Dead Dewalt Battery Revivial

[opps]

As with some smart lead-acid battery chargers,

But they don't risk thermal runaway... You probably know more about this than me, but I recall NiCads having a cut out point after which, for safety reasons, they would not accept a charge.

 

[Mr Chibs]

From where was the pressure being released? The end of the cell?

I am not sure that I would be confident enough to use a battery with a swollen cell.

Did the video explain why it had swollen?

The pressure is in the respective cells. The valve is at the top of each cell. You get a click and hiss if there is a pressure problem, I had read that if there is a pressure issue on cell (common with overworking them) it stops the battery working until it's released.

I thought what a load of cobblers, but I tried it and it worked for me. Mine didn't look swollen, so maybe the OP has different issue.

 

[aveatry]

I had a DW battery 4ah that was over worked and wouldn't charge or illuminate the led.

I took it apart and used a very small flat blade screwdriver to press the top of each battery call... second to the last battery there was a hiss and presumably some pressure released (saw it on YT) reassembled and all has been well with battery in terms of usage and charging.

The pressure is in the respective cells. The valve is at the top of each cell. You get a click and hiss if there is a pressure problem, I had read that if there is a pressure issue on cell (common with overworking them) it stops the battery working until it's released.

I thought what a load of cobblers, but I tried it and it worked for me. Mine didn't look swollen, so maybe the OP has different issue.

Ok thanks I have taken it apart and can not find any kind of valve, tried pushing down with a screwdriver but just ended up slipping and stabbing the work top

 

[Harry Bloomfield]

Ok thanks I have taken it apart and can not find any kind of valve, tried pushing down with a screwdriver but just ended up slipping and stabbing the work top

Those cells, are 18650's, a standard cell, and cheaply replaceable, if you are so minded. There is no valve that I am aware of, simply a design weakness in the case, to allow the case to burst under pressure - rather than explode.

 

[aveatry]

Those cells, are 18650's, a standard cell, and cheaply replaceable, if you are so minded. There is no valve that I am aware of, simply a design weakness in the case, to allow the case to burst under pressure - rather than explode.

Thanks
I like to try and fix things but there comes a point where it involves so much work that its not worthwhile to do
I was hoping for a magic hissing valve but could not find one - and now I have a stab mark in my work top

 

[Harry Bloomfield]

Thanks
I like to try and fix things but there comes a point where it involves so much work that its not worthwhile to do
I was hoping for a magic hissing valve but could not find one - and now I have a stab mark in my work top

Whilst you have it in bits, check the voltage, across each cell. They should show 3.7 to 4.3 -ish.

 

[aveatry]

Whilst you have it in bits, check the voltage, across each cell. They should show 3.7 to 4.3 -ish.

How will that work when they are all wired together - looks like a little spot weld

 

[Harry Bloomfield]

How will that work when they are all wired together - looks like a little spot weld

They are wired together, in series, to give to 20v. You can still check the voltage without disconnecting anything, putting your probes across the top and base of each cell in turn.