then flows through the A diode through the battery, through A2 diode to point "D". In the D portion of the sine wave, point "D" is positive with respect to point A. Current then flows through the D1 diode through the battery through D2 diode and returns to point "A" producing the sine wave illustrated to the right of the figure.

6 Figure 8 illustrates the sine wave for 3-phase alternating current. Basically, 3 phase AC is simply 3 single-phase sine waves, superimposed 120 electrical degrees out of phase. In rectifying 3 phase power, we handle it as 3 single phase circuits. Figure 9 illustrates a 3 phase half-wave rectifier. In the A1 portion of the sine wave point A1 is positive with respect to point D1. Current then flows through the "A" diode, through the positive lead, through the battery, through the negative lead and returns to D1. In the A2 part of the sine wave, A2 is positive with respect to D2. Current then flows through the "A2" diode through the positive lead through the battery and returns through the negative lead to D2. For the A3 portion of the sine wave, the current flow is the same as in A1 and A2. Figure 10 illustrates a 3-phase full wave center tap rectifier. The current flow for each sine wave is exactly the same as that described in figure 6 for the single-phase center tap.

7 Figure 11 illustrates a 3-phase bridge type rectifier. The current flow per sine wave is the same as explained in figure 7, however, in the case of a 3-phase bridge, each diode is used as an "A" and a "D" diode as indicated. NOTE: In the case of the half wave and center tap type circuits, the phasing of the transformers is not critical because they are connected after the rectifiers. However, in the case of the 3-phase bridge, the transformer primaries and secondaries must connect exactly the same; e.g. start to finish, start to finish and start to finish.

8 Figure 12 illustrates the relationship of the charger voltage to the battery voltage. It should be noted that current flows only when the charger's output voltage exceeds that of the battery voltage (note: the charger's peak voltage is approximately 1.41 times the average voltage which is read by most standard meters). Figure 13 (curve "A") shows the relationship of a constant potential (voltage) charger to the battery voltage as it becomes charged. (Curve "B") illustrates the current characteristics produced by figure curve "A". Up to this point we have discussed converting AC to D.C. The second problem has become obvious in reviewing figures 12 and 13; that is, the voltage output of the charger is critical in determining the current to the battery. The standard AC input voltages available as listed on the left hand side of figure 14 are not suitable to charge the variety of the battery voltages listed on the right hand side of figure 14. Therefore, we must now employ a device that can change the AC input voltage available, to the proper D.C. voltage required by the battery. This device is called a transformer. Figure 14 illustrates the simplest type of transformer, one that consists of two coils, a primary and a secondary. In this basic transformer, electricity is converted into magnetism and then this magnetism is converted back into electricity. The relationship of the volts per turn of the primary will determine the volts per turn of the secondary. As an example, if

9 we apply 120 volts to a primary, which has 100 turns, and our secondary has 10 turns, the secondary voltage will be 12 volts.

10 Figure 15 illustrates the magnetic path employed in most EI type laminations. The primary and secondary are wrapped on the center core. Magnetic flux produced by the primary, flows through the center core, and returns through the outer legs of the transformer. Unfortunately, the simple transformer illustrated in figure 15 lacks some of the characteristics, which are desirable in a good charger design, such as regulation; controlled charging curve, high efficiency, high power factor, and "failsafe" performance. In order to achieve these features, in 1963, a special type of transformer was adapted for use in battery chargers. This transformer is called a ferro-resonant transformer. Figure 16 illustrates, a ferro-resonant transformer. In order to have more control over the characteristic of the secondary of this transformer, only a portion of the magnetic flux is allowed to flow under the secondary. The rest is diverted through a magnetic shunt. A third winding is employed to alter the flux characteristics in the secondary half of the transformer to product the desired magnetic characteristics to satisfy the features listed above. This third winding is call a capacitor winding because the component it is connected to is an oil filled capacitor. The function of the capacitor is to slow and thereby alter the wave shape of the magnetic flux under the secondary and condenser winding. By the change of the time voltage characteristics, the flux under the secondary winding is actually increased. By properly

11 designing the capacitor circuit, we can actually saturate the flux density of the secondary. This gives us very tight control over the charging characteristic the battery sees, without the use of delicate electronic components.

12 Figure 17 is an electrical wiring diagram for a ferro-resonant transformer. As you can see, the simple primary and capacitor windings are no longer simple in order to justify one more need of a good battery charger "versatility". Figure 18 illustrates the 4 basic types of primaries used. The first two are standard type "A" 120/208/240 and "B" 208/240/480. The third is a set voltage primary and the fourth is a set voltage with 120-volt tap. Figure 19 illustrates the three connections of our "A" type transformer.

13 Figure 20 illustrates the three connections of our "B" type transformer.

14 Figure 21 illustrates the connections of the capacitor winding and the adjustments, which would be used to increase or decrease the output if required.

15 BASIC CHARGING PRINCIPLES Discharge battery at six hour rate to 80% Depth of Discharge. Recharge using taper-curve charger. 1. Starting current is based on the amp-hour capacity of the battery, and the recharge time. 2. Taper to 4 to 6% of AH capacity of battery. 3. Affords optimum short-term charge. A. No excessive heating (120 F MAX). B. No electrolysis -(inefficient-gassing) based on AH law, which states charge rate less or equal to % amp hours removed. Water battery after 2.40 volts-per-cell point to prevent flooding and spillage. Cool battery down for 8 hours. Temperature effects charge current (cold elevates voltage; heat depresses voltage). Necessity of equalize charge (weekend); the necessity of which is dependent on battery usage. 1. Mixes electrolyte. 2. Balances voltages among cells.

16 OVER-CHARGING Wrong size charger 1. Too large a charger with no automatic control Charging too frequently 1. Equalizing too often 2. Opportunity charge Use of chargers that have no fail-safe means of shutdown Component failure may cause charger to lock up in high output.

17 UNDER-CHARGING Starting-rate current does not affect the battery from being under charged, UNLESS there is insufficient time to fully charge the battery. (Approximately 105 to 110 percent return). Starting rate current determines how long it will take to charge the battery. Finish rate current is critical to properly charging the battery. Finish rates on today s high counter-voltage batteries need to be higher than older designs. We suggest 4 amps per hundred amp-hour size of the battery AT 2.60 volts per cell. Typically, the finish rate charge from 80% state of charge to 108% fully charged will take approximately 3 hours. Force charging the battery beyond the 80% state of charge point will damage the battery. Not having sufficient output voltage at the end of the charge-cycle will prevent sulfation on the cell plates from being reversed.

18 FERRO-RESONANT DESIGN CHARGER ADVANTAGES Reliable - few parts. Good efficiency - 86% average. Excellent power factor - 95% average. High line-transient immunity on output. Current-limited output, built into the transformer. Any failure mode won't harm battery, always fails with a low or no output. Ideal for motive power taper-curve charging.

19 Control Feature Summary Charges flooded lead-acid batteries. Automatic start when battery is connected or manual start (if selected). Automatic stop when charge is finished. Fully charges partially discharged batteries without overcharging. Dead battery jump start for overly-discharged batteries. Equalize charge by user request or automatic equalize every 7 charges (if selected). Automatic refresh charging every 12 hours (if selected). Automatic shut-down if battery starts to overheat. Automatically resumes charge after a power failure (if auto-start selected). Displays charging amps during the charge cycle. End Voltage, end current, AH, and run time can be displayed at the end of charge or after disconnecting the battery. Delayed start adjustable from 0 to 12 hours in 10 minute increments (if auto-start selected). Displays code if an abnormal charge indication is detected. Cool down timer that shows elapsed time after the charge is complete (if selected). Simple dip switch setup for features and settings. Description The front panel has a 3 digit light-emitting-diode (LED) display which normally shows charging amps. This display also presents messages if an abnormal charge indication is detected. A green Charging indicator lights while the charger is charging. A yellow 80% Charged indicator lights when the battery is 80% charged. A green Battery Ready indicator lights when the charge is complete. A yellow Equalize indicator lights when an equalize charge is selected. A red Fault indicator lights if an abnormal charge indication is detected. The front panel has power on, power off, equalize on, and equalize off buttons. A charge can be stopped by pressing POWER OFF and resumed by pressing POWER ON. While charging, an equalize charge can be requested by pressing EQUALIZE ON and turned off by pressing EQUALIZE OFF. Operation The control is used in ferro-resonant taper chargers to provide fully automatic battery charging. The control has a charging profile that handles standard flooded lead-acid batteries. The charging profile, or algorithm, uniquely monitors the output current and voltage to optimally charge the battery, based on battery manufacturer s recommendations. The standard charging profile for flooded lead-acid batteries has 2 phases. During phase 1 the battery is charged at high current until the battery is 80% charged. Then phase 1 terminates and phase 2 begins. As the battery voltage rises during phase 2, charging current tapers down toward the finish rate current and the battery voltage starts to flatten out. Phase 2 ends and the charge is terminated when the battery voltage no longer changes. This termination method is called dv/dt-di/dt. The control offers several safeguards to protect the battery. If a wrong voltage battery is connected, the charger does not start and a Low-Battery-Voltage (F3) or High-Battery-Voltage (F4) message is displayed. While charging, if the battery voltage exceeds a profile-specific cut-off value, the charge terminates with an End-On- Voltage warning message (EnU followed by the end voltage in v/c). If the battery starts to overheat, the charge terminates with a Battery Too Hot (F2) error message. Normal Daily Charge When no battery is connected, the Charging indicator is off and the 3-digit display shows 0 amps. With the auto-start feature enabled, connecting a battery to the charger will cause it to begin a charge cycle. The charger will first perform a self-diagnostic test to verify the control is working properly. During this time a lamp test is performed causing all display segments and indicators to light. This allows the operator to observe any defective segments or indicators. When the self-diagnostic is complete, the charge starts if no delay is set, and the green Charging indicator lights. The display shows the charging amps to indicate the charger is in phase 1 of the charge cycle. If auto start is disabled, the display shows OFF. Press POWER ON to manually start the charge. When the battery is 80% charged, the yellow 80% Charged indicator lights and the charger starts phase 2 of the charge cycle.

20 When a charge is finished, the charger automatically turns off. The green Charging indicator and the 80% Charged indicator both go out and the green Battery Ready indicator lights. If cool down is enabled, the display shows elapsed time up to 24 hours in hh.m format where hh is hours, and m is the nearest 10 minute increment. If cool down is disabled or 24 hours has elapsed, the display shows 0 amps. Disconnecting the Battery Warning: Risk of explosion. Do not disconnect the battery while the charger is running. Hydrogen gas produced by the battery during charging can be ignited by arcing that occurs when the battery cable is disconnected. If the battery must be disconnected before the end of the charge cycle, the charger should be turned off first. Press POWER OFF, and verify the green Charging indicator goes out. The 3-digit display will show OFF. The battery may then be safely disconnected. If the green Battery Ready indicator is lit, the battery may be disconnected at any time. Equalize Charge Over time batteries can develop inequalities in cell charge. This can lower the effective capacity of the battery and shorten life. An equalizing charge re-balances the charge in the battery cells. Perform an equalize charge if any of the following conditions exist: 1. On flooded batteries the specific gravity of any cell at the end of charge is 20 points less than the average of all the cells. 2. The on-charge voltage of any cell at the end of charge is 20 millivolts less than the average of all the cells. 3. The battery has been stored for 30 days. The control can perform an equalize automatically every 7 charge cycles if auto equalize is enabled. Normal equalize consists of an additional 3 hour charge time at the end of a normal charge cycle. The control can also perform an equalize charge when requested manually. First connect the battery and allow the charge to start normally. Then press EQUALIZE ON. The yellow Equalize indicator will light. The charge time will be extended by 3 hours to allow the cells to equalize their charge. The auto-equalize or manual equalize cycle can be cleared by pressing EQUALIZE OFF while in the normal charge cycle. The yellow Equalize indicator will turn off. The next auto equalize charge will occur after another 7 charge cycles if auto equalize is enabled. If auto equalize is not desired, see dip switch settings for de-activating instructions. Delayed Start The delayed-start feature allows the operator to delay starting the charge cycle. This might be desired to reduce peak energy surcharges if the charger were ready to start during a peak energy period. The delay time could be set to keep the charger from starting until after the peak period ends. To view the delayed start setting, press EQUALIZE ON while the charger is not charging and hold for 3 seconds. The display shows dly followed by the current delay time in hh.m format where hh is hours and m is the nearest 10 minute increment. To change the delay time, press POWER OFF. The display shows hh._ where hh is the delay hours. Set the delay start hours using EQUALIZE OFF and EQUALIZE ON to scroll the value up or down. When the correct value is reached, press POWER OFF. The display then shows _mm where mm is the delay minutes. Set the delay minutes using EQUALIZE OFF and EQUALIZE ON to scroll the value up or down. When the correct value is reached, press POWER OFF to save the value. The display shows yes to indicate the value was saved. To exit the delay start programming mode at any time, press POWER ON. Any changes will automatically be saved and the display will show yes. While in the delay start programming mode, if no button is pressed for 10 seconds, the setting will automatically be saved and the display will return to the normal display of amps. The delay timer begins when a battery is connected. If a battery is already connected, it will be effective the next time a battery is connected. While waiting for the delayed start, the display shows dly and the hours and minutes remaining in hh.m format where hh is hours and m is the nearest 10 minute increment. If the auto-start feature is disabled, the delayed start is automatically set to 0 and is disabled. The delayed start time cannot be set.

21 Auto- Refresh Charge The control can provide an auto-refresh charge every 12 hours as long as the battery remains connected to the charger if enabled. If AC power is lost during the 12 hour wait period, the control will resume from where it left off after power is restored. During the auto-refresh charge, the amp-hours and charge time will be added to the original charge. When the charger is in an auto-refresh charge and the battery is 80% charged, the 80% LED will blink to indicate a refresh charge. If auto-refresh is not desired, see dip switch settings for de-activating instructions. Viewing Charge Information Additional charge information is available at the end of a charge cycle or after the battery is disconnected by pressing one of the four buttons. This information is retained after the battery is disconnected until the next battery is connected. After 10 seconds the display will return to the default display of amps. The following information can be viewed: BUTTON DISPLAY DESCRIPTION Power On UPC Battery voltage in volts per cell (v/c). (during charge) #.## Power On EnU Battery voltage at the end of charge in volts per cell (v/c). (after charge) #.## Power Off EnA Charging current at the end of charge. ### Equalize On AHr ##_ Accumulated amp-hours. The display will show the upper 2 digits (##_) followed by the lower 2 digits (_##). _## Equalize Off toc ##.# Time on Charge. The time is displayed in hh.m format where hh is hours and m is the nearest 10 minute increment. Power On and Power Off Simultaneously UEr #.## Software version. #.## indicates the version number. Note: The display does not have the ability to display the character V, so the character U is used.

22 Charge Indications The following indications are not necessarily a result of a charger problem. They are typically caused by external problems such as AC line, poor battery conditions, connections, etc. If abnormal charge conditions are detected, the charge is terminated, the red fault LED lights, and the display will show : DISPLAY DESCRIPTION POSSIBLE CAUSE F0 #.## Battery voltage did not reach 2.0 V/C within 30 minutes. #.## is the volts per cell at end of charge. - Shorted Cell - Open diode - Low Charging amps - Low AC line voltage - Wrong size battery - Battery over-discharged F1 #.## F2 F3 #.## F4 #.## Battery did not reach gassing voltage within 8 hours (16 hours if set for 16 hour mode). #.## is the volts per cell at end of charge. Hot battery. Detected by battery voltage dropping after gassing. Low battery voltage, less than 1.6 V/C at start up. #.## is the battery volts per cell. High battery voltage, more than 2.4 V/C at start up. #.## is the battery volts per cell. - Shorted Cell - Open diode - Low Charging amps - Low AC line voltage - Wrong size battery - Battery over-discharged - Battery is overheated - Wrong size battery - Battery over-discharged - S1 Dip switch setting incorrect - Wrong size battery - Battery fully charged - S1 Dip switch setting incorrect F5 No charging current to the battery. - Faulty AC line contactor - Open diode - Faulty resonant capacitor - Poor battery connections - Open cell - Faulty control board F6 Not Used F7 Long charge, the charger ran longer than 12 hours (20 hours if set for 16 hour mode) - Open diode - Low Charging amps - Low AC line voltage - Wrong size battery - Battery over-discharged F8 Charger stayed on when control requested it to shut off. - AC line contactor stuck on - Open shunt sense lead or loose connection - Faulty control board F9 Faulty keypad detected. One or more buttons are stuck on. - Faulty keypad - Faulty control board F10 Charging current exceeds 110% of shunt setting. - High charging amps - High AC line voltage - Incorrect shunt size - Open shunt sense lead or loose connection - Faulty control board

23 Note: F3 and F4 will clear automatically if the battery voltage falls within acceptable limits. All indications except F8, F9 and F10 can be cleared by disconnecting the battery. For F8, F9 and F10, correct the condition that caused the indication and disconnect the battery to clear the indication. CAUTION: If F8 is showing, and the charger is providing current to the battery, remove AC power from the charger before disconnecting the battery. F3 (Low Battery) Override If battery voltage is below 1.6 volts per cell the charger will not start automatically. If this is due to an overly discharged battery of the correct voltage, the F3 indication can be manually overridden by pressing POWER ON while the F3 message (Low Battery) displays.

24 Dip Switch Settings Figure 1. Dip Switches Switch S1 Position 1-8: DC Voltage Setting Pos 1 Pos 2 Pos 3 Pos 4 Pos 5 Pos 6 Pos 7 Pos 8 Volts ON V - ON V - - ON V ON V ON V ON V ON - 12V ON SP 3 Switch S2 Position 1-3: Shunt Setting Pos 1 Pos 2 Pos 3 Shunt ON OFF OFF 600A OFF ON OFF 500A ON ON OFF 400A OFF OFF ON 300A ON OFF ON 200A 1 OFF ON ON 100A ON ON ON 50A Position 4: Auto Start Pos 4 Function OFF Auto Start Disabled ON Auto Start Enabled 1 Position 5: Charge Hours Pos 5 Function OFF 16 Hour Mode ON 8 Hour Mode 1 Position 6: Cool Down Pos 6 Function OFF Cool Down Disabled 1 ON Shows Elapsed Time to 24 hours Position 7: Auto Equalize Pos 7 Function OFF Auto Equalize Disabled ON Auto Equalize Every 7 Cycles 1 Position 8: Auto Refresh Pos 8 Function OFF Auto Refresh Disabled ON Auto Refresh Every 12 Hours 1 1 Factory default settings. These apply to replacement controls shipped from stock. Verify that all settings are correct and match the particular charger before installing a new control. For new chargers, all parameters not specified on the order are set to the default settings. 2 12V setting may be used for voltages higher than 80V. A resistor is installed in the charger wiring harness based on the following calculation: R = 1250 x (Nominal Battery Voltage) Special setting used for non-standard battery voltages between 12V and 80V. Resistor R9 should be installed on the control based on the following calculation: R9 = 1250 x (Nominal Battery Voltage)

25 Display Summary 3 DIGIT STATUS DESCRIPTION ACTION DISPLAY LED S 0 None Charger ready for battery Connect Battery All On LED test. None required. bc None Battery connected. None required. Checking battery voltage. ### Charging ( Equalize ) ### Charging 80% Charged ( Equalize ) ### Charging 80% Charged blinking dly ##.# Coo ##.# EnU #.## None ( Equalize ) Battery Ready Charger on in phase 1. ### indicates charging amps. If Equalize is lit, charger will equalize at the end of the charge cycle. Charger on in phase 2. ### indicates charging amps. If Equalize is lit, charger will equalize at the end of the charge cycle. Charger refreshing. ### indicates charging amps. Charger in a delayed start mode. ##.# indicates the time until the start of charge in hh.m format where hh is hours and m is the nearest 10 minute increment. Charge complete. Battery cooling. ##.# indicates elapsed time from the end of charge in hh.m format where hh is hours and m is the nearest 10 minute increment. None required. Press Power Off to terminate the charge. Press Equalize On or Equalize Off to select/de-select equalize for the current cycle. None required. Press Power Off to terminate the charge. Press Equalize On or Equalize Off to select/de-select equalize for the current cycle. None required. Press Power Off to terminate the charge. None required. Press Equalize On or Equalize Off to select/de-select equalize for the current cycle. None required. The battery may be disconnected at any time. 0 Battery Ready Charge Complete. None required. The battery may be disconnected at any time. Battery Ready Charge Complete. Battery None required. voltage reached 2.80 v/c. The battery may be disconnected at any time. #.## indicates the voltage at the end of charge. Charge info Any Charger displaying charge information. Charge Fault An abnormal charge Indication condition has been detected None required. See section See section

26 INSTALLATION AND SETUP PROCEDURE CONTROLS WITH V4.xx SOFTWARE DESCRIPTION The charger control provides fully automatic battery charging in standard taper ferro-resonant chargers and in controlled ferro-resonant chargers. The control is powered from a 24VAC transformer that provides isolation from the AC service line. The presence of a battery is detected by the control and causes a charge cycle to begin automatically. The control has charging profiles that handle standard flooded, gel-cell, and sealed lead-acid batteries, as well as other battery types such as nickel-cadmium. Each charging profile, or algorithm, uniquely controls the output current and voltage to optimally charge a particular type of battery, based on battery manufacturer s recommendations. The control can be set to start charging at a certain time of day. It can be used with the I m Cool System and the TOBi Battery Management System. The display has three sections: MODE, DATA, and UNITS. The MODE display identifies the current state of the control. The DATA display shows a value, such as amps or volts/cell. The UNITS display shows the appropriate units for the value in the DATA display. A 16-key keypad allows the user to display various parameters and to customize the operation of the charger. INSTALLATION The control ships from the factory in an anti-static package. When opening the package, use normal precautions to prevent damage from static electricity. Before installation in the charger, the voltage selection dip switch (S1) must be set for the charger s rated voltage. Figure 1 shows the location of the battery voltage selection dip switch (S1) and the wire harness connection points. If the battery voltage is 12V, 24V, 36V, 48V, 64V, 72V or 80V, set the switch position marked with that voltage to on. If the voltage is higher than 80 volts, a factory installed attenuating resistor is in the charger wire harness and the voltage selection dip switch (S1) is set for 12V. If the voltage is between 12V and 80V but is nonstandard, then the dip switch is set on the SP (special) position. (NOTE: if the SP position is used, resistor R9 located next to S1 should have been installed at the factory. If it is not installed, contact the factory before proceeding.) The control is now ready to be installed in the charger. Disconnect the battery and AC service voltage. CAUTION: Lethal voltages are exposed when the charger is energized with the door open. Always disconnect the battery and the AC service voltage before opening the door for servicing. The control is mounted on the panel behind the keypad label. Connect the keypad ribbon cable to connector J7 on the control. Mount the control on the panel using the proper mounting screws and external-tooth lock washer. Connect the main cable harness to connector J2 on the control. If installing in a controlled ferro-resonant charger, connect the triac firing board cable to connector J3 on the control. If the charger is in an I m Cool system or a TOBi Battery Management system, install the communication cable to connector J6 on the control. Connect the AC service voltage to the charger, but do not connect a battery. The red RESET indicator on the control will light momentarily and then go out, and the software version number will appear in the display for about 2 seconds. Then the display will show OK 0 A. If the alert messages are turned on, a periodic no batt message will display every 10 seconds indicating that no battery is connected. PROGRAMMING Five parameters must be programmed for proper operation: 1) the time of day and date, 2) the algorithm, which is determined by the type of battery being charged, 3) the amp-hour rating of the battery which is obtained from the charger data plate, 4) the nominal battery voltage which is obtained from the charger data plate, and 5) the current shunt rating which is imprinted on the side of the current shunt located inside the charger. Gather this information before programming the control. Press the SET FUNC. key to enter the programming mode. The MODE display will show S1 and the DATA display will show SEt. Then another key or keys are pressed for the parameter to be programmed. The display will then show a brief description of the parameter and its current value. The parameter is changed by entering a new value using the numeric keys on the keypad. Data entry is from left to right. If more than four digits are entered, the left-most digits scroll off the left end of the DATA display. If an incorrect number is keyed in, press 0 four times to scroll the bad number off the display and continue entering the correct value. (Note that if no keys are pressed within about 8 seconds, the programming mode will time-out and the control will return to the normal OK 0 A display.)

27 Setting the Time-of-Day Press SET FUNC., and then press CLOCK. The MODE display will show TD for time of day. The DATA display will show tod= and then the time-of-day. The UNITS display will show HM for hours and minutes format. Time is entered in 24 hour format (military time). If the actual time is 3:27 PM, it is entered as Enter the correct local time using the numeric keys on the keypad. Press ENTER to save it. The display will show OK yes to confirm the new time was accepted. (If a time greater than is entered the display will show ER Err and then return to the normal OK 0 A display.) Setting the Date The date is set in 3 steps, first the month, then the day, then the year. Press SET FUNC., then 5, and then CLOCK. The MODE display will show MO for month. The data display will show JAn- dec 1-12 and the month, Enter the month using the numeric keys on the keypad and press ENTER to save it. If the month is accepted, the MODE display will then show DY for day-of-month. The data display will show day 1-31 and the day-of-month, Enter the day using the numeric keys on the keypad and press ENTER to save it. If the day is accepted, the MODE display will then show YR for year. The data display will show year and the year, Enter the year using the numeric keys on the keypad and press ENTER to save it. The display will show OK yes to confirm the new year was accepted. The control will then return to the normal OK 0 A display. Setting the Algorithm Refer to table 2 to determine which algorithm to use for your charger and battery type. If uncertain about which algorithm to use, contact the factory before attempting to program the control. Press SET FUNC., then 5, then START TIME. The MODE display will then show AL for algorithm. The data display will show CHrg ALg= and the algorithm number, Enter the algorithm using the numeric keys on the keypad and press ENTER to save it. The display will show OK yes to confirm the new algorithm was accepted. The control will then return to the normal OK 0 A display. Setting the Amp-Hour Rating Press SET FUNC., then 0. The MODE display will then show BS for battery size. The data display will show batt Ahr rat= and the battery size in amp-hours. The UNITS display will show AH for amp-hours. Enter the amp-hour rating using the numeric keys on the keypad and press ENTER to save it. The display will show OK yes to confirm the new amp-hour rating was accepted. The control will then return to the normal OK 0 A display. Setting the Battery Voltage Press SET FUNC., then 5, then 4. The MODE display will then show VR for voltage rating. The data display will show batt VLt rat= and the battery rating in volts. The UNITS display will show V for volts. Enter the voltage rating using the numeric keys on the keypad and press ENTER to save it. The display will show OK yes to confirm the new battery voltage was accepted. The control will then return to the normal OK 0 A display. Setting the Current Shunt Rating Press SET FUNC., then 5, then 5 again. The MODE display will then show SR for shunt rating. The data display will show CUrr SHnt rat= and the shunt rating in amps. The UNITS display will show A for amps. Enter the shunt rating using the numeric keys on the keypad and press ENTER to save it. The display will show OK yes to confirm the new current shunt rating was accepted. The control will then return to the normal OK 0 A display. Setting the Other Parameters If the charger is part of an I m Cool system or the TOBi Battery Management System then the charger identifier (ID) must be set. This and other additional parameters are programmed in a manner similar to that above. Table 1 describes the parameters and key-strokes used for programming them. When more than one parameter is in the same row of the table, the control automatically sequences through the additional parameters.

28 Table 1. Programmable Parameter List First Key Second Key Third Key Parameter(s) Description Allowable Settings Default Notes SET FUNCT. SET FUNCT. none none n/a n/a n/a SET FUNCT. 1 (DC AMPS) none SA Set Amps (A/100Ah) SET FUNCT. 2 (VOLTS CELL) none SV Set Volts (V) SET FUNCT. 3 (AH'S RT"ND) none CR Cable Resistance 0-25 (mω) 5 SET FUNCT. START TIME none TS Time of Day Start ; (disable) SET FUNCT. 4 (RUN TIME) none ST Set Charge Time SET FUNCT. 5 SET FUNCT. none n/a n/a n/a SET FUNCT. 5 1 (DC AMPS) WA Watering Enable 0 (disable); 1 (enable) 0 WC Watering Cycle Time SET FUNCT. 5 2 (VOLTS CELL) CV Charge Cutoff Voltage (v/c) SET FUNCT. 5 3 (AH'S RT"ND) EC Equalize by Number of Charges ED Equalize by Day 0(disable); 1-7(Sun-Sat) 0 2 DE Equalize Delay Time SET FUNCT. 5 START TIME AL Charge Algorithm 1-14 n/a 1 SET FUNCT. 5 4 (RUN TIME) VR Battery Voltage Rating (V) 24 SET FUNCT. 5 5 SR Charger Shunt Rating (A) in increments of SET FUNCT. 5 6 (CHGR. ID #) EM Equalize Mode 0 (None); 1(Normal) 1 2 EI Equalize Current (A/100Ah) SET FUNCT. 5 CLOCK MO Month 1-12 (Jan-Dec) n/a DY Day (of the month) 1-31 n/a YR Year 0-99 (years since 2000) n/a SET FUNCT. 5 7 (COOL DOWN) AR Automatic Refresh Enable 0 (disable); 1 (enable) 0 SET FUNCT. 5 8 (% RET'N) DS Delayed Start Time SET FUNCT. 5 9 (TRIP POINT) TP DVDT Trip Point (v/c) SET FUNCT. 5 ENTER N2 F2 Indication Disable 0 (enable); 1 (disable) 0 2 N3 F3 Indication Disable 0 (enable); 1 (disable) 0 2 N4 F4 Indication Disable 0 (enable); 1 (disable) 0 2 N6 F6 Indication Disable 0 (enable); 1 (disable) 0 2 SET FUNCT. 5 EQUALIZE ET Equalize Time SET FUNCT. 5 0 (LAMP TEST) AO Alert On Enable 0 (disable); 1 (enable) 1 AI Alert Interval (s) 10 SET FUNCT. 5 ON/OFF BC Battery Module Comm. Enable 0 (disable); 1 (enable) 0 SET FUNCT. 6 (CHGR. ID #) none ID Charger I.D. (for Tobi or I'm Cool) ; SET FUNCT. CLOCK none TD Time of Day (Clock) n/a SET FUNCT. 7 (COOL DOWN) none CT Cool Down Time TU Cool Time Count Up Enable 0 (count down); 1 (count up) 0 SET FUNCT. 8 (% RET'N) none CF Charge Back Factor (% of AH rating) 120 SET FUNCT. 9 (TRIP POINT) none OT OK to Charge Temp ( F) LT Low Charge Temp ( F) NT No Charge Temp ( F) SET FUNCT. ENTER none none n/a n/a n/a SET FUNCT. EQUALIZE none CU DVDT Periods 3-15 (5 minutes each) 5 SET FUNCT. 0 (LAMP TEST) none BS Battery AH Rating (Ah) in increments of 10 0 SET FUNCT. ON/OFF none AS Auto Start Mode 0 (off); 1 (on); 2 (on-ac) 1 Notes: 1. The Algorithm is set for the particular charger and battery type. If you are unsure of which algorithm to use, consult factory before setting. 2. These parameters are part of the algorithm. Any changes made to these will be overwritten whenever the algorithm parameter is set. 3. These parameters are only used for certain algorithms. Consult the factory before changing any unfamiliar parameters.

29 Table 2. Algorithm List Algorithm Battery Type Charger Type Algorithm Type Description 1 Flooded Lead-Acid Controlled Ferro Normal DVDT Phase 1: Constant current at the start rate until 2.38 v/c. Phase 2: Constant Voltage at 2.38 v/c until dvdt or the current falls to 4A/100Ah Phase 3: Constant Current at 4A/100Ah until dvdt. Phase 4: not used. Note: The start rate is set by pressing 'SET FUNC.', 'D.C. AMPS'. 2 Flooded Lead-Acid Ferro-Resonant Normal DVDT Phase 1: Full output until 2.38 v/c. Phase 2: Full output until dvdt. Phase 3: not used. Phase 4: not used. 3 Flooded Lead-Acid Ferro-Resonant Hysteresis Phase 1: Full output until 2.38 v/c. Phase 2: Full output until dvdt. Phase 3: Charger off until voltage drops to the hysteresis point, then reverts to phase 1. Phase 4: not used. Note: The hysteresis point is set by pressing 'SET FUNC.', '2'. It is entered as total battery voltage. 4 Champion Sealed Controlled Ferro Normal DVDT Phase 1: Constant current at 16.5A/100Ah until 2.37 v/c. Phase 2: Constant voltage at 2.37v/c until the current falls to 2.5A/100Ah or 5 hours. Phase 3: Constant current at 2.5A/100Ah until dvdt or 2.55v/c. Phase 4: Constant voltage at 2.55v/c until dvdt or 30 minutes. 5 Champion Sealed Ferro-Resonant Normal DVDT Phase 1: Full output until 2.37 v/c. Phase 2: Full output until dvdt or 2.52v/c. Phase 3: not used. Phase 4: not used. 6 Sonnenschein gel Controlled Ferro Special Phase 1: Constant current at 16.5A/100Ah until 2.35v/c. Phase 2: Constant voltage at 2.35v/c until the current falls to 1.3A/100Ah. Phase 3: Constant current at 1.3A/100Ah for 1 to 4 hours depending on time so far. Phase 4: not used. Note: Equalize will occur 10 hours after the charge at 0.6A/100Ah. 7 Deka gel Controlled Ferro Float Phase 1: Constant Current at 15.5A/100Ah until 2.33v/c. Phase 2: Constant voltage at 2.33v/c until the current falls to 0.3A/100Ah or 10 hours. Phase 3: not used. Phase 4: not used. continued

30 8 Saft Ni-Cad Controlled Ferro Special Phase 1: Constant current at 20A/100Ah until 1.59v/c or 6 1/2 hours. Phase 2: Constant current at 5A/100Ah until 15% more Ah are put in. Phase 3: not used. Phase 4: not used. 9 Flooded Lead-Acid AccelRate Pulse-Load Phase 1: Constant current at 50A/100Ah until 2.55v/c. Phase 2: Constant current at 30A/100Ah until 2.55v/c if time in phase 1 < 1 1/2 hours. Phase 3: Constant voltage at 2.55v/c until the current falls to 16.6A/100Ah or 3 hours total. Phase 4: not used. Note: A 12 second load at 5A/100Ah is applied every 2 minutes during charge. 10 Any Controlled Ferro Shop Charger Phase 1: Constant current at the start rate until the float voltage is reached. Phase 2: Constant voltage at the float voltage for the total run time. Phase 3: not used. Phase 4: not used. Note: The start rate, float voltage, and run time are set using 'SET FUNC' and '1', '2', or 4 respectively. 11 Geltec/Crown gel Controlled Ferro Special Phase 1: Constant current at 16A/100Ah until 2.40v/c. Phase 2: Constant voltage at 2.40v/c until the current falls to 1.5A/100Ah or 6 hours. Phase 3: Constant current at 1.5A/100Ah for the remainder of the 6 hours from phase 2. Phase 4: not used. 12 Flooded Lead-Acid Controlled Ferro AGV Trickle Charge Phase 1: Constant current at the start rate until 2.40v/c. Phase 2: Constant voltage at 2.40v/c until the current falls to 1A/100Ah or dvdt. Phase 3: Constant current at 4.5A/100Ah until 2.65v/c or 3 hours if manual equalize selected. Phase 4: Constant voltage at 2.25v/c as long as the battery is connected. Note: The start rate is set by pressing 'SET FUNC.', 'D.C. AMPS'. 13 Douglas VRLA Controlled Ferro Special Phase 1: Constant current at 16A/100Ah until 2.40v/c. Phase 2: Constant voltage at 2.40v/c until the current falls to 3A/100Ah or dvdt. Phase 3: Constant current at 3A/100Ah until dvdt or 2.70v/c. Phase 4: Constant voltage at 2.70v/c until dvdt. 14 n/a Any Factory Test Phase 1: Full output for 1 minute. Phase 2: Constant current at maximum regulation point for 1 minute. Phase 3: Constant current at minimum regulation point for 1 minute. Phase 4: Minimum output for 1 minute. Table 2. Algorithm List Continued.

31 OPERATION If alert messages are turned on, every 10 seconds a message will show for about 2 seconds in the display. With no battery connected, the control displays OK 0 A, and every 10 seconds a no batt alert is shown. When a battery is connected, a lamp test is performed and then the MODE portion of the display shows BC for battery connecting. Then the charge starts and the MODE portion of the display shows HC for high charge. The DATA display shows CHrG PH1 periodically along with the charging amps to indicate the charger is in phase 1 of the charge cycle. The UNITS portion of the display shows A for amps. If equalize is active, the UNITS portion of the display shows AE to indicate an equalizing charge is occurring. When phase 1 is completed, the charger starts phase 2 of the charge cycle. The MODE portion of the display shows LC for low charge. The DATA display shows CHrG PH2 along with the charging amps. The UNITS portion of the display shows A for amps (or AE if an equalize charge). Depending on the charger and battery type, the charger may utilize up to 4 phases to complete a charge. During the equalize portion of the charge cycle the DATA display shows EqU On periodically along with the charging amps. When a charge is finished, the charger automatically turns off. The MODE portion of the display shows EN for end. The DATA display shows End batt rdy. The UNITS portion of the display will be blank. The battery may then be disconnected at any time. EQUALIZE CHARGE Over time batteries can develop inequalities in cell charge. This can lower the effective capacity of the battery and shorten life. An equalizing charge re-balances the charge in the battery cells. Perform an equalize charge if any of the following conditions exist: 1. On flooded batteries the specific gravity of any cell at the end of charge is 20 points less than the average of all the cells. 2. The on-charge voltage of any cell at the end of charge is 20 millivolts less than the average of all the cells. 3. The battery has been stored for 30 days. The control can perform an equalize automatically based on the number of charge cycles or on a specific day of the week. Normal equalize consists of an additional 3 hour charge time at the end of a normal charge cycle. The control is set at the factory to perform a normal equalize every 7 charging cycles for flooded lead-acid batteries. The control can also perform an equalize charge when requested manually. Press the EQUALIZE key. The UNITS portion of the display will change from A to AE indicating an equalize charge will be performed on the current charge. If no battery is connected, the next charge time will be extended to allow the cells to equalize their charge. The auto-equalize or manual equalize charge can be cleared by pressing the EQUALIZE key again. The UNITS portion of the display will change from AE to A indicating a normal charge will be performed. The next auto equalize charge will occur after the programmed number of charge cycles.

32 CHARGE INDICATIONS The following indications are not necessarily a result of a charger problem. They are typically caused by external problems such as AC line, poor battery conditions, connections, etc. If abnormal charge conditions are detected, the charge is terminated, the MODE display shows ER for error. The DATA display shows the code: DISPLAY DESCRIPTION POSSIBLE CAUSE F0 SHrt CELL #.## Battery voltage did not reach 2.0 V/C within 30 minutes. #.## is the volts per cell at end of charge. - Shorted Cell - Open diode - Low Charging amps - Low AC line voltage - Wrong size battery - Battery over-discharged F1 SHrt CELL #.## F2 HOt BAtt F3 LO ULts #.## F4 HI ULts #.## F5 no CUrr F6 Chrg Err F7 LOng CHrg F8 CHrg On F9 bad PAd F10 HI CUrr Battery did not reach target voltage during phase 1. #.## is the volts per cell at end of charge. Hot battery. Detected by battery voltage dropping after gassing. Low battery voltage, less than 1.6 V/C at start up. #.## is the battery volts per cell. High battery voltage, more than 2.4 V/C at start up. #.## is the battery volts per cell. No charging current to the battery. Charger Voltage/Current not what was requested by control. (Controlled ferro chargers only) Long charge, the charger ran longer than the allotted time in the current phase. Charger stayed on when control requested it to shut off. Faulty keypad detected. One or more buttons are stuck on. - Shorted Cell - Open diode - Low Charging amps - Low AC line voltage - Wrong size battery - Battery over-discharged - Battery is overheated - Poor battery connections - Wrong size battery - Battery over-discharged - S1 Dip switch setting incorrect - Wrong size battery - Battery fully charged - S1 Dip switch setting incorrect - Faulty AC line contactor - Open diode - Faulty resonant capacitor - Poor battery connections - Open cell - Faulty control board - Open diode - Faulty resonant capacitor - Poor battery connections - Open cell - Faulty firing board - Faulty control board - Open diode - Low Charging amps - Low AC line voltage - Wrong size battery - Battery over-discharged - AC line contactor stuck on - Open shunt sense lead or loose connection - Faulty control board - Faulty keypad - Faulty control board Charging current exceeds 110% of shunt setting. - High charging amps - High AC line voltage - Incorrect shunt size - Open shunt sense lead or loose connection - Faulty control board

33 Note: F3 and F4 will clear automatically if the battery voltage falls within acceptable limits. All indications except F8, F9 and F10 can be cleared by disconnecting the battery. For F8, F9 and F10, correct the condition that caused the indication and disconnect the battery to clear the indication. CAUTION: If F8 indication is showing, and the charger is providing current to the battery, remove AC power from the charger before disconnecting the battery. F3 (LOW BATTERY) OVERRIDE If battery voltage is below 1.6 volts per cell the charger will not start automatically. If this is due to an overly discharged battery of the correct voltage, the F3 indication can be manually overridden by pressing POWER ON while the F3 message (Low Battery) displays. DISPLAYING ADDITIONAL CHARGE INFORMATION The user can view many different parameters associated with a charge. By pressing an appropriate key, information such as charger run time or amp-hours returned can be viewed. The display will time out after about 7 seconds and return to the default display which is usually amps. Display Software Version To display the software version number press 5. The display will show UEr followed by the software version number (e.g. 4.00). Display Charging Current In most applications charging current is normally displayed. However, on float utility chargers the battery voltage is generally the default display. If charging current is not already being displayed, press D.C. AMPS to view. The DATA display shows charging current in amps. The UNITS display shows A for amperes. Display Volts Per Cell To view volts per cell, press VOLTS CELL. The DATA display shows the volts per cell and the UNITS display shows VC for volts per cell. If the charge has finished and the battery is still connected, the end volts per cell is displayed. Repeatedly pressing the VOLT CELL key will toggle between volts per cell and full battery voltage. Display Full Battery Voltage To view battery voltage, press VOLTS CELL twice. The DATA display shows the full battery voltage and the UNITS display shows V for volts. Display Amp-Hours To view amp-hours returned to the battery, press AH S RT ND. The DATA display shows the amp-hours returned to the battery so far during the current charge. The UNITS display shows AH. Display Total Charger Amp-Hours (software v4.02 or higher)

34 To view the total amp-hours accumulated by the charger, press AH S RT ND twice. The DATA display shows the total amp-hours accumulated by the charger since the control was installed in 2 steps. The upper 4 digits are displayed with the right decimal point lit, followed by the lower 4 digits. For example, a display of followed by 5678 would indicated a total amp-hours accumulated of 12,345,678 Ah. The UNITS display shows AH. Display Time-of-Day Start Time To view the time-of-day start time, press START TIME. The DATA display shows the time-of-day start time in hours and minutes, and the UNITS display shows HM for hours and minutes format. The time-of-day is in 24-hour format. Thus a start time of 4:30PM would be displayed as If the time-of-day start is not active, the display shows Display Charger Run Time To view charger run time so far, press RUN TIME. The DATA display shows the run time in hours and minutes and the UNITS display shows HM for hours and minutes format. Display Charger Identification Number Chargers that are part of an I m Cool Battery Selection System or a TOBi Battery Management System have a unique identifying number. To view this ID number, press CHGR. ID #. The DATA display shows the charger ID number. If no number is set, the DATA display shows UNITS display is blank. Display Time of Day To view the current time, press CLOCK. The DATA display shows the time-of-day in 24-hour format. The UNITS display shows HM for hours and minutes format. Display Cool-Down Time To view battery cool down time, press COOL DOWN. The DATA display shows the cool down time setting in hours and minutes. The UNITS display will show HM for hours and minutes format. Display Percent Amp-Hours Returned To view amp-hours returned as a percentage of the battery size press % RET N. The DATA display shows the percentage of amp-hour capacity returned. The UNITS display will show % for percentage. Display Trip Point To view the cell voltage at which the battery is 80% charged, press TRIP POINT. The DATA display will show the 80% voltage as volts per cell. The UNITS display shows VC for volts per cell.

35 Perform Lamp Test To check the display for out segments press LAMP TEST. All segments in the display will light. ADDITIONAL KEYPAD FUNCTIONS The following additional keypad functions are available: F3 (Low Battery) Override Press ON/OFF while the F3 message (Low Battery) displays. Water Valve Test Verify the watering parameter WA is ON. Press 7 and ON/OFF simultaneously to toggle water valve on and off. If left on, valve turns off after 3 minutes. Reset Press 4, 5, and 6 simultaneously. Resets and restarts the processor. Load Default Values Disconnect battery. Press 1, 2, and 3 simultaneously. This removes all program changes and loads the default parameter values. The control displays ER and no ALg Set. The control must then be re-programmed as described in PROGRAMMING above.

36 Figure Control Layout

37 Components and Their Testing Resistors Resistors are used in electrical circuits to limit the current flow. The resistance of the device is measured in Ohms and is defined as the resistance through which a difference of potential of one volt will produce a current of one amp. The result in impeding current by the resistor yields power dissipation in the form of heat. Subsequently, there is another factor in selecting a particular resistor for an application; Wattage or physical size. There are other elements such as accuracy and failure rate. Larger sized resistors usually ceramic have their values printed on the body, however; resistors of wattage sizes of three watts or less usually have their values indicated on the body of the device with bands of colors. The following chart can be used in determining the value of color-banded resistors. 1st Digit 2 nd Digit Multiplier Tolerance Failure Rate COLOR A B C D E Black Brown ±1% 1.0 Red ±2% 0.1 Orange 3 3 1K ±3% 0.01 Yellow K ±4% Green K Blue 6 6 1MEG Violet MEG Gray MEG White Gold ±5% Silver ±10% No Color ±20% EXAMPLES COLORS OHMS A B C 100 Brown Black Brown 10 Brown Black Black 1.0 Brown Black Gold 0.1 Brown Black Silver

38 Capacitors A capacitor is used in electrical circuits to store electrical energy. It will block the flow of direct current, and permits the flow of alternating current to a degree dependent upon the capacitance and the frequency. The measure of capacitance of a capacitor is the Farad. This is a charge of one coulomb that produces a 1-volt potential difference between its terminals. A Farad is a large value for most practical electrical circuits, so the most common values seen would be micro-farads (abbreviated mfd. or µfd.). Besides a value of stored electrical charge, there is also another consideration to address. Capacitors also have a rating of the Voltage potential they can safely operate. The body of the capacitor usually displays both values. Refer to Fig. C for samples of various types of capacitors. There are two basic types of capacitors, the first being non-polarized which means that the capacitor can be used in either AC or DC circuits. This type of capacitor doesn't care which terminal sees the more positive potential. A polarized capacitor has to have the highest potential connected to the terminal marked positive or +. Polarized capacitors will fail if they are connected to reversed polarity in the circuit. Oil filled capacitors like the type used in ferro-resonant transformer circuits are non-polarized types.

39 Diodes A diode is classified in the semi-conductor family. It is a device that will allow electrical current to pass easily in one direction but blocks current in the opposite direction. Rectifier diodes are used in the output of the power transformer secondary to convert ac current into dc current. Diodes are rated or classified by their current (Amps) carrying capability, and their capability to withstand voltage that is applied in a reverse direction of current flow. This is classified as PRV (peak reverse voltage) or PIV (peak inverse voltage), they both mean the same. In some cases, a rectifier power diode can be purchased in two configurations; one where the Cathode of the diode is the stud (or case) and the Anode is the lead (or pigtail). The other configuration is where the Anode is the case (or stud) and the Cathode is the lead (or pigtail). Refer to Fig. D. Fig. D