Using Tape to Compress LifePo4 Cells

[Henderson]

Hi there, I'm wondering if its ok to use non-conductive tape to compress my cells. Let's take for example a 3P16S battery using LifePO4 prismatic cells. I'm thinking that each 3P cell can be wrapped in tape and then 16 of those tape-wrapped 3P cells then connected in series to complete the battery build. I will have them placed in a box but hoping this method is considered acceptable and would allow me not to have to use threaded rod. I'm looking at using this type of tape from amazon https://www.amazon.com/gp/product/B07HB9M3ZP/ref=ox_sc_saved_title_3?smid=A3ASOL2BV6TI90&th=1

Would appreciate this group's thoughts and feedback on this approach. Thanks in advance.

 

[MisterSandals]

I am in the camp of firm constraint rather than actual compression. So my thought is that its ok except for the ends where they could bulge very easily. If you can put something like 7/16 plywood or better, on the ends, you'd be just fine.

 

[timselectric]

I agree with @MisterSandals for grade A cells.
But believe in slightly compressing Grade B cells.
They are more likely to swell, easily.

 

[A.Justice]

I also agree with MS. I use Kapton tape for my small cells, and a combination of Kapton / plywood and hose clamps for anything over 100ah. No actual "compression", just a firm grip on the cells when they are mostly discharged. I have some packs in off-road vehicles that are quite literally thrown around, and the tape and clamps have held on better than I could have hoped for, nothing has come apart... yet. ?

I'm sure there's somebody who will argue that actual compression is "better", and it probably is, but IMHO, for most use cases, good tape and some solid stabilization will be enough. The cost / benefit of "proper" compression just isn't worth it to me.

My advice would be to use a tape that doesn't stretch, like Kapton.

 

[Woody]

Here’s a Lithium Ion Polymer battery bank that had two pouch batteries taped together when one of the battery cells failed. (Yes I know it’s not the same chemistry or packaging as LiFePO4. I’m just providing these photos as an example of how taped pouch batteries reacted upon bloating. One can extrapolate proportional response to LiFePO4 cell bloating.)

This battery bank was left in a cabinet in a travel trailer for several months unattended when I found it bloated. It was fully charged prior to placing it in the cabinet. Something internal to the battery failed. As one can observe the tape poorly contained the expansion. The take away is that tape isn’t the best solution.

 

[MisterSandals]

It was fully charged prior to placing it in the cabinet.

Storing them fully charged is their achilles heel.

 

[Henderson]

Thanks all. I appreciate the feedback.

 

[A.Justice]

Here’s a Lithium Ion Polymer battery bank that had two pouch batteries taped together when one of the battery cells failed. (Yes I know it’s not the same chemistry or packaging as LiFePO4. I’m just providing these photos as an example of how taped pouch batteries reacted upon bloating. One can extrapolate proportional response to LiFePO4 cell bloating.)

This battery bank was left in a cabinet in a travel trailer for several months unattended when I found it bloated. It was fully charged prior to placing it in the cabinet. Something internal to the battery failed. As one can observe the tape poorly contained the expansion. The take away is that tape isn’t the best solution.

I wonder what would have happened if it were compressed. Venting maybe? That pressure has to go somewhere.

 

[Tim Tim]

I am in the camp of firm constraint rather than actual compression. So my thought is that its ok except for the ends where they could bulge very easily. If you can put something like 7/16 plywood or better, on the ends, you'd be just fine.

Agreed, except I stole some of the poly chopping boards from the kitchen which my wife is still looking for .
The blue, green, red, yellow and white also add some colour and the board handles make great handles for my caravan batteries.

 

[Will Prowse]

Storing them fully charged is their achilles heel.

Especially lithium polymer. Gas formation occurs in only a few weeks if stored in a hot car. I have a few boxes of bloated packs for this reason.

 

[rcrracer]

Max internal volume/area with min/fixed external length is a sphere/round and not a rectangle.

 

[Nobodybusiness]

Hi there, I'm wondering if its ok to use non-conductive tape to compress my cells. Let's take for example a 3P16S battery using LifePO4 prismatic cells. I'm thinking that each 3P cell can be wrapped in tape and then 16 of those tape-wrapped 3P cells then connected in series to complete the battery build. I will have them placed in a box but hoping this method is considered acceptable and would allow me not to have to use threaded rod. I'm looking at using this type of tape from amazon https://www.amazon.com/gp/product/B07HB9M3ZP/ref=ox_sc_saved_title_3?smid=A3ASOL2BV6TI90&th=1

Would appreciate this group's thoughts and feedback on this approach. Thanks in advance.

I used a ratchet strap to compress them.
Then used Kapton tape to secure them.
Removed ratchet strap.

Never had an issue.

YMMV..

 

[bass-o-matic]

I am in the camp of firm constraint rather than actual compression. So my thought is that its ok except for the ends where they could bulge very easily. If you can put something like 7/16 plywood or better, on the ends, you'd be just fine.

Hello again. I love this solution. Elegant. No bolts or crazy boxes. Question: Once I make my plywood "end caps", I assume I just wrap the tape around them as well to hold them in place. EG. Just wrap everything!

 

[bass-o-matic]

My new 280AH came with some sheets of thin fiberglass, yellow, I assume for fixture. But I also have 2mm EVA.... which would you go with?

I made 5/8 Ply end caps to boot.

 

[bass-o-matic]

Check it out... Fiberglass in the middle, EVA and Plywood on the ends... ton of Kapton. I used some wood clamps ... so "snug" not squished. Now I'm ready for a Top Balance.

 

[Skinny76]

Check it out... Fiberglass in the middle, EVA and Plywood on the ends... ton of Kapton. I used some wood clamps ... so "snug" not squished. Now I'm ready for a Top Balance.

That is what I'm thinking I'll do. I like how my plywood/threaded rod construct works to keep everything secure, but it is a pain to make for just a small 12 volt setup.