Battery Resurrection

[NightBandit]

Battery Gurus,

I have a battery question that isn't directly related to flashlights, but I hope that you guys can help me and that my thread doesn't get the boot.

The battery pack for my cordless drill (15.6v) is completely dead. I accidently left it out in my shed all winter long (shame on me) and now it won't take a charge at all. It reads 0.00 volts on my multimeter.

Does anyone know if there is a way to resurrect my battery pack and get it to take (and hold) a charge again?

Thank you,

NightBandit

 

[B@rt]

I think you will need to replace the cells....

 

[Curious_character]

The short answer is that the battery is a goner. You'll need to replace it.

The battery is probably NiCd. If the voltage stays at zero volts after a few minutes on the charger, it means that the cells have grown internal short circuits. This is a fairly common failure mode of NiCd cells. While there are methods to clear the shorts, when successful they result in cells with very fast self-discharge, and the shorts tend to re-form after a while.

c_c

 

[SilverFox]

Hello NightBandit,

Welcome to CPF.

It is very possible that your pack has bad cells in it, however, if you have some protective clothing and safety glasses, there are a few things you can try.

For the sake of this discussion, "Momentary" means about one half second.

The voltage of your battery pack is close to the voltage of a car battery. You can "jump" your battery pack to see if you can wake it up. This involves a MOMENTARY connection with your car battery.

There are some dangers to consider...

If the pack is shorted out, hooking it up to your car battery could be similar to dropping a wrench across the battery terminals. There could be a big flash that melts the car battery terminals, and if your car battery is weak, it could explode from the sudden load. It also could create "issues" with the cells in the tool battery pack.

This is remote, but if you try this you should be prepared. Have a bucket of water handy for washing and for fire suppression if needed. Wear protective clothing that you can rip off rapidly if needed. Wear safety glasses and a face shield if it is available. Finally, have someone standing by, at a safe distance, to call for help or render help if needed.

About 95% of the time, nothing bad happens, but I always feel it is better to understand what you are getting into before you are in the middle of it.

After your "momentary" jump, measure the voltage of the pack to see if it has moved off of 0 volts. You may need to do a few "momentary" contacts to register a voltage. Once you have a voltage reading, drop the pack into its charger and see if it will charge up.

If you go through several "momentary" jumps and still have 0 volts, contact Tom at Battery Pack Rebuilders and get a quote on what it would cost to replace the cells in your pack.

If you get your pack to charge back up, try it out. It should work normally, but may have a high self discharge rate. If it doesn't work well, you are back to having the pack replaced.

Tom

 

[aerosimon]

Hi SilverFox, Do you place the batteries in series? Also, what sort (if at all) of fuse capacity is enough to run in series to allow the battery to recieve a good dose, but not allow your car to fully pass 400 spectacular amps in short mode. This may improve safety. Is it true that nicads die closed circuit and nimh open? If so and the drill pack is nicad, can you simply pass try pass 1.5V through the cell and measure seeing if all cells are dead, although i do doubt they all go together...

Just wondering at this point, I wll probably be in this same position sometime soon.. Oh,, and may a jolt to a lead acid revive them from sulfation in the same manner?

thanks, and good luck,
aerosimon

 

[SilverFox]

Hello Aerosimon,

You would be placing the tool battery pack in parallel with the car battery. A fuse would be a good idea. A 10 - 20 amp one should do.

NiCd and NiMh cells die both open and shorted out.

A jolt may temporarily help a sulfated Lead Acid battery, but you would have to hook up 24 volts to do it. This is not recommended.

The best success I have had with sulfated Lead Acid batteries is to add 1 tablespoon of Epsom salt distributed evenly to all of the cells. You follow this with an overnight charge. Quite often it will recover. Every time I have done this, the recovered battery lasted for almost exactly 1 year. After that, it could not be recovered again.

The theory is that the Epsom salt dissolves some of the sulfated material to expose some of the electrodes to the electrolyte. I have no idea why it dies again in a year.

Tom

 

[uk_caver]

At the risk of stating the obvious, if the battery really reads 0.00V on a voltmeter, is it possible that there's just a broken connection inside?
If you put a 1.5V AA cell in series with your battery, do you get 1.5V on your meter, or still 0.00V?

Connections inside drill packs can sometimes just corrode through, and/or get broken from handling (either the tags snapping, or coming detached from a cell, possibly aided by corrosion underneath.
The packs on an otherwise excellent drill that gets used underground (where the packs get damp, and even with care, often somewhat bumped in transit) seem to develop open circuits on a fairly regular basis.

 

[SilverFox]

Hello Uk caver,

Ah, yes, the obvious...

Excellent suggestion.

Tom

 

[matrixshaman]

I have used a 10 amp or even 50 amp car battery charger in the past to do similar things with Nicads and have brought quite a few back to life this way. After their kickstart charge normally and you may get lucky. If you can disassemble the whole thing and check individual cells that's another consideration - jump start each one if needed and replace any bad ones that won't come back. When I do these tricks I wear protective glasses or welding helmet, heavy gloves and leather coat.

 

[bill_n_opus]

I'm thinking of order a 15.6v rebuild from batterypackrebuilders.com as Tom suggested ... I don't like the idea of trying to jumpstart my batts and all that stuff. Sounds dangerous!

 

[uk_caver]

It's at least worth making sure the problem isn't just an open circuit.

Is it possible to open the pack without too much damage?

 

[NightBandit]

Thanks guys for all the suggestions. I think that I'll check the connection, but I have a feeling that since both of my battery packs are dead (both wintered over in the shed), that it's not going to be that easy.

And as much fun as having my car battery blow up in my face sounds (even a small chance), I think that I'll pass on that (though if I can get my hands on a jump starting battery charger, I may try that). I think that I'll just break down and buy a new battery pack or two. Heck, maybe I'll just but a new drill, they're not that much more than a new battery pack these days.

Thanks for the help,

NightBandit

 

[aerosimon]

If both went together over winter, Id bet the jumpstart is a very possible fix. Very unlikely that both packs sitting idle had contacts break at the same time.. Modern tools are cheaper, but quality still costs.. Im no expert, but a smaller 12V battery like from a spotlight could be used more safely than car (if available),, much less CCA, non spillable, and no car out of action risk if you are worried.. good luck,

and thanks SilverFox

 

[Trashman]

Ok, here's my chance to get an answer without starting a new thread.....

Ok, say his battery pack worked, but after say, 20 charges, the run time dropped from 35 minutes (new) down to 10 minutes. Would it be possible to recondition the cells?

I ask this, because I use Sanyo 2500's w/30 minute charger in a 2.5" TV, and the batteries seem to have lost more than double the capacity with only 20 charges or less.

 

[65535]

Well charging above .5C causes cell degration, 2C charging shows more rapidly, you could try a forming charge of .1C and see if you can't get them full again, final idea is that you aren't getting fully charged cells.