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Ni-Cad batteries

a.palfreyman

pfm Member
My Dewalt 18V drill batteries are getting tired. About 3yrs ago I opened them up to find 2-3 duff cells in each of the two packs. I recharged these low cells separately using a current limited psu and cycled the packs a couple of times which improved things, but fear they are as bad now if not worse.
Just spotted this:
https://itstillruns.com/refurbish-18v-dewalt-battery-6225112.html
This suggests that a 3 second burst from a 12V car battery charger can revive poor cells. Seems a bit risky to me, but I'm tempted as I have nothing to loose. Oh, I'd not remove the cells. I'd just 'burst' charge them in-situ. Any thoughts?
 
I can't see it making much difference. You would need to do it to individual cells also if going to try it.

When conductive "whiskers" form internally which can cause a cell to malfunction it was not unknown to try and cure this by getting a 10000uF or so smoothing cap and charging it to say 70V and then discharging across the cell to try and vaporise the whisker.
 
As mentioned in a previous thread
Scrap the NiCd cells and replace with Lipo cells
You will increase the capacity (Amp hours) considerably and you can charge them faster too
 
Aren't lipos a bit funny though? I'd read that these typically have a circuit which monitors charge/discharge rates to stop them catching fire...
 
I can't see it making much difference. You would need to do it to individual cells also if going to try it.

When conductive "whiskers" form internally which can cause a cell to malfunction it was not unknown to try and cure this by getting a 10000uF or so smoothing cap and charging it to say 70V and then discharging across the cell to try and vaporise the whisker.
This works if its the dendrite whiskers causing discharge. We used to freeze them overnight then give them very short (sub second) charges at upto 90A off a big power supply until the cell warmed up a bit. Your car battery will do similar. You are limping them on at best.

I have a similar DeWalt in the garage, I replaced it with a beast of a Hitachi drill, but I would like to make an adapter to to git the Hitachi packs to the dealt. There is a guy that does adapters for most packs onto ryobi cordless tools, so I'm sure you could make/3d print something for a dewalt.
 
Aren't lipos a bit funny though? I'd read that these typically have a circuit which monitors charge/discharge rates to stop them catching fire...
LiPo batteries are awesome, they just demand a bit more respect than nicads. Use a proper dedicated charger and they are fine. Most powertools just want to see the right number of volts to work. The Parksidebatteries for their stuff from Lidl is surprisingly good for the money.

Like this:
https://www.ebay.co.uk/itm/25554873...d=link&campid=5338728743&toolid=20001&mkevt=1
But someone may do one that takes a better value pack than dewalts.
 
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Lipo batteries are fine if treated with respect
as other's have said

It's easy enough to strip out and throw away the nicad batteries and replace them

Alternatively...if someone makes a converter for a Parkside or similar...then all the better
 
Thanks chaps,
I'll look into this.
Car battery charger has reinvigorated 1 cell. Just pressed the clips to ends of cell after removing most of card. 4 more cells from same pack no difference after about 6 pulses each. Unless I can couple some caps to give about 10mF and charge to 60V off my bench PSU as suggested by Jez...:confused:
 
Why bother mucking around with dying battery packs? You can make $50 or more an hour cutting lawns and then just buy a new one, and if you are handy enough to even attempt to restore an old battery pack then you could charge $100 an hour for misc handyman repairs/jobs for people who don't know how to (all cash work of course), then you can buy new Makita LXT tools/batteries and dump the Dewalt NiCd stuff.
 
Oh, and I should add that as a professional engineer (metallurgist) of over 30 years standing, I can only DREAM of $50 (£40) an hour...
 
I bought some cheap 12V makita ones of ebay and they work perfectly, I also have a couple of the 7.2V stick ones for my old 90deg drill again faultless.

Pete
 
Last time one of my old cordless drills had its battery die, a 14.4v nominal jobbie - instead I just soldered a cheap pair of c.15A croc leads to the battery terminals - about £6 then from amazon (and recycled the battery)

And now use it for odd jobs on the cars, clipped to the SLA terminals instead; good heavens does it develop a torque it was never capable of, off Nimh C-cells. & I don't care if this burns it out, I'll repeat with some other junkbox freebie likewise when it does!
 
When I did my decking I used my small blue Bosch mains drill for some screw a it had mountains of torque compared to my 12v makita drills, but the impact driver was easier to use much less strain on your wrist.


Pete
 


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