Soldering the ends of batteries together

[SmurfTacular]

I am building a x4 AW 26500 triple P7 4D Mag build. And I want to make a battery pack that goes in and out all together in one piece. I thought about taking all the cells, lining them up, and shrink wrapping it. Would that hold all the cells together? What about soldering them in series? Would that be dangerous?

Is there any other ways of making a 4 cell battery pack?

 

[HarryN]

There are a lot of companies and people that make NiCd and NiMH packs all of the time, mostly by soldering or welding on tabs.

The challenge with all packs is the potential (actually, reality) that the cells will become unbalanced from each other. Even a small charge imbalance will get larger and larger each charge.

With NiMH / NiCd packs, it isn't that much of an issue, because you can slow charge the pack, and there is enough leakage through the cells so they will tend to largely rebalance. On Li based packs, that tends to not happen.

The approach with most Li based packs is to wire them with taps on each cell to the charger. These more sophisticated chargers will charge the overall pack, but also individually adjust the charge to each cell to maintain them in balance. This is very common in the R/C world, and a MUST for Li based packs. There might be some Li cell types that are less sensitive to this, but I am sure someone will comment on that.

I don't know enough about the detailed construction of the AW cells to comment on how they hold up to soldering, but it is outside of my soldering expertise to attempt that.

Is there enough room in the application to make a sort of sleeve or tube to hold the cells together enough for loading?

 

[SmurfTacular]

There are a lot of companies and people that make NiCd and NiMH packs all of the time, mostly by soldering or welding on tabs.

The challenge with all packs is the potential (actually, reality) that the cells will become unbalanced from each other. Even a small charge imbalance will get larger and larger each charge.

With NiMH / NiCd packs, it isn't that much of an issue, because you can slow charge the pack, and there is enough leakage through the cells so they will tend to largely rebalance. On Li based packs, that tends to not happen.

The approach with most Li based packs is to wire them with taps on each cell to the charger. These more sophisticated chargers will charge the overall pack, but also individually adjust the charge to each cell to maintain them in balance. This is very common in the R/C world, and a MUST for Li based packs. There might be some Li cell types that are less sensitive to this, but I am sure someone will comment on that.

I don't know enough about the detailed construction of the AW cells to comment on how they hold up to soldering, but it is outside of my soldering expertise to attempt that.

Is there enough room in the application to make a sort of sleeve or tube to hold the cells together enough for loading?

Ya, its for a 4D Mag. I would like to be able to take it out and plug it into a hobby charger all in one piece.

 

[kramer5150]

You need solder tabs. A the simplest level its nothing more than thin copper strips cut to length. Flux and tin the ends and then solder that onto B+ and B-. Then you gently fold the strip over onto itself to line up the cells in a row. Shrink-wrap them into a tube and you're all set.

You can get copper sheet stock at any well stocked RC hobby shop. Just cut it to shape with tin snips or those sharp utility scissors that cut pennies.

:thumbsup:

 

[jasonck08]

You may find this video informative. It shows you how to solder batteries end to end. I dug it up a year or so ago when I needed to make a battery pack.

You will need a hammer head soldering tip and a good powerful soldering iron (40-60W+).

@ about 1:50 it will show you how to solder end to end, but I recommend watching the rest of the video.

http://www.youtube.com/watch?v=IelXfcrIXCc&feature=related

 

[HarryN]

Hi - just make sure you can connect each cell to the charger individually for balancing.

 

[MrNaz]

I recently found what I think is *the* way to join batteries end to end. No soldering, no heating. No risk at all, and should be fine for holding up to stress during shrink wrapping etc.

http://www.epoxies.com/elec.htm

Enjoy!