I have 2 Makita batteries that won't charge. I saw a couple videos that show how to "jumpstart" them with another battery by connecting them together ++/--
It doesn't seem to be working though.
I have 2 Makita batteries that won't charge. I saw a couple videos that show how to "jumpstart" them with another battery by connecting them together ++/--
It doesn't seem to be working though.
Yeah that's not going to do anything to help bring back the batteries. Depending on the complexity of the type of battery pack, there isn't much you can do to revive them without replacing the individual cells and/or repairing or replacing the battery management board. You can't "jumpstart" a Li-Ion or Li-polymer battery. You could damage your good battery trying or in the case of Li-polymer you could burn the place down. Better to just replace those dead packs.
I think I've seen the same video. If I recall correctly, the guy says "jumpstart" for lack of a better term. He explained that the charger won't "see" the battery if it's completely drained. So you might have a battery that is still functional but the charger can't "see" it.
I'm way out of my ballpark here, but my layman's understanding is that he put the dead battery into a circuit with a charged battery until it had enough charge to be "seen" by the charger.
You seem to be knowledgeable in this regard. Does that have any merit?
Weird, I was trying to revive a few Dewalt's I have last few days. 8/10 charged up, 2 have dead cells, can only charge to 30% or so.
I had to do a +/+ -/- good to bad battery on 6 of them to get enough juice in there to get them going.
That's probably real good advice! I moved them outside just to be safe.
That could be many things from a bad controller board in the battery to a dead cell.
I'm starting to think the videos might be bunk.
Sometimes you can bring a dead multi-cell pack back to life like this, but you have to consider that the pack itself may not have any kind of charging controller in it - it may be in the tool itself. You can run quite a risk hooking an essentially unlimited current to what may be a dead short. If there is an onboard controller, it's probably smart enough no to turn on until some handshake is given, so your efforts are futile in this case.
I'd only connect two packs together like that as long as you realize there's a very small but measurable chance that you could wind up with a big hot fire.
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