Wednesday, July 16, 2008

First attempt at charging

Tonight the epoxy on the console repair was ready to I mounted the console and switch panel back into the vehicle. At that point, everything was ready to power up for the first time. I was not sure what to expect as the batteries are 10 year old (Ni-Cad) and have been setting fully discharged for a long time. I plugged it into the wall and lights blinked, the fans came on, and generally it seems to power up. It put some error message in german on the screen and looped on displaying 4 different screens over about 3 minutes. Once I dug out the user manual, I figured out how to get it to speak English. It is complaining the BMS's need new firmware downloaded (yup, batteries were dead) and it was waiting for the 12V to stabilize. I let it run in this mode for a while to see if it would put any energy into the batteries in this state. The BMS in each battery runs of just the batteries so they have to have some charge to bring up the BMS. Meanwhile, I looked through all the settings I can reach easily and found it has only 58 miles on it. I guess that means not too many parts are worn out (except the abused batteries). After an hour of charge, I pulled the 120v plug and low and behold, it kept running for a while. After another 2 hours on the charger, I measured the voltage of both batteries with a meter. With 280 C sized Ni-Cad cells in series, the voltage is supposed to stay between 280 and 410. Battery 1 showed a voltage of only 90 volts. Battery 2 showed a more healthy 289 volts. I have two other batteries (one without BMS that I can take cells from) that with some luck will let me come up with 2 working packs. This would let me debug the rs485 BMS protocol so I can emulate it if I need to (if I go with Lithium). It also would let me try out the motor and all the electrical devices and see if they work. Not sure why it still thinks the 12v is not stable but may be because of the 90v battery. I'm going to try to build a set of cable extenders for the batteries so I can debug them outside the vehicle (much safer and easier). Please be careful if you are dealing with high voltages such as this. I bought some 500v lineman's gloves so I won't get hit with a fatal voltage if I get across the battery voltage while working on it. I'm off to look up Molex connect numbers.

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