Dewalt battery charging problem

300jk · Dec 2, 2020

So I have mostly Dewalt 20v lithium tools. Took the battery
out of my leaf blower to charge it before putting it away for the
winter. 5 amp hour battery that was not completely dead
when I used it last week. It is now completely dead and won’t
take a charge. It’s not cold or hot, and hasn’t really seen that
much use. It’s showing totally dead and won’t charge. Any
thoughts? It’s a pretty expensive battery to replace and I
have no idea what happened. Charger works fine on other
batteries.

M-MAN · Dec 2, 2020

If you have a manual battery charger put it on 12v and touch the positive and negative terminals for a couple minutes. It will put enough juice in the battery for it to take a charge.

IowaJohn · Dec 2, 2020

I got 2 new dewalt 20v 6 amp batteries from home depot, got a really good deal. Went to charge them, 1 was fine the other showed both red flashing and amber lights in the charger. Would charge a little but not run anything very long. According to our service shop it was shot. Fortunately it was under warranty. Just 2, 150 mile round-trips.

oliverplow · Dec 2, 2020

Do you have another battery? Take two wires and hook on the neg to neg and pos to pos with a charged battery for about 15 seconds. It will even make a small spark. It will give it just enough charge so the charger will start charging it again. There is a youtube video showing how to do this. I have revived a couple of them doing this.

Greg1959 · Dec 2, 2020

I have one doing the exact same thing. Thanks, will give it a try tomorrow.

Stephen Newell · Dec 2, 2020

Dewalt tools are just crummy. As high as the batteries are it would be cheaper in the long run to start over.

guido · Dec 2, 2020

Hello Greg1959,

It will not work,

Guido.

Dusty MI · Dec 2, 2020

I have been happy with my 12v DeWalt drill motors.

Dusty

guido · Dec 2, 2020

Hello 300jk,

The pack may have a cell which is dead or the protective circuit kicking in.
If the charger sees no volt it won't charge. It needs to be taken apart and the cells individually checked.

It's a high capacity pack, it will be a series and parallel cell configuration. A volt meter will tell the story. If you find dead cell, then you know that is why it's not charging. If all the cells test ok, you can try charging them across the pack terminals.

Usually though, it's a bad cell that is not completing the circuit,

Guido.

bc · Dec 3, 2020

(quoted from post at 22:36:20 12/02/20) Hello Greg1959,

It will not work,

Guido.

What Guido said. I couldn't make it work. I've even tried jumper wires from a good plugged in battery to the bad one and still wouldn't take a charge. Worth a try I suppose. I've put then in a baggie in the freezer from 30 minutes to a day or more and that didn't help. Not sure why running a battery down would cause a cell to go bad though. Left one in a light that was on all night till it went dead.

guido · Dec 3, 2020

Hello bc,

The reason it did not work, is because the charger is no more then a power supply, going
to the control board inside the pack. The board has balance leads for each cell, so they all get charged to the same voltage. Not all chargers are that way. Some packs have the
balance plug, that fits to the one on the battery pack. Plus the high plus and minus main leads.

If you still have the pack, take it apart. If the cell protector was activated, and the
cells are all good, you should be able to charge the pack. Use the plus and minus leads
at each end of the pack.

If you have a weak cell, the rest will take a charge. Sometimes just one cell goes bad, and replacing it will bring the pack up to speed,

Guido.

Dewalt battery charging problem

300jk

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M-MAN

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IowaJohn

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oliverplow

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Greg1959

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Stephen Newell

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guido

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Dusty MI

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guido

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bc

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guido

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