Reviving NiCd batteries - sort of boaty

Cloven

Cloven

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I have cordless power tools with NiCd batteries, one of which is failing to hold its change. I have seen companies that offer info on how to revive these batteries (at a cost). Has anyone any idea how its done and more to the point does it work?
 
There are special chargers which massage a bit more life into them, but generally, all you can do is fully charge them, run them flat, fully charge them, run them flat and so on, a few times to see if that works.

Or buy new ones, as they usually charge 500 times before dying....IMHO
 
If they're knacked, they're generally knacked.

However, you could try cycling them which is exactly what the machine would do.

Charge them up, then discharge at not too large a load. i.e. run a drill not under load but just spinning. Do this in one go but don't faltten them completely.

Then charge as normal. Cahnces are it won't really fix the problem but it may improve things short term.
 
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There are special chargers which massage a bit more life into them, but generally, all you can do is fully charge them, run them flat, fully charge them, run them flat and so on, a few times to see if that works.


[/ QUOTE ] Probably advisable not to run completely flat. I suspect that any decent gadget for doing it will monitor the volts and stop the discharge as soon as they drop a bit. I periodically run my drill battery down using a bulb but try to stop as soon as it starts to dim.
 
A failure mode that can occur after over-discharging (keep on using the battery after one cell has gone flat) makes a cell completely short-circuit. This can be recovered by applying a high current (several amps) for a few seconds; the idea is to melt the crystals that form between the two electrodes.
It's a slightly dangerous activity - the cell can explode I believe - and it's usually only a short term recovery. But I've done it a few times without any dire consequences, and in some cases a useable battery has resulted.

Derek
 
Hi Dave I send my tired battery packs to Recell www re-cell.co.uk They replace the old cells and you get back what is in effect a new battery pack. I don't have an old invoice to hand,but they are about half the cost of a new battery pack.
 
When our laptop batteries crap out- we stickem in the freezer overnite.... freezem solid, then thaw out and recharge.
For some reason this seems to get them working again..
Dont know it these are nicads or what, but worth a try!

/forums/images/graemlins/smile.gif
 
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I always understood that nicad batteries lost thier memor if not fully discharged.

[/ QUOTE ] The "memory effect" If you recharge them when only partly discharged they are said to "remember" that and then only give you that much capacity. That's why chargers and other equipment sometimes have the facility to discharge before recharging.

NiMH batteries are said to be less prone to this effect.

There seems to be some debate about it and not universal agreement about either.
 
Many thanks for all the replies.

Jamesmar - Thanks for the link. Sounds like it might be worth trying Re-cell as the cost of replacements is about the cost of a new drill!!
 
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I went out and bought a new drill + 3 batteries + free tools for the price of a new battery /forums/images/graemlins/confused.gif

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Exactly. Looking at the recell prices, strikes me its better to go along to aldi and buy a whole new set up for £20. wont last half as long as a bosch, but then its a quarter of the price.
 
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wont last half as long as a bosch

[/ QUOTE ] Provided you dont use them one from Ldil's or Adlis will last forever but if you actually want to use it a Bosch will be the better buy by far.
 
Got a quote for new Ryobi 12v battery from recognised supplier £38 inc vat. Just had a look at your link for Re-cell..... £37..... they claim to save you 50%?????
Bought a brand new 12v hammer drill/driver + charger + 2 batts sealed in box ebay £25.99 + £6 p&p ( Screwfix £79.99)
 
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