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Questions: Repowering Cordless NiMH Tools - Printable Version

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Questions: Repowering Cordless NiMH Tools - addo - 27-03-2013

I've a 15.6V Panasonic cordless driver drill of many years' service. It now suffers from aged batteries. I'd prefer to replace the cells than buy a new kit, as it potentially offers me a 50% saving to do it this way and I also want a new cordless rattle gun.

The battery packs are 13×Sub-C NiMH cells. I haven't noted the code on their paper jackets, so don't know their characteristics.

For a power tool with alleged "fast charge" (it used to charge these batteries in slightly under an hour from dead flat) what characteristics should I be looking for in battery specs?

I'm asking here because there seem to be a few crafty people when it comes to DC.

Thanks, Adam.


RE: Questions: Repowering Cordless NiMH Tools - crickleymal - 27-03-2013

I'd try to get something close to the original batteries. Seeing as Panasonic make or at least badge batteries, their's would be favourite. I have tried replacing them with AA batteries in the past but they just can't handle the current. The internal resistance is too hight and the voltage drops if you load the drill in any way. If you find a decent souorce let me know as I'm sure I'll have to do the same soon. The price manufacturers charge for replacement battery packs is ludicrous.


RE: Questions: Repowering Cordless NiMH Tools - addo - 27-03-2013

You're bang on about the replacement pack pricing. I just have no suitable knowledge of batteries and while there's no shortage of cells that fit, there's a wide range of characteristics and amperages.

I'd wager all the new batteries including Panasonic badged ones, come out of China - the question is which manufacturers or suppliers can be relied upon...


RE: Questions: Repowering Cordless NiMH Tools - evdama - 27-03-2013

I was given a new but faulty Dewalt 7v screwdriver (only turned out to be a dodgy connector in the trigger-easily fixed)
It had a 1.3ah battery which was useless-but the ebay 2ah one from china is still going strong 3yrs later -far superior.

I also inhereited my dads bosch 12v driver - the batteries are well shot but at £50 a pop I think the best place is in the bin.


This clip is a last resort..
Welder fix


RE: Questions: Repowering Cordless NiMH Tools - andy-womble - 27-03-2013

Bought a 12 volt cheapy drill from Aldi a few years back and the battery pack FUBARe'd on me. New battery pack potentially more than the drill was worth but too good just to throw out. Ended up doing a bit of open heart surgery and soldered two flying leads internally and making up a suitable flex and croc-clips. Now use it from the car battery as a drill and to wind the legs up on the caravan with suitable socket and 1/2" drive extension with end turned up in the lathe to fit drill chuck...


RE: Questions: Repowering Cordless NiMH Tools - shedpete - 27-03-2013

Hardly worth tackling as a DIY job in my view unless your time is worth a lot less than your money :-) and you like faffing around with a soldering iron - there are stacks of power tool battery re-celling places and they'll have access to the correct cells from trade suppliers and even (gasp) provide a warranty. I'd look for a local one but there are stacks online too e.g. (just first hit from Google):

http://www.recellyourbattery.com/power-tools


RE: Questions: Repowering Cordless NiMH Tools - evdama - 27-03-2013

(27-03-2013, 04:56 PM)shedpete Wrote:  Hardly worth tackling as a DIY job in my view unless your time is worth a lot less than your money :-) and you like faffing around with a soldering iron - there are stacks of power tool battery re-celling places and they'll have access to the correct cells from trade suppliers and even (gasp) provide a warranty. I'd look for a local one but there are stacks online too e.g. (just first hit from Google):

http://www.recellyourbattery.com/power-tools

Thats half the cost of a new mid-range drill!
Plus the cost of sending it.
Plus the drill will probably be well worn.
No -like it or not the throwaway culture will get to us all eventually.
Wait until the battery is completely Kaputt,try the mod-if it fails then youve lost nothing ,buy a new drill.


As I understand it Nicads have "memory" so you need to completely discharge before recharge.
My well battered Erbaur 24v battery is 5yrs old and still holds a couple of solid days work of charge-I think its because I do this rather than its quality


RE: Questions: Repowering Cordless NiMH Tools - addo - 27-03-2013

I paid $600 for this drill in 2001; they have obviously become better value in recent years. To buy a contemporary equivalent would be $500 with two new Li-ion batteries and charger.

I'm not someone who lives my whole life on the clock. Time such as I may spend on forums is also fixit time, and I'm happy waving a soldering iron about. That's why I reckon it's worth a crack.

From memory, we're not supposed to mail batteries here; it obstructs otherwise good options like the site linked to before.


RE: Questions: Repowering Cordless NiMH Tools - shedpete - 27-03-2013

What do you mean by 'the mod'? If he's buying new cells to DIY a repair that's a non trivial cost...

It is a close call between re-celling and just getting cheap replacement (copy) packs from Ebay... or as you say just wait for a special offer and get a new drill.

I've also done the flying leads thing along with a hefty DC power supply so as to have a 'corded' version for the shed.


RE: Questions: Repowering Cordless NiMH Tools - evdama - 27-03-2013

(27-03-2013, 06:05 PM)shedpete Wrote:  What do you mean by 'the mod'? If he's buying new cells to DIY a repair that's a non trivial cost...

It is a close call between re-celling and just getting cheap replacement (copy) packs from Ebay... or as you say just wait for a special offer and get a new drill.

I've also done the flying leads thing along with a hefty DC power supply so as to have a 'corded' version for the shed.

Mod- The welder thing in the link
Theres also a trick in the same batch of clips that sometimes works by simply flicking the charger on and off repeatedly for a few minutes