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Cordless Drill Battery

03/14/2008 7:33 AM

This weekend I noticed my 18V cordless drill's battery was no longer able to take a charge. When I started pricing new batteries I discovered that they cost between $75-$90. I noticed that the battery has five screws on the top of the pack holding it together. When I removed the screws I was able to access the linked cells that make up the pack. The battery is comprised of 12 sub c cells, soldered in series. I searched online and found sub c cells ranging from 1900Mah - 5000Mah. The stock batteries are 1900MAh NICad cells. I ordered 12, 5000MAh NiMh cells, with solder tabs to replace the failed NiCad cells. It appears to be a straight forward transplant, easily accomplished in 20 minutes with a soldering iron. My question is, will my stock charger, rated at 2.8 amps, up to the task of charging the higher capacity pack? I bought several more dead cells on Ebay, and I want to replace the cells in all of the packs with the higher capacity cells. I am considering buying a "smart" charger, and recharging the new modified packs using alligator clips instead of the factory charger. I realize the new batteries will weigh much more than the old ones, and it would stand to reason that the newly modified battery packs should take much longer to charge. Is there anything else I'm not thinking of?

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#1

Re: Cordless Drill Battery

03/14/2008 8:08 AM

Ha, excellent well done that man.

I'd say the charger should be fine as long as the number of cells (e.g. The voltage is still the same) It will presumably just take longer to charge the higher capacity pack.

I should really do the same with my cordless driver as I havn't used it for a while and it's dead as a Dodo. that's the prob wiith these things. Maybe you've inspired me...once I've had a nap.

Del

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#2

Re: Cordless Drill Battery

03/14/2008 8:45 AM

What about the physical size of the replacement cells? Will they fit in the old case?

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#3
In reply to #2

Re: Cordless Drill Battery

03/14/2008 8:49 AM

All sub c cells are the same physical size. The only difference is their weight, the higher the Mah rating the heavier the cell.

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#4
In reply to #3

Re: Cordless Drill Battery

03/14/2008 9:00 AM

Yup in a perfect world that is true. However, I have NiMH cells from several manufacturers, Panasonic being one of them, whose dimensions are just a little off enough so that some of them will fit in one device but will not fit in another device while cells from a different manufacturer will fit.

Lets hope it will not be an issue for you. Is there any clearence in the case as it was configured?

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#5

Re: Cordless Drill Battery

03/14/2008 10:53 PM

How much did the new cells cost you?

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#6

Re: Cordless Drill Battery

03/15/2008 5:20 AM

I got 12 years our of a Makita battery drill which cost me ~$100 in 1995. It had 2 sets of batteries. I figured that when the batteries would not take charge any more, I could purchase one set of batteries for $69 or a new drill with 2 sets of batteries for $160. I bought the new drill and soldered some leads and battery clips on the old drill and keep it in the car, just in case.

The old drill must have conservatively put in more than 5000 wood screws which cost ~5c each and the cost to put them on 2c each. The old drill owes me nothing.

I am sure that if I tried a bodgie set of batteries, by the time I got them to work the cost would exceed both the new drill or the new proper batteries

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#15
In reply to #6

Re: Cordless Drill Battery

03/15/2008 12:27 PM

What was the rating on your Makita...I don't recall a 12v model, but maybe.

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#7

Re: Cordless Drill Battery

03/15/2008 8:33 AM

Before replacing your battery see if the charger has been blown. Electric spikes blow chargers all the time. The transformers in the chargers blow with small eletric spike it seems.

I take out transformers from all kinds of electric equipment to keep my drills and other batteries charging.

Keep you charger plugged into a surge protector and you won't lose so many chargers.

Everything at my home now runs thru surge protectors and I have not lost any equipment in years.

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#8

Re: Cordless Drill Battery

03/15/2008 8:41 AM

Hello,

I have a lot of battery pack who doesnt keep charge.

Can i have the place where you buy the replacement cells ?

regards,

Normand

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#9
In reply to #8

Re: Cordless Drill Battery

03/15/2008 8:49 AM

almost any electronic parts store can get them.

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#10

Re: Cordless Drill Battery

03/15/2008 9:10 AM

In My line of work I've used quite afew different brands of cordless drills with the same problem You had. Personally I have found that buying a new drill rather then new batteries was more cost effective even if One buys a cheap drill.However I now have a ridgid 18 volt drill that My son bought Me for christmas and it comes with a lifetime guarantee for the batteries and drill.

oilcan13

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#11
In reply to #10

Re: Cordless Drill Battery

03/15/2008 10:02 AM

lifetime guarantee for the batteries and drill.

Yeh, when the thing fails, they send the boys round to kill you

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#12

Re: Cordless Drill Battery

03/15/2008 10:20 AM

Dear Mad-Scientist & All,

Very cool of you to have repaired your batteries. I have learned a few things from the thread. I have also been taking some note of the Rigid brand tools and a lifetime guarantee implies that their charger is a smart type, instead of the type that simply senses temperature for charging. The advice concerning the consistent and uniform employment of surge protection is good as well. Thanks for sharing the results of your experiment. P.S. I do suspect a smart charger would be better, but in the world there is perfect and good enough.

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#13

Re: Cordless Drill Battery

03/15/2008 11:25 AM

I'd be interested to know whether you checked the individual cells. I have a (supposedly) smart charger for the 4 AA cells in my digital camera, (and others). This charger controls each cell separately, with 4 LEDs that go off when the corresponding cell is charged. I have noticed that even using a set of cells purchased as a set (same brand, same rating, presumably same production batch), that there is a significant difference in charging time for different cells. Even though the cells are never used except as a set of 4 in that same camera, over multiple recharges the charge time differential increases.

With a set of 12 cells connected permanently in series, sooner or later at least one of those weaker cells is going to be reverse charged by the current from the others during use. It is probably not practical to remove the cells from the battery and charge them individually, but I bet it would make them last longer.

Comments, anyone?

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#14
In reply to #13

Re: Cordless Drill Battery

03/15/2008 12:18 PM

A question - have you marked those cells so you can tell if it's the same one(s) each time that take longer to charge up? I'd be interested to know how long the hinkey ones last compared to the sound ones.

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#18
In reply to #14

Re: Cordless Drill Battery

03/15/2008 5:59 PM

Excellent Suggestion! No I haven't, but I will the next time I charge them. I do commonly write installation dates (or first installation dates for rechargables) on cells, but I have never numbered the set.

I have assumed (always dangerous) that the poor ones got worse, but now that you have suggested it, I'll find out. It'll take a while, as I don't use the camera that often, and it will take at least two rechargings of the same set before I will know. I think the camera is the only place I consistently use the same two sets (4 in the camera and 4 ready for replacement), so I know all 4 cells of each set have the same drain.

The other limitation is that there is no timer on the charger - I just have to watch the LEDs, and the probability of my being there and watching when each LED goes out approaches nil, but I'll try

Dick

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#16

Re: Cordless Drill Battery

03/15/2008 1:26 PM

I'll share a nicad trick.

install batteries in drill tape the trigger "on"

Put the whole thing in the freezer overnight.

the process seems to wipe out the charge memory & seems to allow the batteries to accecpt more of a charge.

Making sure to fully discharge & only using fully charged batteries will extend their lives.

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#19
In reply to #16

Re: Cordless Drill Battery

03/15/2008 6:02 PM

Have you tried that with NiMH or Lithium rechargables?

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#21
In reply to #19

Re: Cordless Drill Battery

03/16/2008 3:12 AM

If I could only figure out how to keep the camera taking pics in the freezer?

a quick search of nicad dischargers, shows they can be used nimh, but I don't see any mention of memory & nimh, just a suggestion to discharge before long term storage.

I'll close with a pic of some guys who could probably use some batteries & a few more brain cells

not an osha approved activity

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#22
In reply to #21

Re: Cordless Drill Battery

03/16/2008 12:27 PM

a quick search of nicad dischargers I presume you meant chargers!

My experience with Nimh indicates no need to discharge - they do it by themselves! (I am only being a little facetious here...)

I have a very nice small Makita NiCd drill that is (gosh - I didn't realize!) about 12 years old. Its batteries are obviously less than full capacity now, so a little over a year ago (or was it two?), I went to buy some new ones. They didn't have any in stock, but they did have a sale on a similar model with 2 Nimh battery packs, at less cost than the two replacement NiCd packs, so of course I bought the new one. The Nimh packs do last longer (drill more holes) than the NiCds when just charged, but I commonly go a month without using the drill (I have both a drill press and a mill). Of course I charged the batteries a month ago. When I go to use them, the new drill will maybe drill one hole, while the old one will drill several, so I end up using the old one more than the new one, unless I have enough work to do to justify waiting for the new ones to charge...

The Nimh batteries do seem to have less of a problem with 'memory', so it's OK to recharge them without totally discharging them, but the self-discharge rate is very disappointing.

just a suggestion to discharge before long term storage. What is considered long term? To me, that would mean maybe 6 months or more...

Dick

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#23
In reply to #22

Re: Cordless Drill Battery

03/16/2008 2:05 PM

Personally I avoid cordless things. as long as I pay the PG&E bill, my 20 year old milwaukee corded drill, always works!

No I meant discharge http://www.avtechmodels.com/discharger.html

Used by the RC crowd to keep their batteries in prime condition.

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#26
In reply to #23

Re: Cordless Drill Battery

03/17/2008 10:41 AM

Yes, I have a 40-something year old GE drill/sander/set that still works fine too. But is is sooo convenient not to have to have a plug or extension cord...

OK - now I understand. Do you know if they use the dischargers with Nimh? Interesting that your link was to New Zealand!

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#28
In reply to #21

Re: Cordless Drill Battery

03/17/2008 3:41 PM

Photographic evidence that the lifeguard is NOT on duty at the gene pool, either...

Guess you could set the timer on the camera and tape the switch so it would take a time-lapse series. Document whether the little light stays on or not...

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#29
In reply to #28

Re: Cordless Drill Battery

03/17/2008 4:50 PM

Are you following me?

I seem to bump into you everywhere.

I nearly posted this next 1 but thought you might get the wrong idea.

from a series wondering wether china is ready for the olympics?

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#33
In reply to #29

Re: Cordless Drill Battery

03/18/2008 4:45 PM

Maybe - they seem to have the long lines well thought out...

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#30
In reply to #28

Re: Cordless Drill Battery

03/17/2008 5:32 PM

Since you brought it to my attention, I took a look - I have a Canon S21S digital camera, which has a lot of features, but so far as I can see, time lapse isn't one of them. It sure wouldn't take much to add that feature. It does have two modes of 'Continuous Shooting', at 1.5 or 2.4 frames per second, but no means of engthening the time between shots. I'll have to look for that the next time I get a new camera (which isn't currently on the horizon).

Later I'll take a look to see if my video camera can do anything like that - its not handy right now.

Dick

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#34
In reply to #30

Re: Cordless Drill Battery

03/18/2008 4:51 PM

Concur, I don't see how it could take much. What's the significance between 1.5 frames/second and 1 frame/5 minutes? Same kind of logic circuit, right?

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#17

Re: Cordless Drill Battery

03/15/2008 4:05 PM

Dear MadScientist:

When charging your batteries-just make sure you have a charger that will automaticly turn off when the batteries are fully charged. Keep the charging alligator clips away from children.

As to increasing the rated amps with larger batteries-your drill motor is designed for the original rated amps-you may burn your drill motor out due to excessive heat by supplying more amps than rated.

Regarding "Cordless Smart Chargers"-most are protected by an inline fuse-when the charger stops working due to a spike-you can replace the inline fuse and go back to charging.

Mr. HandyMan

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#20

Re: Cordless Drill Battery

03/15/2008 7:36 PM

Mr. Handyman,

You don't supply amperage. Current flow (rated in amperes)

is determined by the voltage and the resistence of a circuit.

See Ohms Law.

Batteries of greater current capacity simply mean they will produce more work on the way to discharging.

That is an interesting point...varying capacity in cells of the same size. Who would have thought??

j.

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#24

Re: Cordless Drill Battery

03/17/2008 4:02 AM

I have a similar problem with my drill machine. Also 18v, but in this case, when i put it in the charger, the chargers light stays green, as if it is fully charged, but the battery is flat. So the charger thinks it is charged. How can i do something about it? I love the drill machine and thought of bypassing the battery completely (wire power directly - 18V of course). This will not be cordless though but at least i can use it still. Now it doesnt mean anything to me.

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#25
In reply to #24

Re: Cordless Drill Battery

03/17/2008 7:46 AM

It sounds like your batteries are being shorted out internally from cadmium dendrites. I have heard of people building battery zappers that they use to vaporize the small whiskers that form in NiCad cells. I have also heard of people zapping batteries with a welder to remove the whiskers. http://www.instructables.com/id/Revive-Nicad-Batteries-by-Zapping-with-a-Welder

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#27
In reply to #24

Re: Cordless Drill Battery

03/17/2008 11:04 AM

I have found that if I try to recharge my batteries after heavy use that resulted in a warm to hot battery pack the light shows charged until it has cooled down.

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#31

Re: Cordless Drill Battery

03/17/2008 11:24 PM

Regards all !!!!!

[Question]

<< . The battery is comprised of 12 sub c cells, soldered in series... >>

<< ... I ordered 12... NiMh cells ... >>

12 NiMh cells' voltage = 12 x 1.2 = 14.4V 20% less than 18V

How it will run for more time ?

dkwarner in #13

<< Comments, anyone? >>

There is a difference in using Cells in series & an OEM Battery-Pack.

It was a standard practice in assembling Battery-Packs by renowned manufacturers to select lots of cells for comparative Life-span.

There was a stringent Test-Set-Up & Special safety circuits built-in packs not to run below a certain point; say 1.0V/cell.

eg a 12V battery [10 cells of 1.2v] will cut-off if voltage drops below 10V.

But even then there is a probabillity of discharging an individual cell to 0V & reverse-chahge.

Your idea

<< ... This charger controls each cell separately, ... >>

is an ideal one, but too-complicated & expesive for large batteries.

Financial effect may also be considered. May be implemented o-in Highly Sophisticated Jobs but not for home users.

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#32
In reply to #31

Re: Cordless Drill Battery

03/18/2008 7:05 AM

I realized after I posted that the 18volt battery pack was comprised of 15, not 12 cells, I ordered 24, I only have 9 left to do the second pack. I'll need another 3 to do the next pack. I do have good news however regarding the first pack I modified. The pack performs flawlessly so far, no drop in useable power after using it all day. In back to back tests with a stock battery, it lasts about 2.4 times longer between charges.

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#35
In reply to #32

Re: Cordless Drill Battery

03/18/2008 4:56 PM

Woo hoo for you!

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