Soldering Magnets

I have a Mag85 using 9 17500 cells in 3 adapters from fivemega. To get AW's cells to work correctly you must use the magnets he sends with the cells. Can you solder them to the top of 100's without harming the battery?? Or is there a better way to fasten the magnets down??

Moderators - Maybe the wrong place to post. Just move it to wherever since my email notifications don't work anyway.

You can harm the batteries if you apply too much heat.

If you are using rare earth magnets, which you probably are, you will destroy them by applying almost any heat.

If you want to permanently attach them, use conductive epoxy. There are numerous brands and types which generally use a high silver content as the conductor.

Supermagnets lose their magnetism when heated up to soldering temps. One type is a little better than the other but I don't remember which.

If you heat them to 176F (80C), they will permanently lose some of their magnetic properties.

If you heat them to 590F (310C), they will permanently lose all of their magnetic properties.

Edited to add: It really doesn't matter if they do lose their magnetic properties, because they will be stuck on with solder.

I agree, if they are permanently attached it makes no difference if they are magnetic or not. I am principally concerned with harming the batteries.

I'm ordering a bunch of the CBP 1650's and may solder some brass niples on. Why use magnets if your going to solder?? Why not solder some little brass nubs to the battery Holder???


Mac

cmacclel said:

I'm ordering a bunch of the CBP 1650's and may solder some brass niples on. Why use magnets if your going to solder?? Why not solder some little brass nubs to the battery Holder??? Mac

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Now, that is a fine idea. Thanks, no risk to batteries then.

I fly RC airplanes I have soldered many battery packs , li-ion's, NiMH's, and good ol NiCD's.


The heat is not good but,,, if you use a pencil type iron and let it got very hot!!! use radio shack .062 rosen core solder, you can do it with no problems at all.
Place the solder between the cell and the iron, when it melts it is done. About 1 second!! You can within about 2 seconds touch the spot you just soldered. You CANNOT use a gun type , they do not hold enough heat to be quik.

I have a SF P9 with a A19 extender I am running two 17650 ion's soldered end to end, then shink wrapped. I have two packs I made this way they both work great.

I use unprotected cells, when the light dims, (even a little) stop and charge. These ion cells are tougher than one would think.
I use 18650 ion's in a $7000 40% scale Extra 330 airplane, they are soldered and unprotected. They are the preferred battery in this hobby. (weight)
I accidently left my ignition battery on once and run the 2400 mah ion down to 0.468 volts, it came back and works fine. I would not use it for the controls , but if it fails the engine dies and the plane glides back to earth , no problem.

Ion's are not that scary.
jrplane

Where do you get the little brass nubs and where would you get the proper epoxy?

A small solder blob on the end of the cell is usually enough, you can also solder a thin washer to the + end of the cell if you want. Some times the washers can be a bit too much depending on the application.

You can find a bag of the small washers at home and hardware stores for around a dollar.

Later
Kelly

redbird said:

Where do you get the little brass nubs and where would you get the proper epoxy?

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I would'nt want to add the resistance the epoxy *May* cause. Also the conductive epoxy is $18.


Mac

cmacclel said:

I would'nt want to add the resistance the epoxy *May* cause. Also the conductive epoxy is $18.


Mac

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Ouch!! I guess I will figure something else out...