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Chevy Volt battery module Gen 1 in parallel

3736 Views 5 Replies 4 Participants Last post by  tomrock, 
Yabert
Hi
Last year, I've done a ghetto PCB with resistor to put three 12 cells module in parallel: http://www.diyelectriccar.com/forum...-volt-battery-module-parallel-45v-178681.html

Since this time, I've learned to design PCB and I designed a plug and play solution to reuse the Chevy Volt connectors (pic). My goal is to use one Zeva BMS with two (or more) 12 cells module to create 45V battery of 90Ah, 180ah, or more Ah.
In my head (mechanically mind) it was easy, but I probably do something wrong because the result are not those expected.

I've start with two modules. On first, all the cells was at 3.96V and all the cells was at 3.80V on the second.
I plug my PCB with orange connnector (circle on pic) with 26 one ohm resistors and let it balance the modules. It was not plug to the BMS.
24h after, all the cells was equalized at around 3.88V exept the most negative and the most positive one.
During the balancing, the black AWG 8 wires and the multimeter on the picture was unplug.
I add the pics is the schematic and my PCB if that can help.

Is there I miss something?

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Yabert
Seem like I've not correctly done my first test.
I tried another test with all wires connect as you can see in picture.
One module was at 3.97V and the other at 4.04V. 10h later, all the cells was at 4.01V. Perfect!
Seem like my 48V 90Ah batterie with a single BMS is fine.

If someone need PCB to put two Volt modules in parallel, PM me.

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Yabert
Yabert said:
One module was at 3.97V and the other at 4.04V. 10h later, all the cells was at 4.01V. Perfect!
Click to expand...
That was true before I replug the BMS.
The Zeva BMS seem to have some resitor at the input to energized itself and this caused around 0.1V of imbalance on the first cell when everything is plug.
Solution: I removed all the 1 ohm resistors and I replace it by jumpers (0 ohm resistors).

The cells wires are now unprotect in case of imbalance of parallel cells, but it will be fine for my application (<1C discharge, <0.1C charge, LV 3.5V, HV 4.1V).

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