I have an 18V drill (15 sub c cells), its charger trickle charges at 85mA with no termination, i plugged it in and forgot about it for 2 days, it was fully charged (21V) and a bit warm, i used it and after about a dozen screws its dead, the voltage reads 18.4V (50% charge roughly) but won’t power a screw into wood now. It has 15-20 cycles on it and i bought it a few months ago.
The instructions say don’t leave it on the charger for more then 30 days straight, i have never left one more then 12 hours but this one completely slipped my mind. It was at 40%ish when it was originally put on the charger
Will the battery recover if i charge it now, should i try to drain it further (it appears dead even if the voltage doesn’t agree)
What I have found with a lot of Ni-Cad packs, is that there is always at least 1 cell that depletes rather quickly. It’s only 1 out 15, so not much to notice when using it. I believe that once a cell is depleted and current is forced thru it, it “reverse” charges it and it dies. But 1 out of 15 is only 1.4V, so all seems well. Sometime in the future, another cell does the same thing, etc., etc.
The most common complaint I hear from contractors that switch over to Li-ion is that the tool just shuts off. It doesn’t “run down”, it just shuts off with no warning. WE know why that is, they don’t.
I believe that Ni-Cads are VERY sensitive to reverse charging, and the WORSE thing one can do to a NiCad pack is run it down so far that the tool doesn’t work. When that happens, there is probably at least 1 cell being reversed charged.
With so many of the packs that I mentioned above available in the bins, it should be rather easy to find one, or another lightly used pack that contains sub-C cells and replace any damaged cells yours may have.
I have found that by charging and discharging, repeating cycle three times, nicad battery run time can be improved. My hobby charger has this option. The other method is to use the sucky incandescent flashlight to drain completely. Then charge. Repeat three times. Nicad developed a memory and by using the above method can be rejuvenated to some extent. I too used new and recycle bin batteries to rebuild packs.
I have abandoned nicad for lithium and have obtained 75% of them from recycle bins. The secret to any battery powered tool is always have a spare battery!
very interesting, it has a warranty so i won’t try to fix it but i will try charging and draining it a few times and see if it comes back to life.
I never considered the single cell problem but that makes a lot of sense
I seem to measure my duraloops pretty accurately and reproducibly by voltage, but this power pack is a black and decker, the model number is HPB18 and i am going to use the warranty
Don’t do that if you value your pack. Read the posting above about reverse charging cells. It’s a fact of PACKS, not single cells.
It’s OK to completely discharge SINGLE CELLS………NOT packs.
I’m shocked with how many people have heard of the memory effect, people i know who can barely figure out how to work a VCR know about the memory effect.
It would be amusing if it wasn’t so annoying, right?
Warrantying this one sounds like a good idea. As flydriver said, pulling all the cells in the back to zero individually should be fine (resulting in an overall zero), but attempting to do that to the pack as a whole in one go will not improve things.
In fact I think that overcharging the pack a bunch might be better than putting several full cycle on it. Just leave it trickling until all cells have achieved a full charge (you won’t be able to measure them since you aren’t breaking the pack open, so just leave it for a long time).
In the end dchomak might be right, I have no idea how much damage a serious reverse charge does to a NiCad.
I seriously think not. Most likely they were either crap batteries to start with, there was bad solder joint in the pack, or some other issue. NiXX deals with trickle charge with essentially no issues at all……as long as it really is a trickle charge.
Its certainly possible its bad luck and/or coincidence, all i know is it worked fine, i put it on the charger, forgot for two days, pulled it out, tested voltage (was 21V), used it on a few screws, it stopped running i checked its voltage which says about half charged and its useless now.
