Balance charging a power tool battery ?

Thread Starter

Rufus Chucklebutty

Joined Mar 23, 2019
I have a Makita li-on 18 v drill with no charger I got for free, and I already have a Sky RC charger, so I would like to add a permanent balance charging lead to the battery, how do I work out the correct order for the balance leads ?

BL1830 battery
18650 cells
3.0 ah
7 contacts on balance charge port on battery


Joined Jan 18, 2008
The Sky RC charger is pretty simple -- I have one too.

Can you find the pinout for the Makita? I suspect they are similar, but plugs may be physically different. BUT, I wouldn't risk running on that assumption without knowing. You might be able to figure it out with a voltmeter.

Test one of your LiPo or other lithium packs for comparison.


Joined Jun 22, 2012
7 charge ports means 6 Cells In Series,
So one is 18V Output and one is Negative Output, the 5 in-between will be increasing in 3.6V steps. Get a Voltmeter and test the terminals.