A123 battery soldering help please!!

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bowhunter
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A123 battery soldering help please!!

HI GANG
I have an A123 lifepo4 battery – AHR32157-M1-B .
I need to solder 12 gauge silicone wires onto the terminals as there is no clip or screw attachments .
need advice on the correct and safe way to do this

scaru
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The safe way? Spot welding. In general it is a bad idea to try to solder onto a battery yourself, it is often very hard to get the solder to stick, and even if you do the heat from the soldering iron can easily damage the battery. 

I would recommend seeing if there is a place around you that rebuilds battery packs, you may be able to talk one of them into spotwelding some tabs onto them for you. 

comfychair
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If you try to lay the tip on the cell and wait for it to get hot enough to melt solder, you will cook it. Instead put some flux on the cell, load up the tip of the iron with a blob of solder, give the iron a few seconds to heat up, then dab the solder blob onto the cell. Doing it like that only has heat applied to the cell for a few seconds.

Practice on dead alkalines until you get good at it.

Aftrburnr
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Nice tip comfychair, thanks! I might wanna try something similiar but for battery pack rebuilding.

tabetha
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Why use HEAT, on the solder ?, I would cold solder it, that’s what I do, buy yourself a COLD SOLDERING IRON, job done no heat no risk.
Tbh I always soldered onto batteries with NO PROBLEMS at all, just make sure to deeply scratch the battery surface so the solder will stick, try and use UNFLUXED solder, but wipe the battery terminal with PINE TREE WAX first, this is the best flux you can get!!, then tin the wire lay onto battery and melt, it will take instantly.
The cold soldering iron, isn’t a “iron” in the traditional sense, it uses high frequency to melt solder, so good you can touch it instantly after wards and feel no heat.
tabs

jonhobart
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Tabetha,

Any links on what you are talking about for the cold solder?

texaspyro
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The A123 batteries use an aluminum case. There is a thin nickel layer on one end… scratch it too much and it won’t stick. The other end is easier to weld to… it’s still rather hard to do.

Ultrasonic bonders cost BIG bucks. So do decent spot welders. I built my own spot welder… http://endless-sphere.com/forums/viewtopic.php?f=2&t=2633&hilit=megadonk...

Aftrburnr
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@johnhobart If you google weller cold heat soldering iron, you’ll find a bunch of info and some youtube vids

texaspyro
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Aftrburnr wrote:
@johnhobart If you google weller cold heat soldering iron, you’ll find a bunch of info and some youtube vids

The Weller Cold Heat iron is not the same as an ultrasonic welder. It is just a soldering iron that uses a ceramic time. Very fragile, rather crappy…

Aftrburnr
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I definitely know the difference between the 2. Would love to have a CD welder to do some battery pack rebuilding. I was just trying to help out with where more info on the Cold Heat soldering iron cold be had.

relic38
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I recall that A123 cells come with tabs welded on already. I guess there is a no tab option too? The ones with tabs are the easiest to solder since the tab accepts solder easily.
Edit: Nevermind, I’m thinking of Moli cells.

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bowhunter
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thanks for the tips
comfychair – when you load the tip with solder – then you press that onto the top of the cell and then place the wire into it, or lay the wire on first and then put the solder onto that and the batt top.??
do you pre tin the batt top first,etc?

comfychair
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Don't tin the cell, just a drop of flux. Tin the wire to keep it from going all hairy. Lay the wire on the cell, then apply the dollop of solder.

If you leave it too long it'll suck the heat out of the iron and stick, if you do it quick enough while the solder is still hot it'll flow out and be nice and smooth. If it chills and the iron sticks it'll be lumpy and grainy. And less time is always safer for the cell.

I wasn't joking about practicing on dead alkalines, btw. It helps! Smile

bowhunter
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Comfychairs technique works great on nickel cased batts BUT my a123 – 31257 cell has a square “nut” on the end and it is aluminum so the solder would not stick.
SOOOOOO- I drilled and taped an experimental 2-56 hole in one corner of the nut/washer but I am a little spooked about going this route.
this so called nut/washer is considerably less than 1/8 in thick, underneath it is a plastic type washer and the nut appears to be held on by an aluminum post/rivet in the centre of it. I do not understand why that plastic washer is underneath that nut and worry that if I drill thru it to the aluminum batt top underneath it may short???
you would think that the entire aluminum end would either be pos or neg and that you could not short that out.

perhaps I would be better off to just drill and tap the aluminum post that holds the nut onto the batt end but am unsure how deep I could tap down that post until I would be in the guts of the battery.

any thoughts / ideas????

bowhunter
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bumping this thread along to see if anyone has some knowledge on my above problem/questions

relic38
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Can you post a pic or two of the battery ends, where you want to solder on to? If there is significant mass, it could be a problem.

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bowhunter
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the square nuts/washers I speak of are approx. 5/8 in square by -1/8 in thick, they are fastened in the middle by a round pin that appears to be a rivet, underneath the square washer is a thin clear plastic washer.
the washer and the battery top are aluminum with no nickel coating that I can tell of.
since these batts were designed for the electric car,etc market I guess these ends are for that purpose.

I do not know how these batts are constructed but was wondering if it is okay to tap that aluminum pin for a 4-40 screw to fasten my wires on with. I just do not know how far in I dare drill / tap to before I get into the batt guts??

Fritz t. Cat
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This thread is making me think I am on the right track going back to alkalines for my current project. Something that can’t stand soldering doesn’t really belong in my pocket.

Flashlight designers should look at lighthouses and pottery.
这些谁设计的手电筒应该看灯塔,以及在陶器。

relic38
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Fritz t. Cat wrote:
This thread is making me think I am on the right track going back to alkalines for my current project. Something that can’t stand soldering doesn’t really belong in my pocket.

Soldering temperatures… Exactly how hot is your pocket? Big Smile Wink

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Fritz t. Cat
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relic38 wrote:
Fritz t. Cat wrote:
This thread is making me think I am on the right track going back to alkalines for my current project. Something that can’t stand soldering doesn’t really belong in my pocket.
Soldering temperatures… Exactly how hot is your pocket? Big Smile Wink

That was a dumb remark, sorry.

Flashlight designers should look at lighthouses and pottery.
这些谁设计的手电筒应该看灯塔,以及在陶器。