Duct Tape Wrap

[Psyckosama]

Everyone says you should bind your LiFe cells to improve their lifespan. Just wondering it binding them together with a duct tape wrap, or putting pieces of thin plywood wood on each side and then binding them would do it?

 

[A.Justice]

Duct tape stretches over time. I wouldn't recommend doing that.

IMHO the easiest and cheaper (but not the best) way to compress cells is with plywood over both sides, and two or three very large hose clamps around them.

It would be better to have something that could be tightened to a certain spec, like long threaded rods around the pack to pull the wood or metal together.

 

[Boondock Saint]

Compressing a rigid housing or framework with ratcheting straps has been done. You won't be able to break the straps and you can possibly even tighten them a click more in the future if the need arises. They are inexpensive, get them at HD or HF. This will work if all 4 sides of the frame are not hard connected already. Sometimes with a ratcheting strap, you can't get the e x a c t spacing or pressure between two clicks, but you can mitigate this with a spacer.

 

[Gazoo]

Everyone says you should bind your LiFe cells to improve their lifespan. Just wondering it binding them together with a duct tape wrap, or putting pieces of thin plywood wood on each side and then binding them would do it?

What cells to you have. This has been discussed if using EVE cells.

 

[Psyckosama]

CATL 271ah

 

[Gazoo]

CATL 271ah

I don't know anything about extending cycle life using anything other than EVE cells. Does CATL say anything about it in their spec sheets? I know another member has said his Lishen cells do not expand and contract. It's important to get it right because too much compression is worse than no compression according to EVE. Also the SOC of the cells when they are compressed enters into the equation.

Do you plan to fully charge and discharge your cells at 1C rates every day? If you do your cells will last apx. 5.5 years and you will still have 80% capacity left if the spec sheet lists a 2000 cycle life. My point is the cells will probably age before they degrade due to capacity loss. Standard charge and discharge rates are usually listed at .5C in the spec sheets.

I have EVE's and am not concerned about extending cycle life. I do think it's important to mount the cells in a fixture of some sort to prevent terminal stress, and too much expansion for cells that expand. IMO if you are concerned about cycle life use conservative charge and discharge settings which will help extend the life of the cells, in other words keep the cells between the knees.

I haven't completed my pack yet and will be installing braided busbars. However the cells will be mounted in the same fixture they are currently mounted in. I lightly compressed my cells at a full SOC.

 

[Boondock Saint]

I haven't completed my pack yet and will be installing braided busbars. However the cells will be mounted in the same fixture they are currently mounted in. I lightly compressed my cells at a full SOC.

I like the damned simplicity of this. You use 5 threaded rods in that pack? Looks like you made this portable.

Is compression at full SoC the end game, or you going to discharge and compress again?

 

[Gazoo]

I like the damned simplicity of this. You use 5 threaded rods in that pack? Looks like you made this portable.

Is compression at full SoC the end game, or you going to discharge and compress again?

There are six 5/16 threaded rods, the top rod in the middle is hiding the rod beneath it.

The plywood is 1/4 inch. If one is going to apply more compression I would suggest .5 inch plywood. I have seen my plywood bow a bit when I was experimenting with more compression.

When discharged the cells are a just a bit loose. They will not be in a mobile environment so I don't need to worry about clamping them too hard.

The cells are sitting on a hand cart. Eventually they will go into a a box. Either this one or something close to it.

 

[Diysolar123]

I just use 3/4" cabinet plywood with threaded rods AND, most importantly...buy engineered compression springs so you know exactly what force you are applying by measuring the compressed length of the spring with what pressure you want.
The range to get some benefit is actually pretty wide; more than 5psi and less than 12 is "the window" to get some benefit. Also you will probably want flexible bus bars.
Charge you batteries to 50% capacity, then compress your pack to the midpoint pressure (I use 8psi). This is not an area where I am looking to "min/max" the system, just a little something hehe

 

[Boondock Saint]

Roger that. Agree on the .5" or more and I would think that if I use a torque wrench on the nuts to tighten, if I torque them all the same to 8 - 10 lbs, this would suffice? It will be in my cargo bay, but I don't want to super cinch it down in another box in case I need to disassmble or remove a cell in the future etc.

 

[Boondock Saint]

@ Gazoo - have you completed your box build? Do you have any more or any updated pics to show of your work?

It's crunch time for me.

 

[Gazoo]

@ Gazoo - have you completed your box build? Do you have any more or any updated pics to show of your work?

It's crunch time for me.

I haven't done anymore with it. Sorry.