Rejuvenating drill batteries

[PTvor]

If you're having to flash a battery, it's on it's last legs. Some life from it will only be temporary, and it's capacity will be lower.

Having looked into it a bit that's my view. Nicads fail because of whisker growth and separator failure, and both are age and temperature related, and probably related to the original quality. If you zap them you are only going to break the whiskers which have bridged the electrodes, not the ones which are growing. Zapping isn't going to fix the separator.

Another thing which damages them and reduces their capacity is reverse polarity. This happens when you have a lot of nicads connected together, as in a drill battery, and you flatten it. There'll always be a weakest cell and it flattens first, then the others drive it backwards and damage it.

There are lots of Youtube videos on rejuvenating power tool batteries, but as I say, I don't have much faith that any of it has anything but a short term effect.

 

[brightspark]

Having looked into it a bit that's my view. Nicads fail because of whisker growth and separator failure, and both are age and temperature related, and probably related to the original quality. If you zap them you are only going to break the whiskers which have bridged the electrodes, not the ones which are growing. Zapping isn't going to fix the separator.

Another thing which damages them and reduces their capacity is reverse polarity. This happens when you have a lot of nicads connected together, as in a drill battery, and you flatten it. There'll always be a weakest cell and it flattens first, then the others drive it backwards and damage it.

There are lots of Youtube videos on rejuvenating power tool batteries, but as I say, I don't have much faith that any of it has anything but a short term effect.

your only prolonging the inevetable

 

[Wozzaaah]

Well, my hot water trick seems to have revived 10 dead AA's so I'm happy.

 

[steviec_lj]

I've got 130amps to play with at home, can't be ****'d taking myself down to the lock-up to do it with more. So touch wood it'll work. Will try it out tomorrow!

 

[normspanners]

Whiskers??? Are they made from small kittens. ??

You are stupid, you now nuffin, the cheap cells are actually made from cat FOOD.

 

[dannyp]

the arc welder occasionaly gets used to kick duff batteries into touch

 

[Bsmith]

Zapped a 18v Makita nicad when it failed to charge on charger, it works ok while it holds the mig charge, still won't charge with charger.

As I said before my battery appears to work ok for a while after a few mig zaps, but is there any danger in over zapping, like the battery exploding please, anyone know? I did buy a new battery but it's good having 2 charged ready for doing a job.

 

[chunkolini]

Norm, you caught me out then.
I was thinking 'internet grumpiness here' but no a simple fact.
Does this work on NiMh batteries?

 

[shenion]

but is there any danger in over zapping, like the battery exploding please, anyone know?

I see people saying "zapped for 15 seconds" and I just cringe.

We used to zap them yeas ago using a charged capacitor. That is a high current for a few thousandths of a second. That was all that was needed; any more and you are just boiling the batt and it can leak or explode.

 

[DrNik]

I was giving a battery 3 lots of 10 seconds bursts

 

[ibrooks]

Be VERY careful folks. The customer here uses some LiIon batteries for some kit here at work and we've had the safety briefings on them. If you mistreat these things they are not averse to giving back all of the energy stored in them in one lump. Now before you think yeah-yeah safety briefings equals scaremongering it has happened here more than once when people haven't been paying attention. No injuries yet but on the "best" one the net result was a new PC needed for the test equipment - the heatsinks dribbled out of the bottom of the case and the motherboard looked like it had seen the business end of a flamethrower up close.

Iain