DIY Li-Ion rechargeable battery pack

[eastern57]

This is how I make [most of] my Li-Ion packs.  I get the ones that are already protected, so they're easy to deal with.

These are Ultrafire 18500 (18mm x 50mm) with the integrated protection circuit.  And I solder them directly.  No problems (yet, of course).




First, these have a little coating (silicon, I think) on the positive knobs, you'll have to sand this coating off otherwise the solder will roll right off.  It's kind of hard to tell, but these have been sanded down... might be able to see the marks...




With a hot iron, melt a little drop on the knob.  Hold it for just a second or two so the battery tip can heat up and grab the solder.  Do this for the positive poles one each cell.  *The negative sides don't require sanding, but be careful not to hold it for more than a split-second... you'll see that it flows right on.




For the connection between the batteries, I use a little scrap of 22g to bridge the two.






And some leads for the ends as well.




Lastly, it all gets heat shrunk'ded together.



A few tips:
- Make sure your iron is ready to go (I use a 30w radio shack - works great for my purposes), and rosin core solder makes it easier too

- The wrapping around the battery is heat sensitive -shrink tubing- so if you heat the negative pole too long, you'll see the edges of the wrapping receed

- This is for PROTECTED CELLS ONLY!!!

- I highly recommend that you use a recharge port of some type with this set-up

- Funny thing about those protection circuits: they cut power off entirely when they deplete to a certain level - so don't freak out when your saber shuts off without warning... just plug it back in

Good luck!



eastern57 ;)

[Gil Gamesh]

Awesome DIY tut here!  I do this exact thing in my packs, works GREAT!  I've even had good results just using solder on the Pos of 1 batt and the neg of the other and securing them straight together without the use of a small scrap of wire!

I remember at first being REALLY nervous about applying heat to the batteries  ;D

[Jasten Skywalker]

This is great! Thanks a lot!

[eastern57]

You're welcome.  Hope it works out for you!

;)

[zayne]

Thanks, this is very helpful  ;)

will this work only for these batteries, or will it work for other rechargable batteries too?

[eastern57]

It will work with NiMh too... but if you use Li-Ion, make sure they're protected.

[zayne]

thanks  :)

[Jasher Kain]

This is awesome. Thanks so much. 8)

[Walky]

awesome tutorial
do you have a recommendation on the best place to purchase these
i see them all over the web from $6.30~$12.00 each
Thanx!

[eastern57]

awesome tutorial
do you have a recommendation on the best place to purchase these
i see them all over the web from $6.30~$12.00 each
Thanx!

I like these: http://www.lighthound.com/Li-Ion-Protected-Batteries_c_24.html

AW - haven't disappointed me yet.  One tip: don't let the few mah differences sway your decision... get the right battery for the project, and don't skimp on quality. ;)  okay, that's two tips.  ;D

Li-Ions are classified by dimensions: 18650 = 18mm x 65mm, 14500 = 14mm x 50mm, etc...

[Delmustator]

Eastern57,

I build mine pretty much the same way except I use leftover Taperwire for the connection between the batteries. It's 18 awg and flat so you can peel the adhesive backing off, heatshrink it,  and trim the edges to look nice and professional once it's soldered to the battery ends. Unfortunately unless you have some left over from a home theater installation, the stuff is pretty expensive at about $1.25 per foot.



But for this application, a little goes a LONG way.. I have extra if your interested...

P.S. I just checked out the link you provided for the batteries. Are those prices per each!? OUCHIE!! I usually get them in a 2-pack for the same price. But I have to wait for them to ship from Hong Kong...

P.S.S. Those AW 3000mAH 18650s are nice. Might have to get some of those..

[eastern57]

Right on, Del!  I actually use copper foil now, it works great!  And it's like $12 for 100 feet.  I like the AWs because they're more consistant and don't lose their charge... ultrafires do that sometimes. 

And I put those 3000mah ultrafires (not AW), in my k3gr1, and so far I haven't had any problems... I've recharged it; haven't really taken note of any significant run-time change, but at least they're not big red fails. :D

[bluerolla]

thanks for posting this i learned a lot. so protected means it's protected against over charging? so no need to add a pcb?

[Delmustator]

correct...

[JANGO FETT]

And I put those 3000mah ultrafires (not AW), in my k3gr1, and so far I haven't had any problems... I've recharged it; haven't really taken note of any significant run-time change, but at least they're not big red fails. :D

I have a set in my Anakin AOTC and have yet to recharge them. lots of runtime!