Frames for assembling battery packs from 32xx0 cells

While modifying yet another device, I needed some frames for assembling battery packs from 32700 cells. I ordered some, received them, and thought, why not put together a short review on the subject?


For several years, I had two reviews of similar frames, in 1-cell and 3-cell sizes, but for the more common 18650 cells, so I already had a pretty good idea of what they were and how to search for them.

I planned to use them to assemble a battery for the UPS in one of my devices. I first ordered the larger ones because, for some reason, I thought they’d be better and more suitable. But when they arrived, I realized I’d made a mistake and that the smaller ones would have been more convenient. So now I have a pile of battery frames :)

I ordered them from the same store, but from different listings. I ordered from there the second time because delivery was very fast and the packaging was decent: the frames were wrapped in film instead of being dumped loose into a bag, as sometimes happens.


I ordered the 2x3 version first, hoping to combine them somehow for a 4-cell battery, then ordered the 2-cell version.


The store page also had a 3-cell version. I think a 1-cell version exists somewhere too, but I haven’t come across one in the 32 mm size, and I haven’t looked for one either.
Besides the 18 mm size, there are frames for 21 mm cells. For 32 mm cells, I’ve even seen 5x8 versions, which would let you assemble, for example, a 4S10P battery.

I’ve seen photos of battery packs without frames several times in reviews and comments. I’ll say right away: it’s not a good idea to do that. And if you do, you need to install spacers so the cells don’t touch each other. Frames serve two purposes:
1. They make the assembly rigid.
2. They create a gap between the cells.

Rigidity is important if the battery operates in a vibrating environment. The gap keeps the cells from shorting against each other, since with enough heat the heat-shrink tubing can simply slip off or get damaged by something.


The 2x3 frames cost $0.49 each, plus $0.83 shipping. There’s also a 5-piece lot for $1.99, plus $0.83 shipping.
I ordered 8, and they cost me $4.97 in total.


Dimensions, excluding the protruding parts, since those can simply be cut off after assembly.


I wouldn’t call the manufacturing quality absolutely excellent, but it’s very good.
The frames have a top and a bottom: the top, which faces outward, has slots for joining them with a strip.


They connect using the familiar dovetail joint.


They fit very tightly, so taking them apart later is quite difficult.


The 2-cell frames are cheaper: a 5-piece lot costs $0.86, plus $0.83 shipping. You can also buy them individually for $0.29 each, with the same $0.83 shipping. So if you need 4, it’s cheaper to order 5 than 4.
Two lots of 10 cost me $2.59.


Since this is a double frame, its length is the same as the width of the 2x3 version. The thickness and hole diameter are unchanged.


The molding quality is also good: everything is neat and well made.


The connection method and even the spacing between the clips are the same.


This may matter to someone: a 2x3 frame weighs slightly less than three 2-cell frames.


The frames are fully compatible with each other, so you can make more than just rectangular layouts like 2x3+2—you can make more complex ones too.


There’s just one detail that may be important: if you add a 2-cell frame lengthwise to a 2x3 frame, its clips end up facing the wrong way. That doesn’t matter when assembling a 4S2P battery, but if you’re planning a more complex layout, you should first work out how the frames will fit together.


The gap between the cells is about 2 mm, actually closer to 2.3 mm. During assembly, it seemed that the batteries fit tightly on the negative-contact side, while they slide in very easily on the positive-contact side.


There’s also plenty of room for the nickel strip. I haven’t welded anything in the photos yet, since I’m still getting everything ready.


And here’s how the 12-cell and 4-cell battery packs are supposed to look. Most likely, I’ll assemble a 4S pack for my device and a couple of 4S2P packs to replace the batteries in standard UPS units.


That’s all. I can say I liked the frames, as well as the delivery speed. If you need them and the price works for you, go ahead and buy them. As for the price, I should mention that when I ordered, I couldn’t find any cheaper listings, but the shipping destination makes a big difference, since shipping costs sometimes change.