Battery pack repair for hand tools.

Started by Okie Bob, December 10, 2011, 09:36:54 AM

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Okie Bob

I use a lot of battery operated hand tools including a drill and skill saw. Mine are DeWalt 18V models and I like them a lot. Recently I learned that I don't need to go purchase a new battery pack when my old goes goes south on me. My old DeWalt drill battery pack died and I found out I couldn't even buy a replacement, it's obsolete. Initially, I figured to just go buy a new drill as the cost of the battery pack is almost the cost of a new drill. So, I got to thinking and did some looking on the internet about reparing my old dead pack and found out it is
not only possible but, much less cost than a replacement and pretty easy to do.
The batt pack is made up of 1.2V NiCad sub C cells connected in series. So an 18V pack has 15 1.2V cells. If you take your pack apart you can measure the voltage of each cell and determine which ones are bad. Typically only 4 or 5 are bad and can be changed out with a soldering iron and time. You can buy new cells for $2.50 each so four bad cells makes your total cost about $10.
Honestly, it's not really that simple and I learned a lot from my first attempt. But, I did it, it not only works, my drill lasts at least twice as long as it did when new and well worth the time and energy invested.
If anyone is interested, I can provide some places to get the cells and articles I found on how to actually go about it. Or you can google it for yourself.
One last thing. The cells provided by the manufacturer are normally pretty low in quality and capacity. At best they are 1200 mAH (milliAmpHour). The ones I got for my pack are 3000mAH and 2.5 times higher capactiy and therefore give much more run time between charges. You could also use NiMH or nickel metal hydrid cells or even lithium ion cells but, they are much more expensive..much more and may or may not work with your charger.  Lots to learn but, fun and I figured I saved maybe $100 doing it myself.
And that, my friends, is my story and I'm sticking to it!
Sooner Born-Sooner Bred-And when I die I'll be Sooner Dead

Don_P

Please post some details  [cool] I've got a couple of dead batteries floating around.



firefox

Bruce & Robbie
MVPA 23824

DirtyLittleSecret

Ive gone through a set of Ryobi, Milwaukie, and DeWalt.  Finally settled on Ridgid since the battery packs are also covered under the lifetime warranty.  Have only had to return one battery, but turn around time was only about two weeks.  Already paid for themselves, and Im sure they will continue to do so in the future.
Thumb, meet hammer...hammer, meet thumb...


Okie Bob

I'm copying an email I sent to another Country Plans user that has a few links and some comments I made to him.
Anything else, let me know, glad to help.

http://www.astromart.com/articles/article.asp?article_id=587



http://batterieswholesale.com/faq_nicad.htm#1



http://www.zbattery.com/Batteries/Sub-C



Bruce, always happy to help fellow CountryPlans buddies!

I would recommend the first thing you do if you want to rebuild a battery pack is to take it apart and find out how many cells you need to replace then start searching for the best deal on what you need. ZBattery seems to change their prices pretty regularly and if you buy at least 20 cells you save with most any supplier.

Be SURE you are getting the correct replacement. Their doesn't seem to be a standard for sub C size batteries.

I ordered some and they were too big, Had to order again after measuring the ones that came with my pack and making sure of the size ordered. I believe in all cases you probably need to order the ones with the tabs. If you decide you don't need them they can easily be removed. Another thing not noted in the article is that you can take a pair of needle nose pliers and gently remove the tabs from the bad cells, saving it for your replacement. If their are two adjacent bad cells you will need the tabs.. Be double sure you don't short out the cells as you try to solder them in place. I found that as soon as I remove the cells from the pack, wrap a couple of turns of black electrical tape to hold them in place. This will make reassembly much simpler. I made the mistake of not doing this on my first repair and ended up doing it twice as it would not fit back in the case the way I had it.

Just take your time and you'll do fine. And consider getting a complete set of cells with a high mAH rating if you are a heavy user...the typical 1200mAH cells work ok for most home applications. Just my experience.

Good luck and please let me know if this works for you.

Regards,

Okie Bob
Sooner Born-Sooner Bred-And when I die I'll be Sooner Dead

MountainDon

#6
We used to race 1/12 and 1/10 scale electric cars and I made up our own battery packs so that part comes easy. I had a devil of a time finding a tool bit to fit the screws that hold the Ryobi packs together though.

It's known as a security torx bit I believe; Torx star with a center pin.



Just because something has been done and has not failed, doesn't mean it is good design.

Okie Bob

Don, I bought a set of these security torque bits at my local auto parts store for under $10. Apparently they are becoming quite common and you have to have the bits to work on some car parts and I'm sure many other things.  It's the battery packs way of keeping you from getting to the cells and repairing your own battery packs, thus making them a lot of money by selling you a new pack vs cheap repair.
I learned this from my local hardware store when I was going to repair a battery pack for them but couldn't open it up. They didn't sell the security bits but, told me the parts store did. Problem solved.
Sooner Born-Sooner Bred-And when I die I'll be Sooner Dead