Which advice to follow???

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bobbill   100 W

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Which advice to follow???

Post by bobbill » Jun 16 2021 8:29am

Does one connect Parallel cells first, which seems to be preferred; or,
connect parallels second/last; or,
place both at same time.

Reason am asking, as I have two references: one says parallels first; then one says does not make any diff...am a noob at this and rebuilding packs that failed.

john61ct   100 GW

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Re: Which advice to follow???

Post by john61ct » Jun 16 2021 11:57am

Can go either way. Paralleled groups for equal capacity and matched resistance is most common and best for longevity.

But serial first may allow for higher power flow, IMO speculative.

Note those using sheet rather than strips or wires

are often doing both at once.

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pwd   10 kW

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Re: Which advice to follow???

Post by pwd » Jun 16 2021 12:02pm

If you are rebuilding/building a pack with (nickle, copper etc...) strips, I'd probably do the series connections first since those connections will carry the full pack current. In my case, I ended up using nickle sheet, so the series and parallel connection is all one piece.
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bobbill   100 W

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Re: Which advice to follow???

Post by bobbill » Jun 16 2021 2:19pm

John, and , pwd.

Thenks. We are, essentially, doing the same thing, I am not using strips, but

Seems, either way will work, if I meld the responses...which makes perfect sense. As I assume, once pack ia assembled, that is same connection-wise. What I mean is that the pack gets rechanrged and discharged, etc, as a matter of oourse or usage...if that makes sense? Am slowily learning.
Last edited by bobbill on Jun 16 2021 4:09pm, edited 1 time in total.

john61ct   100 GW

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Re: Which advice to follow???

Post by john61ct » Jun 16 2021 3:42pm

Yes once assembled the pack is one monolithic unit wrt the power +/- leads.

But for per-cell voltage monitoring, HVC LVC and balancing, you need to leave the cell/group-level connections accessible for meters, balancers, BMS, hobby chargers etc.

Most packs the BMS gets "buried" but IMO should be built so it is easily remove tested swapped out.

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spinningmagnets   100 GW

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Re: Which advice to follow???

Post by spinningmagnets » Jun 16 2021 4:17pm

All cells should be within 0.10V of each other, between the highest and lowest.

I am certain that it is best to make the series connections first. That means the series current has the least amount of resistance when running.

I am a fan of the copper/nickel sandwich method for series connections.

The parallel connections can be pure nickel with no loss in performance, and in fact, the cheap "nickel plated steel" ribbon works quite well for parallel connections.

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bobbill   100 W

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Re: Which advice to follow???

Post by bobbill » Jun 17 2021 5:16am

Thank-you both, Ron & John, for you r responses. I agree with your views.

But, if one has no choice, then what? Am using Agniusm's N.E.S.E. wonders and figure to form

Small packs, 10s4P and 3P, 36v units. Once were 10s3P packs, and the parallel and series connections are akready made, in the ones am using, so standing connections are what they are, save plugging in BMS wires, right?

All the cells are the same Brand, M-Amps and are now set to 3.61 to 3.69 volts, so once charged, as packs.
What makes a difference?

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agniusm   100 MW

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Re: Which advice to follow???

Post by agniusm » Jun 24 2021 2:34pm

bobbill wrote:
Jun 17 2021 5:16am
Thank-you both, Ron & John, for you r responses. I agree with your views.

But, if one has no choice, then what? Am using Agniusm's N.E.S.E. wonders and figure to form

Small packs, 10s4P and 3P, 36v units. Once were 10s3P packs, and the parallel and series connections are akready made, in the ones am using, so standing connections are what they are, save plugging in BMS wires, right?

All the cells are the same Brand, M-Amps and are now set to 3.61 to 3.69 volts, so once charged, as packs.
What makes a difference?
Most of the answers are probably more relevant to welded packs. You need to parallel first using mine. Just sort your cells with same voltage and load them into mudules, say 4 cells at 3.61V in one module and 4 cells at 3.69V into another. It does not matter if cells are not equal from series connection standpoint. BMS will even them out and there will be no inrush current like paralleling them.
You dont want big difference between them as it will take longer for bms to balance each module to the same voltage.

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Re: Which advice to follow???

Post by loneerider » Jun 27 2021 5:08am

Senior citizen/noob Wali here with a question on Paralleling.
Working on my 2nd build after a successful 1st one. 1500whub motor on a folding MTN bike.

Now I'm using a fat bike and six 12v 35Ah SLA batteries (bc the cost of a 72v pack made with regular Ebike batteries is tooo expensive)
So I decided to use the SLA. I learned the series connection method and am successful at that, my problem is not knowing how to parallel them? Can they be paralleled?

I've series them by straight neg2pos; I've made 3x 24v packs then series all 3 packs together to acheive 72v. Both worked just fine until I attempt to parallel all negs. then sparks literially start to fly. I'm powering a 5000w hub motor(capable of handling a 72, 82, 96v pack). I've seen YouTube vids of 3x 24v packs being paralleled, which increases AH but still remains a 24v pack bc the 3 packs are not series together. So am I reduced to using only one of the methods?, or find single 72v SLA batteries and just parallel them?

Man I need help BAD

john61ct   100 GW

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Re: Which advice to follow???

Post by john61ct » Jun 27 2021 5:42am

Seems worth starting a new thread

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bobbill   100 W

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Re: Which advice to follow???

Post by bobbill » Jul 01 2021 10:10am

@ Agniusm,,,Aye, anal me did just that...finally did something properly, me did.

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