How to rearrange clamped cells after top balancing

[squowse]

So if the cells swell a bit when fully charged I would want to clamp them when the SOC is low. Say 10%?
Then they would need to be top balanced.
They would normally be arranged with the positive terminals all in a straight line for top balancing.
After that they would normally be arranged alternately positive/negative so you could connect them in series, so you would need to release the clamps?

Am I overthinking this?

 

[FilterGuy]

So if the cells swell a bit when fully charged I would want to clamp them when the SOC is low. Say 10%?
Then they would need to be top balanced.
They would normally be arranged with the positive terminals all in a straight line for top balancing.
After that they would normally be arranged alternately positive/negative so you could connect them in series, so you would need to release the clamps?

If you arranged them with all the positives in line for top ballance, then yes you would probably need to unclamp them and re-arrange them... But that should not be an issue (In my opinion). (This is what I would do).

If you are really concerned, there are a couple of alternitives:

1) Arrange them with alternating pos-neg but use cris-cross wires to hook them up in parallel for top balancing.
Remember that most of us don't top ballance at really high currents 10AWG interconnects with ring lugs would work for this just fine for a 10A top balance.


2) Arrange them with alternating pos-neg and top balance them individually. (I think it is @snoobler that advocates this).

Am I overthinking this?

In my opinion: Yes (Others may have different opinions)

 

[blutow]

I went the route of making the little jumpers to allow parallel charging while the cells are oriented (and compressed) for series charging. I figured that if there was ever a time my cells would be swelling, it's when I'm taking them up to max voltage during top balance. I wouldn't obsess over it, but I had some big clamps to compress the cells and it took 10 minutes to make the 6 jumpers out of some extra ring terminals and 10 gauge wire.

 

[squowse]

Sorry

If you arranged them with all the positives in line for top ballance, then yes you would probably need to unclamp them and re-arrange them... But that should not be an issue (In my opinion). (This is what I would do).

If you are really concerned, there are a couple of alternitives:

1) Arrange them with alternating pos-neg but use cris-cross wires to hook them up in parallel for top balancing.
Remember that most of us don't top ballance at really high currents 10AWG interconnects with ring lugs would work for this just fine for a 10A top balance.
View attachment 41557

2) Arrange them with alternating pos-neg and top balance them individually. (I think it is @snoobler that advocates this).


In my opinion: Yes (Others may have different opinions)

Sorry for late response. I'm thinking now that the clamping is for long term ands I shouldn;t worry about charging them without clamping a couple times as some don't even do it all.

I was thinking of the zigzag jumpers but I think it would be really easy to short a cell by accident with one of those.

 

[HRTKD]

Sorry

Sorry for late response. I'm thinking now that the clamping is for long term ands I shouldn;t worry about charging them without clamping a couple times as some don't even do it all.

I was thinking of the zigzag jumpers but I think it would be really easy to short a cell by accident with one of those.

There have been a few posts from forum members that experienced bloated cells during charging for the top balance process. I clamped mine during the top balance. My recommendation is to clamp the cells any time there is charge or discharge. Very minor charge/discharge rates _shouldn't_ cause bloating. But I'm good with playing it safe.

 

[blutow]

I was thinking of the zigzag jumpers but I think it would be really easy to short a cell by accident with one of those.

Anything you can do to minimize that risk is certainly good. I stuck red electrical tape with "+" next to all my positive terminals and I have not screwed up yet (knock on wood). The jumpers scare me a lot less than the bare bus bars. There isn't much uninsulated surface area on the jumpers. Whenever I'm installing or pulling the bus bars, I'm always concerned about a slip or drop.

 

[squowse]

There have been a few posts from forum members that experienced bloated cells during charging for the top balance process. I clamped mine during the top balance. My recommendation is to clamp the cells any time there is charge or discharge. Very minor charge/discharge rates _shouldn't_ cause bloating. But I'm good with playing it safe.

So do you use zig zag jumper leads? If not how do you rearrange the cells to series? Just unclamp and swap them around?

 

[squowse]

Anything you can do to minimize that risk is certainly good. I stuck red electrical tape with "+" next to all my positive terminals and I have not screwed up yet (knock on wood). The jumpers scare me a lot less than the bare bus bars. There isn't much uninsulated surface area on the jumpers. Whenever I'm installing or pulling the bus bars, I'm always concerned about a slip or drop.

the busbars are too short to short circuit a cell. pretty sure that's deliberate.

 

[blutow]

the busbars are too short to short circuit a cell. pretty sure that's deliberate.

You must be working with different cells than me. My bus bars are absolutely long enough to short across the terminals on my 272 lishen cells.

 

[HRTKD]

So do you use zig zag jumper leads? If not how do you rearrange the cells to series? Just unclamp and swap them around?

To go from 8p to 4s2p, I pull all the bus bars off, shuffle the cells, put the bus bars back on.

 

[Gazoo]

There have been a few posts from forum members that experienced bloated cells during charging for the top balance process. I clamped mine during the top balance. My recommendation is to clamp the cells any time there is charge or discharge. Very minor charge/discharge rates _shouldn't_ cause bloating. But I'm good with playing it safe.

Any bloated cell I have seen was overcharged but a couple of those could have been defective. Cell expansion and contraction is normal. I think there needs to be a distinction between what is defined as a bloated cell and a cell normally expanding.... And my cells do expand at very low .05 C rates.

 

[squowse]

To go from 8p to 4s2p, I pull all the bus bars off, shuffle the cells, put the bus bars back on.

you unclamp them?

 

[squowse]

You must be working with different cells than me. My bus bars are absolutely long enough to short across the terminals on my 272 lishen cells.

maybe you're right. It looks very close, I'm not going to test it!

 

[HRTKD]

you unclamp them?

Yes. I used the bus bars provided with the cells. I had something like 1.5 times the number of terminals.

 

[squowse]

Yes. I used the bus bars provided with the cells. I had something like 1.5 times the number of terminals.

no i mean do you unclamp the cells so that you can switch the orientation of the cells around?

 

[HRTKD]

no i mean do you unclamp the cells so that you can switch the orientation of the cells around?

Yes, I unclamp the cells. That is necessary to change from 8s to 4s2p.