Monday, July 23, 2018

Saving a DeWalt lithium battery

Something that's guaranteed to jerk my chain is going to grab a battery powered tool and finding out that not only does it need charging, but that the battery won't take a charge. Tools with lithium batteries are the absolute worst for "Hey, you've only charged the battery 5 times, but it won't charge now and you need to spend $50 for a new battery."

I didn't like that particular BS when I was working and now that I've retired, I really don't like it. I'm not a piggy bank for DeWalt or aftermarket battery manufacturers. While a number of my tools are corded, I'm like everyone else--I prefer to work without the cords. Especially when you only need to drill one hole, it's just a lot less hassle in you life.

A project I've been putting off, because I knew it wasn't going to be even a little fun, was replacing the throttle cable on our 4 wheeler. It had been allowed to sit for longer than it's a good idea to let such things sit, and the throttle cable had seized. A basic inspection a while back had shown that the thing was routed by way of Albuquerque to get from the handlebars and the throttle body, so I had let it wait until I had no more excuses. Well, I'm now fresh out, so it was time to deal with it.

After considerable disassembly, much speculation on the intelligence of the designers and engineers and some swearing, I determined it wasn't the cable, but something in the throttle body itself that was the problem. After backing off the cable adjuster, I could get things to move, but it felt very...sticky. Some research on the Intertubz brought to light that the throttle plate can get gummed up and cause the problem.



OK, off to the auto parts store for throttle body cleaner. After I got home, I disassembled even more of the 4 wheeler, and found out that a double-jointed monkey couldn't get to a point where he could peer down the opening into the throttle body. Consulting my handy shop manual (You don't think I went into this blind, do you?) on the process for removing the throttle body, I decided that a root canal performed with a jackhammer and hot tongs would be preferable. So I went to get my DeWalt inspection camera.

An inspection camera is one of those tools you don't need a lot, but when you need it there is no substitute. This one has saved my bacon several times since I bought it. I expected the battery to be in need of charge, because I couldn't guess when it was last used. Sure enough it was dead, and when I slapped it in the charger, rather than the blinking red light, I got...

Nothing. Nada. Zip. Well crap, this is the only thing I have out of all my DeWalt tools that uses a 12v lithium battery. After this one and a 20v lithium DeWalt drill, I've sworn off the things, and started buying NiMh rebuild kits (and a couple of compatible DeWalt chargers) and rebuilding my old NiCad battery packs. The Li-ions are just too damn picky--especially if you work them hard and they are discharging fast. They'll turn themselves off and refuse to run. Thanks, but no.

Now the swearing started in earnest. I tried an inspection mirror, but no joy. There is no way to get the angle needed to see down the throat of the throttle body. Nothing for it but to price a replacement on Amazon and wait two days for Prime to drop it on my doorstep.

After a mild case of sticker shock for the DeWalt-branded battery, and briefly considering the no-names, I had this hair-brained idea--Is there was some way to fix this dead battery, even temprorarily?

Once again, the Intertubz provideth:



Of course, my situation was different, but as Gunny Highway said, "Improvise, overcome, adapt." I took a 12v NiMh and jumpered it to the dead Li-ion and waited a bit. When the jumpers were warm to the touch, I figured that we had transferred enough juice to give it a try. Guess what?



The little sucker is sitting on my workbench now, charging it's little heart out. I suppose I'm going to have to develop a habit of charging batteries on a semi-regular basis. Bloody inconvenient.

Edit, 7/25/2018: Just for the sake of completeness, the ATV problem was indeed a sticking throttle plate. It took 2 hours of disassembly to get to it and 4 tiny spritzes of cleaner to cure the problem. I don't know whether to laugh or set the thing on fire. I'll probably laugh.

3 comments:

Alan said...

Dewalt Li-on batteries, if they get too low, the charger won't start the charging cycle. I saved a discharged 20V battery essentially the same way you did by putting on a home-made charger of mine to bring it up enough so the stock charger would recognize it.
Hint for future - /always/ remove the battery from the tool when it's not being used. These new ones won't self-discharge like the Ni-Cds, but you can still kill 'em if left connected.
Just for reference, I have a 12V system with same battery you have, the whole set is about 10 years old and still working with no problems

The Freeholder said...

Good stuff to know. I'll start pulling it off the camera in the future. I'll pass this along to Son--he inherited the 20v drill after I found it to be too frustrating to use. He's happy with it though. I suppose it's what you'e used to.

Robert said...

So, a dumb 12v battery will charge a dead 12v battery but a smart charger says "Oh, noes, dead battery! Better buy a new one!". Capitalism at its worst, er, normal.