Is it OK to use A123 stock tabs?

[tino_ale]

Hi all,

I've snagged a Dewalt 36V A123 pack and I'm going to make two 3S1P pack from it. I want to use them in a VXL Rustler for some serious power

I was wondering if I could keep the 4-points welded tabs that come stock to make my packs. I know in theory it would be better to remove them and solder "real" thick tabs, but really, that would make it so much easier to go with the stock tabs.

If you have tried and have an experience with this, PLEASE share your info!

Anyone know how much current the stock tabs can handle? I don't mind if it is not 100% optimal, as long as it works and run fine...

link to pack making : http://www.slkelectronics.com/DeWalt/hints.htm

[Arct1k]

The existing tabs work fine - note 3s1p will give you 9.9v not 11.1 like lipo.

Also note that the 1p will mean under load they will drop there voltage quite a bit...

PS I used this guide - works fine

[snellemin]

Leave the taps in place an don't twist the negative end button. Some people solder tabs on them. The stock taps can give you maximum current, but will get pretty hot if you pull massive amps continuously.

[MetalMan]

Don't even think about removing the tabs:
-the ends of the cells are aluminum, so you have to use special flux which is nasty
-since the ends are aluminum, they soak up a lot of heat which makes soldering more difficult

Using the tabs is perfectly fine, I've got 5 packs (40 cells total) soldered together using them.

[tino_ale]

Thank you a lot everyone for the valuable inputs

I'm going to make two 3S1P packs but they will be wired in parallel. I'm not making one single 3S2P pack because I have ordered a FMA 10S charger and it'll be able to charge both of my packs at once at around 8Amps

Stock tabs are fine - they were tested in this thread on RC Groups. See #18 for discussion on tabs - he calculates a tab resistance but his testing is for his planes current draw, 35amps.

This thread is also a great reference on building and using a123s. It encompasses about everything there is to know about rc useage of a123s, either directly or with links to other material.

http://www.rcgroups.com/forums/showthread.php?t=599316

[tino_ale]

Hi all,

Does anyone knows which size of shrink tube I need to make 3S A123 flat packs? (not stick but three A123 in parallel in a flat arrangement).

Anyone has a good online source for these heat shrink tubes, input very appreciated

thanks everyone

Last item on the page - specifically for a123s -

http://www.cheapbatterypacks.com/?si...07&pgid=shrink

[tc3_racer_001]

out of stock?

http://www.maxamps.com/products.php?cat=180

The prev link was for size.....

MA's shrink is sized 140mm. They also have it in clear if you backtrack up this link.

[tino_ale]

Just ordered a couple of foot of it. Thanks!
I can't wait to make my packs and I can't wait to see how they will be done charging in 15 mins. Already received the FMA 10S and it's begging to heat up some batteries

[VintageMA]

I am very curious how you guys balance your A123 packs (or if you even do).

[snellemin]

I use a A123 blinky to balance my cells. But if I don't drain my batteries to the last drop, they barely get out of balance.

Hyperion 0610i - the internal balancer. I'vr pretty much noticed the same thing - have to really pull mah out to see cells get out of balance much at all. If it wasn't so easy to do, I prob would skip balancing for a few charges.

[MetalMan]

I used to balance my A123s... Haven't in quite a while. With my packs I found that they would go out of balance during a charge, but then at the very end the cells would equalize, without the help of a balancer. Even if they do go out of balance, the cells can "bleed" off excess voltage while the other cells increase in voltage.