Odd Milwaukee battery issue...

[Jason280]

I picked up a used Milwaukee 2557-20 3/8" ratchet with a 4.0 12v battery, and having some odd issues. The battery shows two "dots" on the charge indicator on the tool itself, but will not charge....charger will illuminate the green indicator, then switch to flashing red/green. I've tried it with a couple different chargers, with the same result. What's odd, it runs the tool just fine as is...so I am not sure why it will not take a charge.

 

[seber]

Bad circuit board on the battery.

 

[Showkey]

Or a bad or weak cell……….either way it’s not going to get better or fix itself.

Run the battery serial number through Milwaukee repair to see the age of the battery.

 

[Jason280]

I emailed Milwaukee with the serial number, I'll see what they recommend. If it *is* a bad circuit board, I wonder if its possible to scavenge one from another 12v battery...

 

[Marco40]

I had a bad 12volt Milwaukee battery and it was in the 1 year time frame of purchase and they sent a new one out. Sounds like the same issue.

 

[purplezr2]

Bad circuit board on the battery.

M12 batteries don't have a board in them. That is why the indicator is on the tools.

 

[dnschmidt]

If you're within warrantee you send it back to Milwaukee. If you're out of warrantee you're screwed. Life's a ***** and then you die.

 

[Odd-job]

measure voltage with a multimeter. If its under 7.2v or so it sounds like a cell took a $hit then go down the warranty route as per above. The 4.0s are also easy to pop open and measure the voltage of each cell. T8 tamper proof torx I recall.

 

[Showkey]

deleted

 

[darkzero]

I had that same problem on one of my M12 batteries. I noticed the 3rd feedback pin on the battery looked slight bent too far in. Worked fine in my tools though. Simply bent the pin outwards a bit & then it charged fine.

That was a battery that I suspected was counterfeit that I got my money back for anyway. Not saying that's what's wrong with yours but worth taking a look.

Edit: NM, come to think of it, it was the exact opposite, charged fine but sometimes wouldn't run tools & got 4 flashing lights on the tool.

 

[Rinspeed]

I've had a few new 18V batteries that wouldn't charge because of sitting too long and having low voltage. Simple solution is to give them a little voltage bump with a good battery. Only takes three or four 2 second bumps positive to positive, negative to negative, to boost the voltage up and they will start charging. There are a bunch of videos on Youtube to help you out. Safety glasses are probably a good idea.

 

[tab2]

Charge one full and then try to jump that one like you would a car for awhile. It worked when I ran an M12 down too far in a little kids power wheels ATV that I may or may not have modified.