Yes, your numbers / thinking are good here. For wiring, 2AWG (33.6 mm2, chassis a = 181, transmission a = 94) would likely be adequate for short runs. Some like to go thicker - as in 1/0AWG (53.5mm2, chassis a = 245, transmission a = 150). I use this chart for my decisions - https://www.powerstream.com/Wire_Size.htm Chassis a (very short runs) can handle a LOT more than Transmission a (longer runs - say 10, 20ft+)
Thank you for this tip. I watched D. Poz compress these cells in a video where he makes a module from individual cells, but I had no idea why. I still have one original module that I've not touched, and will measure torque on the bolts before disassembling so when I re-torque the newly-configured modules, I'll at least be in position to avoid this problem. If anyone's interested, I can post the torque specs that I find here. Just let me know. Do you know if the problem was due to not compressing at all, or compressing, but just not enough . . . ?
Thanks much for this feedback and for the wire-gauge link. I will take your example and use red and black colouring for the shrink wrap on the bus bars. Maybe I'll also print up and post your #1 rule inside the cabinet, once I've got that sorted. I'm constantly aware that I could be doing something that will destroy my equipment and/or worse, so esp. given that I am admittedly a newbie, any safety /damage-prevention advice also much appreciated.Yes, your numbers / thinking are good here. For wiring, 2AWG (33.6 mm2, chassis a = 181, transmission a = 94) would likely be adequate for short runs. Some like to go thicker - as in 1/0AWG (53.5mm2, chassis a = 245, transmission a = 150). I use this chart for my decisions - https://www.powerstream.com/Wire_Size.htm Chassis a (very short runs) can handle a LOT more than Transmission a (longer runs - say 10, 20ft+)
Excellent pic/wiring-diagram - really help discussion and gives you something to check off when doing wiring!
> I could leave the existing series connections intact.
Yes I agree. Once you're in a position to put a load on the battery (or part of it) you can just pull the amps and touch the existing connections to see if they are warm/hot. As long as they stay warm->cool under max load, then that's all you need in my opinion.
>wondering if I can then use vertical bus bars to connect each of the cell groups - so bus bars for the red lines in my diagram
Sure - whatever works with hookup/easy-maintenance for the physical battery. For my inter-pack connections, I buy smaller copper pipe and flatten it, cut it into bars, and drill holes to use bolts to hook packs together. You just need the overall mm-squared (n the chart above) to carry the amps you need.
>wrap the bus bars in heat shrink tubing for safety
Again, great! Some use shrink-wrap. I use electrical tape - have gone thru 10-20 roles of it over 3 years. I really like to make sure + = RED and - = BLACK. So I'll wrap black wires 100% to make them RED if they are positives. In this way, the #1 rule - don't touch RED and BLACK except when hooking in series + to -
>would I be able to leave the existing copper busses that connect each 3-cell group to the next and use the existing module terminals, just connecting them via the appropriate gauge to a common bus bar
Again, sure. Me personally - I'm good with non-uniformity to leverage what's there as long as the connections are sound and maintainable.
For the hookup, this is what I'm picturing from the conversation... and if this is correct, then yes sir, you're right in the zone. It sounds like you have a firm handle on things, a good diagram for hookup, and thinking about things very well...
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No I don’t know how much they were compressed, but they cells-packs I seen expand did not have any compression
OK, thanks. I'll post torque spec after I have the chance to measure it from my one untouched pack - for anyone with the same module.
That fuse was on a Chevy Volt. I don’t think the Chevy Bolt comes with a fuse for each cell on the battery
Excellent! Sounds like an ideal pack. In terms of permitting, I'm also planning to pull a permit, but have no idea what kind of regulation my inspector will be following to check the battery. All he told me is that all components have to be certified, but I'm not sure what that means when it comes to the battery, and don't want to push it. I'm not sure, for example, what he'll say about a BMS. What's your situation for permitting on the battery part of your system?
Yes, good point. I'm not sure either, but there are white globs of some type of rubber insulator on the board. I'll pull them off when I get a chance and take a closer look. Here's another pic.
OK, thanks. I'll find this out. For framing inspections, my AHJ tends to use older codes rather than newer, but it seems important that I get clear on the version of the electrical code and then get everthing installed and inspected before they upgrade
. Appreciate the tip.
