View Full Version : I Want to make a Lithium Ion Battery Charger

06-22-2017, 8:08 AM
After pricing out a battery charger made specifically for lithium batteries I thought maybe I could save a pile of money and use a cordless drill battery charger. I found this Hitatchi 14.4V/18V charger on clearance for $ 15 bucks! I can't see why I can't Macgyver it to work. I just don't have the wiring know how to make it work.

I plugged this in and took a voltmeter and this is what I found out:
black to red 0 volts
black to white 3.3 volts
black to brown 5.0 volts
black to yellow 5.0 volts

So it looks like 13 volts total, which is right where I want to be. I don't know why the red wire has 0 volts?

I'm thinking if I twist the white, brown and yellow wires together that would give me 13 volts of charging? Am I correct in this thinking or am I missing something?

This is the battery I'm using and this is the spec sheet from the cordless battery charger


I'm not sure what these letters mean

06-28-2017, 5:12 AM
Honestly dont know
Im guessing that charger is for a banked battery. Or at least banked differently.
Most likely a different capacity and or load rating...

maybe lookup internal diagrams, compare the drill batt with the bike batt and go from there