Project Precedent

[Pat911]

@Walter, yes, you’re right, I forgot to mention that. I had that problem too.

UncleJerm, that would work but it would take an awfully long time. Best to get a 16s active balancer and just switch it on when required. An active balancer doesn’t waste energy either, it shifts power from high cells into low cells. But don’t leave it turned on, it can put your cells out of balance if switched on when the cells are at a mid state of charge.

https://www.amazon.com/Capacitor-Equ...s%2C283&sr=8-3

[UncleJerm76]

Thanks for the link Pat, I saved it.

It’s going to be a while longer before my top balance is done. I started at way to low of SOC. I don’t know why the CV dropped to 3.63v recently but I’m afraid to touch it until it’s done.



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[WalterM6]

Still need to sort out a few items before it’s ready to ride. Like how I’m going to secure these lithium packs to the cart, protect the top terminals from accidental shorts and finding an eye-pleasing solution for the BMS balance wires.

Here's a few ideas. I copied them from a fellow forum member called "Aussie in Seattle".

The battery compartment cover was made out of an old windshield, but you could use plexiglass from Lowes

I used Diamond Plate to reenforce the floor and to raise the floor to run the wires underneath.

I used cutting boards from amazon for the end caps and 5/16 threaded rod for the compression bolts.

Of course, you would have to make two of these.

[UncleJerm76]

Originally Posted by WalterM6

Here's a few ideas. I copied them from a fellow forum member called "Aussie in Seattle".

The battery compartment cover was made out of an old windshield, but you could use plexiglass from Lowes

I used Diamond Plate to reinforce the floor and to raise the floor to run the wires underneath.

I used cutting boards from amazon for the end caps and 5/16 threaded rod for the compression bolts.

Of course, you would have to make two of these.

Those pics are giving me some great ideas — I really like the plexiglass top. That would protect from accidental shorts while still allowing visual inspection. I don't need to compress, but Ive got some other ideas that are churning in my head that should work in its place and these pics help fill some gaps I had with my ideas. Thanks Walter!

[UncleJerm76]

BTW, I really appreciate the support and ideas from you guys!

[UncleJerm76]

Waiting on my pack to finish top-balancing before I can do to much more so I curiously measured individual voltages last night just to see how they were doing. I starting measuring from the cells hooked up to the power supply clamps (far right) and for every cell that I got further away from the clamps the voltage dropped 9mV. Has anyone else experienced this when doing their top balancing?




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[Volt_Ampere]

No. There is no reason why they would not all read the same - but are you moving your meter negative AND positive to each battery? There may still be some current flowing. Looks like you have all of the cells wired in parallel - they should top balance quickly that way.

[WalterM6]

I don't know for sure but I've been told that when balancing you should connect your power supply to both end of the pack. You have both + and - connected to the same end of the pack. Notice how it is connected in the picture.

[Pat911]

9mv per cell is almost 150mv from the highest to the lowest. That’s too much. It seems like you’re using quite thin cable, hence the voltage drop when current is flowing.

[Volt_Ampere]

It should all settle out fairly quickly though.