# Cordless Drill Batteries



## Yoyizit (Jul 11, 2008)

MrBill_DIY said:


> the rechargeable battery won't hold a charge anymore for more than a few minutes


If it's Nicad there are ways to rejuvenate it that are detailed in electronic hobbyist magazines. You may need a current-limited lab power supply to do it. Another method charged up a capacitor and discharged it into the battery.



MrBill_DIY said:


> Is it normal for cordless drill batteries to kick the bucket after two or three years of light use?


The batteries in these applications are charged and discharged very fast so they meet performance goals set by the manu's marketing people. 
I'd say the batteries are being abused, and this is by design. And I guess in our throwaway society, that's fine [as long as the batteries don't explode].


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## Bondo (Dec 8, 2007)

Ayuh,.....

I've got a set of Milwaukee cordless tools,....
About 3 years, maybe 4,+ the batteries are Junk,....
Last winter, I made out like a Bandit with that Milwaukee Battery Recall,....
It got me 8 Brand New Batteries,...
Btw,... That's at $80.00 a pop,... New list price.... ebay is about 1/2 that...


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## HarryB (Dec 16, 2008)

*Re-building Drill Batteries*

Has anyone here sent their old drill batteries out to be rebuilt ?

I would like to know because I'm considering doing it for an old Sears 9.6v that I kept, which had more power and life than the two 14.4's [last a Ryobi] I've had since. This 'little' 9.6v was obsoleted by planning & design, the battery shape long gone from shelves.

I took one of them apart to see what was involved in the rebuild, but, before checking on the net, I assumed that the individual cells from which these are made were not available to consumers and tossed it. There's not much to it [with the old ni-cads] but unless you have the tools and skill to solder them properly, forget it. Also, I'm not talking about the lithium-ion type, which are dangerous to play with unless you know about controller chips. 

Anyhow, this old 9.6 with its two batteries was the perfect home drill, as it would go all day on these two doing framing work, and it was a lot easier to handle all day than these 18v monsters. From a productivity standpoint, it's worth the rebuild cost , but I need another battery, and they ain't making 'em. 
IS THERE ANOTHER PACK RAT OUT THERE HANGING ON TO ONE OF THESE ?
Obviously there is, but whether they see this post is the factor.


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## Termite (Apr 13, 2008)

Battery specialty retailers often will rebuild batteries. I think "Batteries Plus" is one such store. Check the phone book and I bet you'll find someone in your area that will rebuild the battery for less than the cost of a new one.

The aforementioned advice of home recharging using capacitors and such is not a good idea, is not all that safe, and shouldn't be considered an option.


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## Nestor_Kelebay (Jun 17, 2008)

Harry:

You should be able to get a 9.6 volt battery pack on eBay cheap.

I have a Porter Cable 12 volt MagnaQuench drill, and have never purchased a new battery pack for it. I kept having the old one rebuilt.

Just look in your yellow pages phone directory under "Batteries" and you'll find that about a third of the places that sell batteries in your area also rebuild battery packs.

I can't speak highly enough about rebuilt battery packs. A good battery rebuilding shop won't solder anything. They'll have a small hobby welder and will spot weld steel strips to the batteries to connect them all in series.

You will be given the option of having higher capacity batteries put in. ALL the batteries will be 1.2 volts, but they come in different milliamphour (mAh) ratings. For example, your drill will run twice as long with 2400 mAh batteries in it than it would with all 1200 mAh batteries in it. There is a difference in cost for the higher rated cells, but it's a small difference of only a quarter or 30 cents per cell.

The cost of rebuilding your battery packs with high mAh rated batteries will typically be about half the cost of buying a new battery pack, or lower.

Here's an insane example: I have Maytag "Computer Trac" coin operated washers and dryers in my building; three of each. These machines have a rechargeable battery in them that powers the circuit board so that it remembers how it's been programmed even when the machines are unplugged. I could tell that the battery packs were starting to go because when I would unplug a washer or dryer, then it would revert to it's factory set price rather than use the price I had programmed into it. I contacted Midland Maytag to find out how much these batteries cost to replace, and was quoted a price of about $100 each. So, new program memory batteries for all my machines would cost me $600.

I took a sample battery pack down to Prairie Battery here in Winnipeg and had new battery packs made up for $12 each, and they've worked flawlessly in my laundry machines for about 7 or 8 years now since I had them made.

If you can't find any place that rebuilds battery packs locally, you can find plenty of places online that do it.

PS: If you notice, rechargeable battery packs for cordless tools will always come in multiples of 1.2 volts. That's because they all use the same size and style of cells. So, they started with the 7.2 volt batteries that used 6 cells, then the 9.6 volt batteries with 8 cells, the 12 volt tools that used 10 cells, 14.4 volt with 12 cells and 18 volt with 15 cells. The cells are all the same, it's just that the higher voltage tools use more of them connected in series to produce larger voltages.


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## micromind (Mar 9, 2008)

Here's the lowdown on the capacitor thing with batteries;

Ni-cad batteries will self-discharge from full charge to no charge in about a month or so. When a ni-cad battery is discharged it has a tendency to grow 'fingers' inside the cell. These 'fingers' are conductive, and will short out the cell. 

The best, easiest way to get rid of the conductive 'fingers' is to hit the cell with a huge amount of current for a very short time. The 'fingers' are pretty small, and will be vaporized by the high current. A capacitor of almost any size will discharge before it can hurt the rest of the ni-cad cell. 

If a ni-cad cell is charged continuously at too high current for too long, it'll overheat and likely explode. Not a particularly big bang, but the chemicals inside are sprayed out in every direction, and would certainly be attracted to eyes! Even a huge capacitor doesn't hold enough of a charge to overheat a battery. 

I've 'rescued' a number of defective ni-cad batteries using a capacitor. Just be ready for a nice 'SNAP' when the capacitor pours several hundred amps into the battery for a few milliseconds!

Rob


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## HarryB (Dec 16, 2008)

*Thanks for the good grit.*



Nestor_Kelebay said:


> Harry:
> 
> 1. You should be able to get a 9.6 volt battery pack on eBay cheap.
> 
> ...


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## HarryB (Dec 16, 2008)

*Interesting . . . further elucidation pls . . .*



micromind said:


> The best, easiest way to get rid of the conductive 'fingers' is to hit the cell with a huge amount of current for a very short time. The 'fingers' are pretty small, and will be vaporized by the high current. A capacitor of almost any size will discharge before it can hurt the rest of the ni-cad cell. . . . . . . . .
> 
> I've 'rescued' a number of defective ni-cad batteries using a capacitor. Just be ready for a nice 'SNAP' when the capacitor pours several hundred amps into the battery for a few milliseconds!
> 
> Rob


 
Rob
Sure would be interesting to know your technique with this capacitor thing . . . . 

B.rgds,
hb


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## brokenknee (Dec 13, 2008)

"Zapping" battery packs is only a temporary fix. The "fingers" will grow back. I do not recommend it.

Battery pack life depends on how well the battery pack has been treated. Ncd batteries can be recharged any where between 500 and 1,000 times. Nimh can be recharged 300 to 500 times The expected life of a Ncd battery is approximately four to five years, (although I have heard of longer) Nimh have an approximate life of two to four years. Both have a high self discharge rate (loses charge sitting on the self). Ncd has a higher discharge rate than Nimh.

You should charge your battery packs before they get down to 1 volt per cell. (12 volt battery pack 10 cells, 1.2 volts per cell). If you do not, you run the risk of reverse polarity happening to the weakest cell. This will ruin your pack. A good rule of thumb is to charge your packs at least once every 3 months or so. Not doing so will almost guarantee an early demise for your pack.

Recharge your pack as soon as it shows signs of discharge for the same reason stated above.

Ncd can take more abuse than Nimh (discharged closer to the 1 volt per cell) but they also suffer more from the "memory" effect; this is why it is good to run the Ncds down close to the one volt per cell once every three months or so. 

Nimh does not suffer to the same degree as Ncd from "memory" effect but it does have some. Nimh are also available in higher capacities than the Ncd batteries and are more environmentally freindly.

For those of you that are considering rebuilding your own packs. I say go ahead and do it. It is not hard, anyone with basic soldering skills can do it. Just make sure you have a good hot iron, a 40 watt would work fine. You do not want to keep the iron on the battery more than two or three seconds or you will be transferring to much heat to the battery itself. 

Almost all Ncd and Nimh battery packs use sub c batteries; these can be ordered online at a few different sources. If doing so, order the ones with the solder tabs already spot welded on. This makes the job easier. 

You will most likly not be able to purchase them locally, I tried and was almost thrown out of one national chain store I will not mention. He accused me of trying to go into competition with him. I tried to explain I only rebuild for myself and friends, but he was still a jerk. I will not go there again.

I do have more to say, but this post is getting really, really long. If anyone has any questions, I will be happy to try to answer them; just post and I will reply.

Maybe we can talk about lithium Ion next time.


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## brokenknee (Dec 13, 2008)

Here are some more resources for those interested; http://www.batteryuniversity.com/

This one is a "how to" build packs http://www.batterieswholesale.com/battery_tips/assembling.htm


Sources for batteries, I have used both, both have delivered as promised. I do not have any affiliation with either site. "Moderator remove if not appropriate"

http://www.batteryspace.com/index.asp?PageAction=VIEWCATS&Category=296

http://www.batteryjunction.com/nimh-specialty.html


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## Erik Reppen (Jan 15, 2009)

Nicad is junk. Always was junk. Always will be junk. It was understandably useful to contractors, of course, but the batteries are too much of a hassle to make the cordless factor an actual convenience in a home or shop environment. I had no interest in cordless until Lithium Ion. Although Panasonic's Nimh drills probably would have caught my eye if I'd been paying attention.

If you have to pay 3 times as much for lithium ion, it will ultimately end up being worth more for your trouble. It's still a good idea to recharge the batteries occasionally but if you left them at full they're not going to drain in a week and then permanently die on you or have their total capacity reduced permanently.

But really, if odds are good that a tool is going to be left idle for months at a time, you should probably consider sticking with a corded. Much better value and performance for the price, typically. I got a Milwauke holeshooter for about 110 bucks that might outlast me if I don't go out of my way to abuse it. How much will you have spent when you inevitably replace that Skil?

That said, I love my m12 subcompact. I can't believe how much torque I get out of the silly thing and the batteries have been dellivering so far.


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