Add protection PCB to Sanyo UR18650FM

Hi all,

I just crack opened an old laptop battery only to find that it's got six of those little babies marked as Sanyo UR18650FM L37A.

By the look of it, those are non-protected LiCo 2600mAh cells, not sure what L37A stands for, a discharge rate, ie. 3.7A, perhaps?

They all are ~3.77V which looks good I think, so now I am thinking how can I put them to some use.

I am wondering whether it's possible to purchase a bunch of protection PCBs and wield/solder them onto the batteries, wrapping them with some thin plastic afterwards?

Thanks!

L37A is their production date code.
K=2006
L=2007
M=2008
N=2009
O=2010
P=2011
37=produced in the 37th week

Please do more study before you go ahead.

Microa said:

Please do more study before you go ahead.

Click to expand...

Thanks for that, Microa!

Could you be more specific - what else exactly I should consider?

Li-ion batteries are dangerous if they are not handled properly. So that is why the famous brands of li-ion battery manufacturers only sell their cells to OEM manufacturers and do not sell them as a consumer product. You should clearly know what you are doing, otherwise you may be hurt. For example, the manufacturer doesn't recommand to solder directly on the battery's terminals. However, many folks here do solder the wire directly to the terminals. Also, you should consider is it worth the cost to modify
an aging battery.(just a question, I don't know the condition of your batteries.)

Thanks again, Microa,

I have read through the safety topics here on CPF and some on Battery University with regards to general use (ie. charging/discharging) but not so much on custom builds.

I am sure that excess of the heat during soldering is most likely not a good thing for batteries - so welding seems to be the remaining option - however getting a welding machine just for that seems to be a bit of overkill.

And it must be a very special battery spot welding machine. Don't even think about using a normal spot welder!

There is a good chance the cells are "dead" by industry standards, which is usually 70-80% capacity left or less, compared to the original 2600mAh. Almost all laptop packs I've cracked open have had cells with ~30-50% capacity left, and very high internal resistance etc.

Your batteries were salvaged from a battery pack. The batteries should have the wielded solder tabs on the terminals. Soldering on these tabs is no problem. Tinned the tabs and the wires first and apply some solder flux.

Bloody excellent point!!!

I am such an idiot - I have removed those solder tabs form 6 batteries already, better make sure not to do that with other ones!