Soldering leads to 18650s

[dr g]

Yes there are other discussions around the web about this, but the camps seem sharply divided between it not being a big deal and those who wouldn't touch doing it with a 10 foot pole.

What is your experience/opinion? I'm looking to do this, specifically, to Panasonic hybrid batteries.

Is there a better alternative as far as spring contacts or maybe (solid) screw contacts? For a box type mod.

 

[DrMA]

Not a problem at all. Use a good iron with a large flat tip. Pretin your wires and have them handy.

Then, set the temp to 700°F, put some flux on the battery and pretin the iron tip. Have a good sized bead on the tip and use it to heat up the battery contact where you added the flux. It should take less than 10 sec before you see the solder flow onto the battery contact. At this point, insert the pretinned wire into the molten solder and keep the heat on until the solder flows on the wire (less than 1 sec), then remove heat and hold the wire in place until the solder hardens.

Disclaimer - a good soldering iron with a large chisel tip is a must. Don't attempt this with a cheap Radioshack iron.
In case you're wandering - yes, I've done this many times to LiPo's, NiCd, and NiMH batteries. Here's a 4-series pack of NiCd's I made recently for another hobby, not related to vaping.

 

[dr g]

Would it be better to go higher than 700 deg if possible?

10+ seconds seems kind of long compared to some of the advice I've seen.

 

[DrMA]

Hotter wouldn't help. If you go too much past 700F you risk damaging your iron and regular Pb/Sn solder won't stick to the tip.

It's OK to go a little longer than the textbook 6s when you're heating up a huge chunk of metal like the battery ends. The only problem might be if you're using protected battries, as the heat might damage the protection circuitry installed at the positive end of the battery. Fortunately, the positive end is smaller and will heat up much faster than the negative. And you should be using unprotected IMR batteries for vaping anyway

 

[dr g]

Well regarding other chemistries, people seem to believe Li-Ions are much more to be careful with than NiMH or NiCd (which people consider safe chemistries) ...

Have you soldered Li-Ions per se?

 

[Ec!g]

Well regarding other chemistries, people seem to believe Li-Ions are much more to be careful with than NiMH or NiCd (which people consider safe chemistries) ...

Have you soldered Li-Ions per se?

I have, successfully I might add. Usually to add protection boards but identical concept as pack building.

Working quickly and with high heat is recommended.
Flux is your friend. Pre-tin both leads and cell posts.

Also one thing I didn't see here mentioned, the scuffing(scratching/scraping) of the posts. Helps the solder adhere much much quicker and a much better bond.

 

[dr g]

You on board with the 700 degree recommendation?

 

[mamu]

I have a Weller 35-Watt soldering iron (tip temperature 850°F) and use it without problems when soldering leads to battery ends.

-Working quickly and with high heat is recommended.
-Flux is your friend.
-Pre-tin both leads and cell posts.
-scuffing(scratching/scraping) of the posts.

All these tips are important for success. Plus the more scuffed up the posts are the faster and better the adhesion when soldering. I scuff/scratch the posts using a dremel... very lightly and very carefully.

 

[DrMA]

....
Have you soldered Li-Ions per se?

Yes.
LiPo's, Li-Ion's, LiFe's
round cells and flat cells, of all sizes: smallest 160mAh, largest 2600mAh
All unprotected though...

 

[dr g]

Have you seen such a thing as a nickel plated aluminum tab that can be soldered with normal solder?

 

[bapgood]

Have you seen such a thing as a nickel plated aluminum tab that can be soldered with normal solder?

I'm confused....are you talking lipo cells now?

 

[dr g]

I'm confused....are you talking lipo cells now?

Yeah, darn, I kind of jumped the tracks from the other thread about the flat lipos!

 

[bapgood]

Lipo tabs have been all over the board in my experience. Best is to try to keep solder on the tabs if you are messing with a previously soldered cell, like changing a series pack to parallel. Aluminum solder paste/flux can make all the difference in the world on some tabs, others it doesn't seem to help at all, other tabs solder as easy as pie.

Other than the above which probably only muddies the water more, the previous listed soldering techniques hold true.

 

[DrMA]

Yeah, I've seen plated tabs that can be soldered with regular solder. But it's hard to tell which is which, so i just use special aluminum solder and flux on all aluminum looking tabs on flat cells (unless they're pretinned). The round cells tend to have zinc or tin plated tabs that are easy to solder with regular rosin flux and Pb/Sn.

 

[dr g]

Yeah I've soldered the rounds repeatedly with no problems since they have that little strap, but I have yet to do anything with this 2200mah flat.

 

[fourtytwo]

Why not go with RC style battery connectors?
I have always had good luck with Anderson Power Poles Amazon.com: 30A Power Pole Connector (4 Black, 4 Red) Anderson-Sermos: Toys & Games and Deans style Deans - Plugs.

 

[dr g]

size. those eat up valuable case space. and of course to use those you'd have to solder to the cell anyway.