How to make Magnetic battery connectors

Magnetic battery connectors allow you to temporarily attach wires to new/untabbed/unusual size batteries without soldering. I use them to connect hobby RC chargers or other electronic stuff to cylindrical rechargeable batteries.

You can also use magnets and just stick alligator clips to them but where's the fun in that?

Here's how I made mine.

Start by gathering items that you'd need. These are: silicone wire (I used 16ga), neo magnets from FT (link), a couple short piece of heatshrink, and your connector of choice.


Start by stripping a short length of the wire end, tin the strands and add a length of heatshrink. (I'll explain what it's for in a minute)


Here's the tricky part. Stick the magnet onto a big piece of iron and tin a small area on the side. The large iron holds the magnet and absorbs the heat preventing it from demagnetizing. Soldering iron tips are coated with iron therefore it can get attracted to the magnet so be aware of that.


Clean with IPA to remove flux residue for the adhesive to stick well in the next step and solder the wires very quickly by simply heating them together to stick.


This is what the heatshrink is for. Since silicone is highly inert, adhesives won't stick to it. The heatshrink gives the 2 part epoxy something to hold onto and acts as strain relief.


This is what they should look like once the epoxy is added to keep the wires in place. You can also add your connector to the other end of the wires after this step.


To make it cure faster and harder, I use a big a$$ resistor and run power into it to make it heat up to about 40degC then stick the magnets to a steel ruler and put it on the makeshift hotplate.


Here it is completed. Makes a convenient connector for charging/testing odd size batteries.

Nice tutorial!

Is a neodymium magnet electrically conductive by itself? Or is it the nickel plating?

+1 for a great tutorial. This would have been very nice when i was testing diodes last week! I have more to test next week however, i will definitely do this. Taping leads onto battery terminals doesn't work very well...

Thanks!

Zeebit,
Since neodymium magnets are made from sintered metal, I assume the conductivity won't be very good so probably yes, I'm relying on the nickel plating. Be careful though when moving the wire after soldering, the nickel plating peels off very easily that's why it's necessary to use adhesives to keep the wire in place.

How much current can these magnets handle?

I haven't really tested but maybe 2A or so should be fine.

I love the big A$$ resistor :crackup: Fine tutorial thanks for sharing +4

Nice tutorial, I have used neodinium magnets but do you think soldering could cause loss in the magnetic properties.

+1

High temps will cause it to demagnetize that's why he stuck it to a big a$$ piece of iron to heatsink it while soldering.

FP,
Thanks! It's a 33ohm 220W resistor. Not a useful value for anything else so that's how it gets used.

Sinner,
Yep, as Zeebit said

Word of the day, "big a$$" haha

I somehow missed that part but it totally makes sense, big a$$ iron piece is what i am going to use. haha.

Yup, also helps keep it steady while you solder onto it so use a heavy one

You should post that big a$$ resistor over at the Ass Cheek Calibration thread.

I can't since it doesn't have cheeks so it does not meet the specifications to be posted there.

Perhaps if you presented it in a cheeky manner ;-)

As a side note, isn't nickel used as an underlayer when electroplating things? So, could these potentially be copper plated, since most of the current stays on the surface?

Very good toot oriole. Without the big a$$ chunk of metal, you would be amazed at how weak these magnets can become!

No idea about tge electroplating process but I don't think skin effect is an issue here since we're dealing mostly with DC.