DIY Li-Ion Battery Charger.

Well as I'm waiting for the "correct" charger to be delivered from china, I decide to try and DIY my own charger, and here's what I came up with...

[REVISED]
thanks to Benm and HIMNL9 for the suggestion to mod the battery itself!

What You need:
Soldering Iron
Wire & Solder (different colored wires will be helpful)
Old Cell Phone with charger and battery
2 small magnets
multimeter, or something to tell voltage

**Disclaimer** I am not responsible for any exploding batteries, or phones catching fire **Disclaimer**

1. Take the small magnets and solder a bit of wire to each one (few inches)
2. Disassemble cell phone battery CAREFULLY, there is a very small PCB you won't want to destroy, and you want to keep the plastic surrounding the battery in one piece so it fits back into the phone.
3. unsolder the battery from the PCB
4. Check the voltage of the battery using your multimeter
5. solder each colored wire to each respective joint on the PCB
6. place battery back in phone, attach magnets to battery, then attach charger.
7. Charge!!!

Pics!





also, make sure you don't let the magnets connect to each other, that wouldn't be pretty.

Thanks to photonaholic for the wires to make this possible

EDIT: i just realized this may be the wrong section for this, sorry bout that...

Naah, experiments and modifications can be considered a concept large enough for include also non-laser related experiments, i guess, and those batteries are used also in lasers, after all (anyway, only c0ld can decide about this), so probably your post is not in a too wrong section

Good idea for "recycle" a non-working phone (anyway don't try this with a working one, you can kill the charge circuit with big batteries ), but it was better if the phone can show you the charge status (at least, if it's not one of those models that requires the signal output from the battery protection circuit )



Edit: some of those phones shows you the charge status also with the color change of the recharge led, also if they are turned off, so maybe you still have an indication ..... just in case you don't have checked this

I suppose its possible, but not with all phones. Older ones might be the best candidates, as many of the modern ones also have some singal wires going to the batteries and arent that likely to charge just any battery you connect.

I am surprised those magnets still work tough, most of the neodymium type magnets lose their properties when heated to soldering temperatures.

well after powercycling the phone a few times, it finally started up and it just says "Invalid Battery", but it still charges it, so it's all good.

EDIT: never mind, it stopped charging, I guess i'll have to replace the cell in the original battery with these wires..

OK! finished modding everything to make a fully FUNctional charger with indicator status and revised first post with different instructions.

I suppose the solution with modding the phones battery will circumvent refusal to charge, at least if the original cells chemistry is comparable of what you are trying to charge.

One warning note though: The original battery might have a temperature sensor, which will obviously not read the external batteries temperature... something to keep an eye on when using this contraption!

i made a similar thread about home made battery charger but mine was using the ddl driver. obviously there won't be an auto shut off, so monitoring the charge based on math is critical.

This is a bad idea. Li-Ions tend to explode when charged improperly.


Not saying what you're doing is right or wrong, but for the sake of your house, your life and everyone's lives living in the house, I hope you're not wrong.

^Wow, that was violent.

I remember seeing a vid on the internet where they burned a piece of lithium (about 2g) that came from a LiPo battery they had disassembled. The burn was so intense that the whole frame became white and and it left a hole in the metal tin they where using as a crucible.

"Lithium is dangerous people!"

mfo said:

This is a bad idea. Li-Ions tend to explode when charged improperly.

Not saying what you're doing is right or wrong, but for the sake of your house, your life and everyone's lives living in the house, I hope you're not wrong.

Click to expand...

yea... good thing the proper chargers came in, but when i did use that charger, it was very closely monitored and i didn't let it charge for more than 30m to prevent something like that from happening.

Thanks for the sweet video about Li-Ions exploding too.