New GEVCU module for Orion BMS
Michael Neuweiler
Hi folks,
I had some problems with my battery pack after a long down-hill ride with regen on an almost full pack: some strange odors.. later a large voltage drop (50V) while accelerating and when I removed the cells, in one box had this smell of ripe pears (vented cells). After testing more than 60 cells (of 119) I found one with 0.00V and the rest with a capacity between 96 and 102 Ah. (after more than 10'000km). So they seem to be ok. I'll test the remaining cells in the coming month.
Out of the following reasons I decided to switch my philosophy from bottom balancing without monitoring and bought an Orion BMS for 144 cells:
- My car had a bad cell which almost remained undetected (the
car was driving and charging fine) - if I didn't keep a keen eye
on all the params in the dashboard, I'm pretty sure, the car
would have burned itself and its surroundings to the ground
while charging.
- About 45 cells are very hard to access (>1 day work to dismantle) and if something goes wrong I want to know which cells are affected and not take apart the car and test every single cell over a period of 2-3 months.
- I want to be able to monitor the cells with load on them (100A or more). As I don't have expensive testing equipment it has to be done while driving.
- Before damaging any cells regen or a charger has to be throttled down. Before the voltage was limited for regen with a safety margin (420V for 119 cells) but it still hurt the cells. I guess that once the first cells are full but the pack voltage is still below the limit, regen still pumped 80-100A into the already full cells. This is probably what killed them (or hopefully only one).
I don't want to start a debate about which religion/philosophy is
better and safer. I'm not keen on attaching 119 wires to the
batteries - many things can go wrong there and cause a fire. I
expect the fire hazard to be higher during charge without a BMS
because of undetected bad cells, but higher during operation with
a BMS due to lose wires or a short. I'd rather have the car go up
in flames on a street or highway than in a garage under a building
with people in it. So I made my decision. I just wanted to let you
guys know that I'll develop a GEVCU module for the Orion BMS and
let it influence the charger and motor controller via GEVCU. As
always, I'll keep it in my repo
(https://github.com/neuweiler/GEVCU ) and ask Collin to merge it
into his ArduinoDue branch.
Cheers,
Michael
-- -- What we do in life, echoes in eternity (Maximus Decimus Meridius)
Hanno Hinrichsen
Im using the Orion BMS in my 911 electric and Im satified with it.
Please think on reguläre the current while regen. Thats more likely the reason for destroying cells. Is the broken one in a cold area of the Pack?
