Parallel'ing balance leads???

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milesinfront
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Parallel'ing balance leads???

Post by milesinfront » Jan 24, 2018 12:54 am

Hi forum,

I have just connected two packs in parallel.

Each pack consists of 5s+3s+5s, 8000mah Zippy lipos. (13S2P)

Should I connect the balance wires in parallel too?

Cheers in advance.

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jonescg
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Re: Parallel'ing balance leads???

Post by jonescg » Jan 24, 2018 1:05 am

So you have two of each Zippy packs?

As long as cell 1+ of the first 5s pack is in parallel with cell 1+ of the other pack, you're on the right track.

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milesinfront
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Re: Parallel'ing balance leads???

Post by milesinfront » Jan 24, 2018 1:09 am

That's the plan...

Just a little worried about them carrying too much current. Under normal circumstances I'm sure they'd be fine, but if one of the high current wires/connectors failed they could easily become fuses! LOL

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Re: Parallel'ing balance leads???

Post by amberwolf » Jan 24, 2018 2:35 am

Assuming the wiring for the whole pack is well-built, if one of the high current wires fails, something so catastrophic has gone wrong that the balance wires being fuses might be the least of your worries. ;)

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milesinfront
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Re: Parallel'ing balance leads???

Post by milesinfront » Jan 24, 2018 2:38 am

Indeed... LOL

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dogman dan
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Re: Parallel'ing balance leads???

Post by dogman dan » Jan 24, 2018 7:37 am

That would be a good thing then in that case, for them to act like fuses. Tape up your parallel connections, if not permanent, so one cannot get unplugged. I killed a pack letting that happen once.

But personally, I gave up using the balance wire parallel harnesses I built. For starters, there is enough wire already in a bigger pack, like 6 or 8 packs for 500 wh.

Secondly, my experience has been that they did not really need connecting, unless you are connecting to a balancing charger. The way I use my batteries, I tend to only need to balance about once every 3 months. They stay balanced.

So what if one pack has a weak cell, and needs to be supported by the other one, through the balance wire? If I have a cell that bad in there, I want to know which one, and get rid of that pack!!!!!

So you see, for me at least, no need at all to use that paralell harness on the balance wires, unless I'm doing a balancing charge on that pair of packs, on an RC charger. I just check each pack one by one with a cellog 8, and then can still charge just one low cell as needed with the RC charger, through the balance plug, at 2 amps or less.

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milesinfront
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Re: Parallel'ing balance leads???

Post by milesinfront » Jan 24, 2018 2:57 pm

Thanks for sharing your experience. I'll keep an eye on them and see how balanced they stay in the long run. At the very least my parallel balance connectors will be useful for maintenance charging.

Cheers! :)

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dogman dan
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Re: Parallel'ing balance leads???

Post by dogman dan » Jan 25, 2018 8:46 am

To clarify, the way I wire up packs these days, is series first. I run 14s, so it starts out with 6s, 6s, 2s, 5 ah. then another identical section is paralleled with an adapter that makes the y connection at the mains of each 14s section. Human bms, or call it a naked pack.

if you did a more permanent parallel first connection, like soldered or crimped, then you would cut and Y connect the balance wires too. Why?, because now you would actually have less balance wires and plugs cluttering up the battery compartment. Then you could attach a bms if you wished to.

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Re: Parallel'ing balance leads???

Post by milesinfront » Jan 25, 2018 5:05 pm

That's pretty much how I do it, but was planning to use parallel-charging balance leads to connect the sister cells of the two packs. It's pretty messy, but does the trick. :) The application is an old Rad2Go E36 scooter. It's running a C80-100 motor. HEAPS of power in a very sketchy and unstable platform. What's not to like??? LOL Just a fun ongoing experimental toy to make life a little more interesting.

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Re: Parallel'ing balance leads???

Post by wineboyrider » Jan 26, 2018 11:17 am

Hobby King sells parallel balance leads for different series batteries. I use a 6s, 4s, and 5s harness to balance charge multiple packs.
ES IS SAVED! THANK YOU JUSTIN.

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Re: Parallel'ing balance leads???

Post by dogman dan » Jan 27, 2018 8:35 am

To clarify, you do that when you want to balance only WB? That would make sense to me.

I just wanted less crap hanging off the packs when running them. If you do have tons of space in the battery box, then its not a problem to have a big ass bundle of wire there.

Much depends on the use pattern, mine is a big pack for occasional 2c discharge, but mostly the pack is so big its running on .75c. So balance is not a problem, literally balance them 4 times a year, and never found on very far out yet, in years. The current pack is a full 2 years old now. Still stays in balance.

When assembling a new lipo pack, I won't tolerate an individual pack that does not stay balanced initially, so no weak cells ever in my assembled pack. That means for me, balance wires are not needed whatsoever.

But if you need them, for sure, go ahead and hook them up. But if you do and discharge, it becomes even more crucial that you never have an accidental disconnect of the main wires. You could end up pulling 10 amps through that balance wire connector.

So if you do have them attached all the time, I'd strongly recommend a solid soldered or crimped permanent parallel connector at the main wires.

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Re: Parallel'ing balance leads???

Post by wineboyrider » Jan 27, 2018 12:07 pm

dogman dan wrote:
Jan 27, 2018 8:35 am
To clarify, you do that when you want to balance only WB? That would make sense to me.

I just wanted less crap hanging off the packs when running them. If you do have tons of space in the battery box, then its not a problem to have a big ass bundle of wire there.

Much depends on the use pattern, mine is a big pack for occasional 2c discharge, but mostly the pack is so big its running on .75c. So balance is not a problem, literally balance them 4 times a year, and never found on very far out yet, in years. The current pack is a full 2 years old now. Still stays in balance.

When assembling a new lipo pack, I won't tolerate an individual pack that does not stay balanced initially, so no weak cells ever in my assembled pack. That means for me, balance wires are not needed whatsoever.

But if you need them, for sure, go ahead and hook them up. But if you do and discharge, it becomes even more crucial that you never have an accidental disconnect of the main wires. You could end up pulling 10 amps through that balance wire connector.

So if you do have them attached all the time, I'd strongly recommend a solid soldered or crimped permanent parallel connector at the main wires.
Balancing mostly, but sometimes to monitor parallel packs..
ES IS SAVED! THANK YOU JUSTIN.

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Re: Parallel'ing balance leads???

Post by dogman dan » Jan 28, 2018 9:28 am

Ok, at least tape up those main plugs then. If you get a parallel disconnect, it can be hard on those tiny balance wires, trying to pull 10 amps.

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