Electric Fiero Lithium. David Malloy

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Frederick Manning
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1 Electric Fiero Lithium David Malloy

2 The Story Thus Far Started Conversion of a Pontiac Fiero mid 2007 Advanced DC 9, Curtis 144V controller Maiden voyage 12/2008 Used Lead Acid Batteries (12*Trojan 30XHS) Lithium was still expensive; anxious to get started Range was 18 miles, handling was heavy Batteries were the weak link, but there were many areas for improvement Presented to the NBEAA Oct Daily driver throughout 2009 And then, after 13 months and 2000 miles

3 Range started dropping Battery Failure! Range went down to 15 miles or so Tracked it down to a failing cell under load All cells showed the same voltage at rest But under load, one cell sagged more than others And the self discharge rate was much higher Lithium prices were dropping and decided to upgrade and so began Phase II

4 Outline Batteries Battery Management and Instrumentation Other Upgrades Charger Control Board Vacuum Pump Heater Lessons Learned Scorecard Future Projects

5 Batteries

Battery Choice ThunderSky (now Sinopoly) 160Ah Thunder Sky 160Ah Readily available Installed in blocks of four Size comparison: Lithium(x4) = 4 x 10.2 x 11 Lead Acid(x1) = 6.75 x 14 x 10.

6 Battery Choice ThunderSky (now Sinopoly) 160Ah Thunder Sky 160Ah Readily available Installed in blocks of four Size comparison: Lithium(x4) = 4 x 10.2 x 11 Lead Acid(x1) = 6.75 x 14 x 10.1 Decided on a 44 Cell Pack Have 11 blocks of four cells 4x Lithiums have a slightly higher nominal voltage than 1x SLA Wanted to be conservative on max voltage In retrospect, 48 cells would have been fine and would have given more range

7 Lead Acid Battery Boxes Original design was bolted steel Cheap, within my abilities, but far from ideal

8 Lithium Battery Boxes The upgraded design: TIG Welded Aluminium Bought a welder, learnt from youtube and trial and error Weight savings total: ~120 lbs

9 Lead Acid Battery Layout 12 Trojan 30XHS Lead Acid Cells 7 rear, 5 front (58%/42%)

10 Lithium Battery Layout 44 ThunderSky 160Ah Lithium Cells 28 rear, 16 front (64%/36%)

11 Battery Safety Layout Notes Layout: lowest voltage cell at rear left, highest voltage cell at front right. Two contactors, one fuse, one circuit breaker in high current path For Lithium, removed the Anderson connectors and added the circuit breaker Battery Box Construction Lithium cells came in packs of four. Retained original holding plates and straps when possible Cell straps and BMS connections covered with plexiglass (gives protection from a dropped wrench ) Lugs feed through plexiglass, connected via jumpers

12 Battery Box Construction

13 Lithium vs Lead Acid Lead Acid Lithium Pack 12 * Trojan 30XHS 44 * ThunderSky 160Ah Cell Dimensions (w*l*h) Cell Volume Pack Volume Cell Weight Pack Weight Expected lifetime (# charges) Capacity rated Capacity usable(est) Capacity pack(est) 6.75 x 14 x cu in cu in 66 lbs 792 lbs 2.55 x 4 x cu in (224.4) 4937 cu in 12.3 lbs 542 lbs ( 250lbs) 1/2 (X.43) 2/3 (X.68) X6 72Ah (75A for 57 min) 44Ah (est) 6.4KwH (11.8V *12*45Ah) Maintenance Monthly Watering n/a 160Ah (480A for 20 min) 106Ah (est) 15KwH (3.2 * 44 * 106 Ah) X2.3 Cost $2,200 $10,000 X4.5 Range went from 18 to 40+ miles

14 Battery Management and Instrumentation

15 Battery Management Functions While driving 1. Measure pack state of charge 2. Measure individual cell undervoltage 3. Indicators (/ preventative actions) if pack or cell is undercharged Idiot light, buzzer, limp home mode While charging 4. Stop Charger when the Pack is fully charged 5. Stop Charger if a single cell gets overcharged and 6. Cell Balancing (keeping cells in balance) 7. Diagnostics (early detection of a failing cell)

16 Lead Acid Battery Instrumentation State of Charge DC/DC Converter Status Pack Charge Status Ammeter Motor OverTemp PakTrakr

17 Lithium BMS Requirements BMS Feature Lead Acid Lithium Pack SOC YES Curtis REQUIRED Cell UV YES PakTrakr REQUIRED Idiot Light Buzzer Limp Home Charge Termination Cell Overvoltage No No No Algorithm No. (results in Hydrogen Gas) REQUIRED Nice to have Maybe REQUIRED REQUIRED Cell Balancing n/a A strategy is required. Automatic balancing is a nice to have (?) Diagnostic Basic logging supported but not used Astrategy is required. Manual voltmeter is the fallback. BMS Requirements for Lead Acid vs Lithium are slightly different.

18 Lithium Instrumentation Pull to Trip Circuit Breaker E Xpert Pro Voltmeters For Pack and 12V

19 E Xpert Pro Single most important gauge Pack gas gauge, voltmeter and ammeter Measures: charge and discharge current, consumed amp hours Used with 5:1 prescaler Keeps high voltage out of cabin Programmable

20 Lithium BMS MiniBMS

21 Mini BMS Analog BMS with all the basic features While driving If any cell drops below 2.6v (the Low Voltage Cutoff), the BMS sounds a buzzer and turns on a dash light While charging If any cell goes over 3.8v (the High Voltage Cutoff), the BMS stops the charger Also supports Top balancing If the cell goes over 3.7v (the Shunt Voltage Threshold ), the shunt resistor is enabled (current is ~750ma) The benefits of Top Balancing are controversial And supports Limp home mode The BMS Master can control the accelerator potbox But this was not used

22 Mini BMS Installed Grouped the remotes rather than place them directly above a cell Easier to see the state of the pack Spaghetti wiring Mixed feelings about the results

23 Other Upgrades

24 Charger Wanted a 110V opportunity charger Had a 220V onboard charger 220v plugs weren t standardized; always charged at home Removed the Zivan NG3, added an ElCon PFC 1500 Supports both 110 / 220 Has BMS integration with charge enable contacts Rethinking the Strategy J1772 is now standardized; an EVSE upgrade in progress Will also add a larger charger onboard

25 Control Board Contactor Control Primary Contactor, Secondary Contactor, and KSI relay Lockouts: Inertia Switch deactivates contactors on collision High Pedal accelerator must be off to enable contactors Charger cannot enable contactors when charging Recommended operation: Primary ON when charging or enabled (turns on DC/DC) Secondary ON when enabled KSI ON when accelerator depressed Charger Control Integrate the BMS with the Charger Instrumentation Drive Dash Indicators, etc

26 Control Board Lead Acid Lithium v1

au Pacific EV EVCM (EV Control Module) www.

27 Contactor Control Off the shelf Evworks ZEVA EV management system Pacific EV EVCM (EV Control Module)

28 Control Board In Progress Battery / Ignition / Ground Inertia Switch Primary Contactor Potbox Microswitch Secondary Contactor, KSI BMS Master

relatively quiet High current draw (~20A) Not

29 Vacuum Pump Gast original conversion Relatively noisy Not integrated Tried the VBS Works quickly; relatively quiet High current draw (~20A) Not integrated Settled on MES DEA Well integrated Quiet and low current draw

30 Heater Had wired up a single element of a ceramic heater Did not work well Considered alternatives Electric fluid heater Propane, natural gas heaters, truck cabin heaters Finally Wired up both elements of existing ceramic heater Works well and quickly; fine for defrosting windows Single on off switch so no automatic temperature control Conclusion Ceramic is OK but need to consider temperature control Should have a lockout so element is not on unless fan is on Current draw (~8A) is acceptable

31 Lessons Learned Cell Failure and Cell Diagnosis 2/44 Lithium cells replaced in pack so far Contactor Control Failure Contactor would drop out when driving. Probably due to contact pitting in one of the relays DC/DC Converter and 12v Accessory Battery Original conversion downsized the 12v battery. The TBS vacuum pump strained the 12v system and caused battery failure. Best way to measure is with a 12v analog meter Coupler Failure Original clutchless conversion was misaligned and destroyed itself after 3500mi. Was redone.

32 Coupler Failure!

33 Scorecard

34 Lead Acid Component Scorecard Component Now Major Dislikes Batteries Trojan 30XHS SLA Capacity, weight, weight distribution, safety Battery Boxes Bolted Weight, durability Drive System ADC 9 / Curtis 1231C Whistle when starting; No regeneration No Integrated contactor control Adapter Design Clutchless Pack Charger Zivan NG3 Onboard 220V No 110V, not sealed, no BMS integration DC/DC Converter Zivan NG1 Not sealed Heater Ceramic Not functional Vacuum Pump Gast/vacuum switch/reservior Noisy, not integrated Contactors Albright Noisy, not sealed Instrumentation PakTrakr, LEDs, ammeter High voltage in cabin, no data logging Safety 2 contactors + fuse No Emergency Disconnect

35 Lithium Component Scorecard Component Now Improvement areas Batteries 44*160Ah ThunderSky A few more cells (8) would give more range and performance Battery Boxes TIG welded aluminum Aluminum is fine, still thinking about overall mechanical design. Drive System ADC 9 / Curtis 1231C Whistle when starting; No regeneration No Integrated contactor control Adapter Design Clutchless Pack Charger Elcon 1Kw Has BMS integration; need a bigger model DC/DC Converter Zivan NG1 Not sealed Heater Ceramic Works now, but only one setting Vacuum Pump MES DEA Better than Gast pump, but still too noisy Contactors Albright Noisy, not sealed Instrumentation expertpro, MiniBMS, LEDs Logging BMS in development Safety 2 contactors, fuse, circuit breaker

36 Currently In Progress Control Board Upgrade J1772 Logging BMS DC/DC Converter Upgrade Planning for Next Conversion 1984 Pininfarina Spider

37 J1772 EVSE Purchased EVLink / Schneider Electric from stock at Home Depot in Rohnert Park Installation requires 30 50A 220VAC 18 cable was too short. Added a 12 extension using a Bulgin Buccaneer 900 plug/socket (IP68, 32A, 600V)

38 J1772 Inlet and Active Vehicle Control

39 Malloy BMS In Progress Digital Monitoring CAN bus Real Time display Logging

40 Summary All upgrades have contributed to a safer, more reliable, and more pleasant to drive car The upgrade to Lithium Batteries has made the single biggest difference

USER MANUAL MINI BMS DISTRIBUTED VERSION

USER MANUAL MINI BMS DISTRIBUTED VERSION MiniBMS is a battery management system designed for LiFePo4 cells, used in Electric Vehicles. MiniBMS is designed to be reliable and cost effective solution; it