[DreamMachine]

Hello all,

Planning on putting 20 leaf cells (in series using the stock connections) in a battery box in the back of my car, and another 20 cells in the front engine bay. I was planning on paralleling the two packs with bus bars in the main wiring box of the car, but I recently watched Jehu's video where he had a wire in a small parallel bundle completely burn as it was the shortest, and took the majority of the current (least resistance). I'm just wondering if this would affect my pack, as it would draw more from the front pack and negate the bottom balancing of the pack.

Cheers!

 

[DreamMachine]

I think it's worth doing the corner connection thing, just so that the front pack doesn't do most of the heavy discharge work (assuming front wheel drive), with the back pack lazily charging the front pack and taking only a modest share of the motor load. The front pack would wear out faster than the back in that situation.

Sorry Coulomb, I don't quite understand what you mean. If I were to take the positive connection the front pack and the negative connection or the rear pack to the motor controller, I would have a series connection which would give me 366V rather than the 168 max that my controller can handle. I do however understand the idea behind the natural balancing over time at rest, but while driving I was unsure about the balance in capacity of the front/back over time as I am not planning on running a BMS.

But copper parallels very well due to its positive resistivity coefficient. Lenght tolerance isn't normally a factor for wires and bars.

My opinions.

Thanks major! I was never taught about increased resistance with heat, so that never crossed my mind. As for why Jehu would possible use a shorter cable on one side, not too sure: possibly going around a very tight bend?

I only ask as there is going to be about 9 feet of cable connecting the rear batteries to the front bus bar, so I figured at that length the resistance would play a bit more of an effect then a couple of inches difference.

 

[DreamMachine]

As long as your cable is properly sized and quality. If you're going to lose sleep over it just use a gauge size or two larger.

Regards,

major

I plan on using 1/0 for each pack, and then connecting the two with a 2/0 cable go to the controller. Probably overkill, but I figure it's better safe than sorry.