Soldering the Li-Poly cells

Community PCB Design
1

I wasn’t sure if this was the place to post this question, but I figured it wasn’t a “work in progress.”

I’m curious as to soldering the Li-Poly individual cells. I know that extended heat from soldering can damage Li-Poly cells, is there anything I need to know about soldering the tabs? Is there any heat/time combination that I should abide by?

Let me rephrase: I’m looking for anyone on here that has worked with them and I’m asking for personal feedback. How easy was soldering the tabs? I’ve never worked with soldering Li-Poly cells before, so this is why I’d like to know from someone who did: what temperatures and times they used, maybe even their favorite lower-temp solder for working with stuff like this.

2

Well, It’s usually a good idea to look at datasheets for this kind of info.

According to the [datasheet for the 1200mAh battery that is linked to from the Sparkfun [product page:

9.3 Tab connection

Ultrasonic welding or spot welding is recommended to connect battery with PCM or other parts.

If apply manual solder method to connect tab with PCM, the notice below is very important to ensure battery

performance.

  • The electric iron should be temperature controlled and ESD safe;

  • Soldering temperature should not exceed 350C

  • Soldering time should not be longer than 3s, keep battery tab cold down before next soldering;

  • Soldering times should not exceed 5 times;

  • Directly heat cell body is strictly prohibited, battery may be damaged by heat above approx. 100C.

The 2000mAh datasheet says the exact same thing.

Does that answer your question? :wink:

Keith](http://www.sparkfun.com/commerce/product_info.php?products_id=339)](http://www.sparkfun.com/datasheets/Batteries/UnionBattery-1000mAh.pdf)

3

there are DIY spot welders that you can find on the web… :wink:

but soldering would be best if you don’t have to do this a lot of time…

4

If I were to solder to the tabs on a cell like that, I would probably wrap the cell in a cool rag, making sure to have it close to where the tab connects to the rest of the cell.

I would also make sure my iron can get near that max temperature. If your iron is too cold, you’ll have to hold it on the tab much longer to get a good joint, compared to a hotter iron.

5

I solder to these things quite a bit. They are a pain, as it doesnt really stick well. I usually put a little heat sink clamp on the battery, place the wire on the tab, and drop a glob of solder onto it. I try to avoid direct heat.

6

Perfect, thanks for the tips. This is exactly what I was looking for.