Frequetly asked questios about battery chargers What factors should I cosider whe choosig a battery charger? 1. How may battery baks will you be chargig? Take ito accout mai, starter, bowthruster, etc. Also cosider ay possible future extesio of your system (= sufficiet battery charger outputs). 2. Battery charger must have the same voltage as the battery bak, i.e. 12 V battery voltage = 12 V battery charger. 3. To safely charge the batteries you eed to have the correct chargig curret (measured i amps). See the battery charger specificatios i this Powerbook for the recommeded capacity. 4. Compare the specificatios ad prices of the differet battery chargers based upo their capacity. Which battery charger is ecessary for a battery capacity of 200 Ah ad a 100 Ah starter battery? The starter battery is geerally ot cosidered whe calculatig the charger capacity - it is oly used for startig the egie ad will therefore ted to be oly partially discharged if at all. While you are usig the egie, the alterator recharges the battery ad whe coected to the grid, it is charged via the secod or slave output of the Mastervolt battery charger. As a rule, a charge capacity of 25% (up to 50% for gel batteries) of the battery capacity is sufficiet to charge the battery quickly ad safely, ad also power the oboard systems. For a battery of 200 Ah, for istace, a battery charger of 50 amps would be appropriate. The charge curret is stadard specified for the omial output voltage (12 or 24 V). Mastervolt applies a cosiderably higher output voltage of 14.25 or 28.5 V. This meas a shorter charge period ad faster rechargig of your batteries. What type of battery ca I charge? You ca easily charge all battery types, such as wet, AGM, gel ad Lithium Io batteries. Ca a Mastervolt battery charger remai coected throughout the witer? Yes, your Mastervolt battery charger ca easily be left coected i the witer. I fact, this is better for the batteries, Is havig 10% of my battery capacity as charge capacity sufficiet? Defiitely ot. You ca assume 25% ad up to as much as 50% with Mastervolt batteries. The old 10% rule was commo i the days whe battery chargers had o curret ad voltage regulatio, ad too high a curret could overcharge the batteries. Mastervolt battery chargers have perfect curret/ voltage regulatio ad are also equipped with a temperature sesor that esures the voltage is regulated accordig to the battery s temperature. Several loads are coected durig chargig the batteries ad these loads are also powered by the charger so the available charge curret for the batteries will be reduced. as they will the remai i optimum coditio ad there is o eed to take them home for rechargig. The 3-step+ chargig method esures a mothly absorptio cycle so the battery stays active. I sometimes have a limited grid coectio. Ca I still use a large battery charger? Yes. All Mastervolt battery chargers ad Combis are fitted with the latest electroics, reducig their power cosumptio by about 40% compared to covetioal battery chargers. For example, the power itake of Mastervolt 12 Volt battery chargers is summarised below for 230 V models. For 120 V versios, multiply by 2. The levels of curret specified are relevat to maximum capacity operatio, i.e. measured at the momet the battery charger supplies its full capacity. ChargeMaster 12/10 ChargeMaster 12/15 ChargeMaster 12/25 ChargeMaster 12/35 ChargeMaster 12/50 ChargeMaster 12/70 ChargeMaster 12/100 I additio, each battery charger with a charge curret higher tha 15 A (12 V) ca be equipped with a remote cotrol pael. This allows output curret to be reduced, causig the battery charger to draw eve less power ad prevetig the power fuse from blowig. 0.9 amps 1.2 amps 1.9 amps 2.5 amps 3.8 amps 5.2 amps 7.4 amps 160
BATTERY CHARGERS Ca I istall my battery charger i the egie room or compartmet? Yes. All Mastervolt battery chargers ca easily be istalled i the egie room as higher temperatures do ot egatively affect their curret output. The output curret will be automatically reduced if the ambiet temperature becomes very high, esurig that the battery charger will ot be damaged. Ca I charge batteries separately? Most Mastervolt battery chargers have a additioal output for a starter battery. This output supplies for example the starter battery with a maiteace charge. A umber of models are eve fitted with three outputs, allowig three battery sets to be charged idepedetly of each other. It is also possible to charge multiple battery sets via a battery isolator (also kow as a diode splitter). The voltage loss that occurs i the battery isolator wil be compesated by adjustig the charger (jumper or DIP switch settigs) or coectig positive ad egative voltage sese wires o the Mass series. Ca the battery charger be coected to the same battery isolator as the alterator? Although this is possible, it is better ad more coveiet to fit two separate battery isolators. If this should be problematic, use the battery isolator for both. I this case, make sure that the battery isolator or Battery Mate is powerful eough to simultaeously hadle both the battery charger ad alterator curret. What should the cable diameter be betwee the battery charger ad the battery? Whe calculatig the required diameter of these cables follow this rule of thumb: 1 mm² of cable thickess for every 3 amps. A battery charger of 50 amps, for istace, calls for a cable of 50:3 or 16.6 mm². The stadard cable closest to this is 16 mm². This applies whe the distace is three metres at most. For loger distaces you will either require a thicker cable or eed to coect a voltage sese cable (Mass chargers oly). What is the maximum distace allowed betwee the battery charger ad the batteries? I geeral, three metres is the maximum legth whe you are usig the calculatio method described earlier. A cable legth of 6 metres is also possible, but thicker cables must the be used. I the example used above, it is tha best to use 25 mm² cables. Example: Take a empty 200 Ah battery, a 50 amps battery charger ad a coected load cosumig 10 amps. Chargig time i this case would be aroud 200/(50-10) = 5 h, or 9 h i total icludig four hours of absorptio time. If the batteries are oly half-discharged, the recharge time would be 100/(50-10) = 2.5 + 4 h, 6.5 h i total. The absorptio time is shorter with gel ad AGM batteries at aroud two to three hours. These types of battery will therefore recharge faster tha covetioal oes (see also Chargig batteries ). How log will it take before my batteries are fully recharged? The chargig time of a battery is directly related to the ratio of battery to charger capacity. Other importat factors that decide how log it takes for a empty battery to completely recharge are the battery type ad the power cosumptio of the potetial cosumers. As a rule, divide the battery capacity by the maximum charge capacity ad add four hours. The four hours are for the absorptio time, durig which the battery determies how much more curret is ecessary for it to retur to its fully charged state. Of course, this rule does ot cosider the power cosumptio of other coected equipmet: If loads such as a refrigerator or lights are coected, their power cosumptio eeds to be subtracted from the available charge capacity. 161
What is voltage sese? No matter how thick, every cable has some resistace, resultig i a certai amout of voltage beig lost betwee the battery charger ad the batteries. This voltage loss depeds o the thickess of the cable ad the battery charger curret. A battery charger measures as stadard the voltage at its output termials. This voltage is higher tha the battery voltage. The output voltage of the battery charger mius the voltage loss across the cables is the battery voltage. Whe a lot of voltage is lost o the cables, the battery charger might switch to the absorptio phase too early, which meas that the battery will ot become fully charged or chargig time will icrease. To compesate for voltage loss via the cables, sese wires have to be coected betwee the battery charger ad the batteries. These thi wires esure that the charger measures the voltage directly at the positive ad egative poles of the battery rather tha o its output termials. The voltage lost durig chargig is compesated ad the batteries are charged quickly ad effectively. The voltage drop over, for example, a diode splitter ca also be compesated i this way. What is 3-step+ chargig techology? Mastervolt s 3-step+ chargig techology is the fastest ad safest way to charge gel, AGM ad ope wet type batteries. It cosists of the followig phases: First step: BULK phase I the first step, the bulk phase, the battery charger delivers its maximum curret (e.g. 50 amps for a ChargeMaster 12/50) ad battery voltage icreases. The duratio of this phase depeds o the battery capacity, charger capacity ad ay cosumers coected to the battery durig chargig. The bigger the battery, the loger this step takes; the larger the charger, the shorter the stage. If cosumers such as a refrigerator is coected, it will also eed to be powered by the charger, reducig the charge curret goig ito the batteries ad icreasig the time ecessary for chargig. Secod step: ABSORPTION phase The secod step, the absorptio phase, begis oce the battery has reached its maximum voltage. At this poit the battery is aroud 80% full, ad the charge curret begis to slowly decrease. At 25 C, the maximum voltage is 14.25 Volts for a 12 V battery ad 28.5 Volts for a 24 V oe. The absorptio phase lasts three to four hours o average, depedig o the battery type, battery charger, ad the extet to which the battery was charged at the begiig. Durig this stage the battery will be charged to 100%. Third step: FLOAT phase Oce the battery is fully charged at the ed of the absorptio phase, the float phase begis. The Mastervolt battery charger switches over to a maiteace voltage so that the battery remais fully charged ad i optimum coditio. Ay existig cosumer loads are also powered. The charger remais i the float phase util the battery voltage falls due to a major load, or the battery charger is uplugged because the power coectio was removed. What is a temperature sesor for? It is vital that you use the right charge voltage to charge a battery. The correct charge voltage is ot always the same however: Cold batteries eed a slightly higher voltage to fully charge ad, coversely, warmer batteries require a lower charge voltage to avoid overchargig. Mastervolt battery chargers are pre-set to a battery temperature of 25 C. Whe the temperature sesor is coected to the charger, the output voltage will vary by 0.03 V per C (for a 12 Volt system) ad 0.06 V per C (for a 24 Volt system). This is i accordace with the advice of most battery maufacturers. At a temperature of 15 C, for istace, the maximum charge voltage for a 12 Volt system is 14.55 Volt, ad at 30 C it is 14.1 Volt (the correspodig values for a 24 Volt system are 29.1 ad 28.2 Volt). Voltage is o loger icreased oce temperatures drop below 12 C, esurig that the oboard system is protected agaist excessive voltage. Coversely, the charge voltage is reduced to 12 or 24 Volt above 55 C i order to protect the battery agaist overchargig at this extremely high temperature. The coectio of a temperature sesor esures that the battery is quickly ad safely charged with the right voltage. 162
BATTERY CHARGERS PLUS phase Most Mastervolt battery chargers are equipped with a extra step, the PLUS phase. Durig periods whe the battery is restig, a absorptio cycle lastig oe hour will take place every 12 days to esure that the battery stays i perfect coditio. This icreases the lifetime of your batteries. Retur Amps Durig the absorptio phase, the battery accepts progressively less curret. Oce the charge curret remais uder a certai level for a give period of time, the battery is cosidered to be fully charged. This maximum charge curret is called the Retur Amps, ad the correspodig period the Retur Amps Time. The battery charger takes this as a sigal to switch over to the ext step, the float phase. Just like may other parameters of the battery charger, Retur Amps ad Retur Amps Time ca be set by the istaller with the help of software that is freely available o the Mastervolt website. I fact, the istaller ca use this software to customise the battery charger to your oboard system requiremets. Ca I charge differet types of Lithium Io batteries? Yes, that is o problem with a Mastervolt battery charger because the desired charge characteristic ca be set. Ca multiple battery chargers be parallel coected? I additio to simply beig chargers, Mastervolt battery chargers also provide power for the 12 or 24 Volt oboard system. They ca easily be parallel coected should you wish to icrease capacity. I fact, this is ofte the oly way to power your 12 or 24 Volt system with the 230 or 400 Volt power coectio. Similarly, should you eed a charge curret higher tha 100 amps for a 24 V system or 80 amps for a 12 V system, several battery chargers ca be parallel coected. A parallel system with multiple battery chargers does ot require ay special equipmet. It ca be istalled i exactly the same way as a sigle charger, except that each charger will have its ow cables leadig to the battery or the DC distributio. Wirig for the voltage compesatio is also coected separately for each charger: Remember to make sure that the sese wires used to compesate for voltage loss over the cables are coected before the mai fuse ad o the system side. This will prevet the output voltage of the charger from becomig too high if a fuse is defective. The temperature sesor for each charger eeds to be separately coected to the battery, that you expect to reach the highest temperature. If the chargers ad sesors are properly liked, the charge curret will be evely distributed over the coected chargers. 163
The possibility remais that oe of the chargers will switch to the absorptio phase sooer tha the others. This is a perfectly ormal pheomeo caused by toleraces i the adjustmet, with o effect o charge time ad charger operatio. Whe parallel coectig multiple battery chargers, we recommed that they be of the same model, type ad charge capacity. For istace, whe a 100 amps charger is liked parallel to a 50 amps charger, the charge curret will ot be evely distributed over both. Although this will ot affect the chargig process or be detrimetal for the chargers, it is more efficiet to istall two chargers of 75 amps each. Mass battery chargers are also capable of sychroisig the chargig process. Ca I parallel coect a battery charger to the alterator? It is possible to parallel coect a battery charger with, for istace, the alterator of the propulsio egie. This situatio occurs if the 230 V geerator is also started up while the egie is ruig, ad is ot a problem i itself. How ca I charge batteries with limited power? The available power coectio is ofte too weak whe multiple battery chargers are fitted i parallel. I order to prevet the power coectio from beig overloaded, it is best to oly coect oe of the battery chargers. Although this will icrease the time eeded for chargig, you are ormally coected to the grid for a loger period of time (overight) ayway. Both battery chargers ca be powered if the geerator is ruig, as the geerator usually delivers more output tha a power coectio. The two battery chargers will ot cause the power coectio to be overloaded. 164