7S10P Li-ion build ,, insulation?

Hey guys!

I'm putting together this battery here:


It's 29.4v 7S10P Li-ion 18650 as you can see from the photos. I have a 100A Daly BMS, a DIY fuse solution of 20A car fuses in parallellx3, and one shunt for an Amp/V meter. I've made the connections I needed to do; Now I need to make a box for the battery. I'm thinking of making one with a CNC machine that my friend has, out of thin plywood. And then later at some point I when I find a padded aluminium box, to put the plywood casing with the battery in there.

But for now the question that remains with me is what to insulate the battery with, inside the plywood. Also I'm wondering if you think it's a good idea with the plywood at all?

I have some gymnastic foam boards (PVA?) laying around, that I could use for insulation. But I'm not sure if it's the best idea -- any tips??

Cheers!

Under $20 waterproof and fits

Metal ammo cans are are awesome and I can fit 7s26p for about 66ah plus a usb pd port! one day I will post my design on here.

Do it

tjobapuerh said:

But for now the question that remains with me is what to insulate the battery with, inside the plywood. Also I'm wondering if you think it's a good idea with the plywood at all?

I have some gymnastic foam boards (PVA?) laying around, that I could use for insulation. But I'm not sure if it's the best idea -- any tips??

Cheers!

Click to expand...

Could you clarify 'why' you want insulation? Is it for spacing / to hold the cells in place or you're worried about heat or cold or other?

OffGridInTheCity said:

Could you clarify 'why' you want insulation? Is it for spacing / to hold the cells in place or you're worried about heat or cold or other?

Click to expand...

it's for spacing/holding the cells in place, as well as a little extra padding/protection for handling/bumps.
Are there any materials recommended for this use, and types of materials NOT TO use, that I should look out for? I'm afraid that the heat or something like that can be problematic.
Thanks!

tjobapuerh said:

it's for spacing/holding the cells in place, as well as a little extra padding/protection for handling/bumps.
Are there any materials recommended for this use, and types of materials NOT TO use, that I should look out for? I'm afraid that the heat or something like that can be problematic.
Thanks!

Click to expand...

Typically an 18650 battery that is used within standard specs (as apposed to max specs) doesn't get hot. Depends on charge/discharge current of course - but you can do a test and see for yourself. So heat/cool protection and/or fan (air-flow) is not likely an issue.

Compression is not needed as in pouch cells.

So this leaves primarily the physical moving around of the pack. I tend to use the 4x5 spacers (shaped to the container) and leave empty slots as the mechanism to hold the overall battery in place myself. Wood can burn so non-flammable would be a little better - but maybe your situation mitigates this?. There is such as thing as overkill so 'whatever' might fit the bill here

OffGridInTheCity said:

Typically an 18650 battery that is used within standard specs (as apposed to max specs) doesn't get hot. Depends on charge/discharge current of course - but you can do a test and see for yourself. So heat/cool protection and/or fan (air-flow) is not likely an issue.

Compression is not needed as in pouch cells.

So this leaves primarily the physical moving around of the pack. I tend to use the 4x5 spacers (shaped to the container) and leave empty slots as the mechanism to hold the overall battery in place myself. Wood can burn so non-flammable would be a little better - but maybe your situation mitigates this?. There is such as thing as overkill so 'whatever' might fit the bill here

Click to expand...

Alright! To be clear tho speaking about burning, are you thinking of the risk from outside, or is that a safety measure "from within", let's say -- considering the fact that li-ion batteries potentially can self ignite?
I saw Jehu built some batteries, separating inside the box two packs from each other with cardboard. Is that really considered OK in battery building?
I was imagining to make a padding, not to compress, but to fit it neatly in order for it not to bump around in there, and obviously protect from outside better. So for this material I was wondering if I need a particular fire proof material?
Thanks!

Whenever I see these sealed units it always concerns me that 'fast-charging' must be within a temperature range of 5 to 45 °C (41 to 113 °F)

tjobapuerh said:

.....cardboard. Is that really considered OK in battery building?....

Click to expand...

Cardboard has some fire resistant properties built in. Imagine if a cardboard factory caught on fire. Not the best. But theoretically should be kinda ok.
I use fish paper. Way better . The goal is to prevent shorts.
I also use neoprene to pad. You can buy rolls at home depot. Ask for toolbox drawer liners. Husky makes them.