How about converting a NiCad cordless drill to Li-Ion

Batteries and Chargers Rechargeable Batteries
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Years ago I was heavily invested in the 7.2V Makita cordless drills. Remember this one?

But wait, that is NOT a Makita battery you say? Well it’s not! As many of us have witnessed, cordless drill batteries do not last forever. That’s been true for NiCad, NiMh and Li-Ion. I was amazed when one day I was in BJ Wholesale club and saw this flashlight for sale.

I noticed immediately that this rechargeable flashlight ran on its own Makita Battery pack clone. Those batteries were a perfect copy of the Makita! Made in Hong Kong. How could they get away with that, I asked myself. As you can probably guess, back then a replacement battery, as now, just cost too much. Made it hard to justify buying them. But this flashlight-battery combo was only $7.50! So I bought one and tested it out. The cell was not quite as good as an original Makita, but is better than some of my worn out ones. I went back for more but there were only 2 left. I bought those, and never saw any more of these anywhere else. I have had a number of those Makitas over the years, but eventually all of the batteries ran out. I lost one of the drills, ran over another with the snowblower. I have 2 left, one is a single speed that I do not care for, and the one above. I remember that it had some real power, it could snap 1/4’ lag bolts rather than go into a full stall. Wouldn’t it be interesting if I could convert the battery pack to Li-Ion?
Earlier this year I got a hold of 20 IMR’s courtesy of this post

These cells pack a punch and would be great for this mod. For now I will just do a proof of concept, hack something together quickly to see if it is feasable. Here is a bunch of pics of what I have.
The flashlights, useless now, but I will keep them for now. In the future, who knows? I do know this, that If I throw them out, later I will wish I didn’t!

The old chargers, useless now. notice I had a 12V car plugin. That was a hot setup back then!

My old, worn out cells.

Comparisons of the Makita pack and the clones



I stripped the cells out of 1 of each battery pack. First the cells from the Makita

Now the clone. How about that, Made in Japan!
All cells are sub C NiCad, no surprise here.

The tops of the 2 packs. The Makita is on the right and the clone is on the left. I decided to use the top terminals from the clone as they are soldered and easier to work with.

Now remember at this point I am just going after proof of concept. I will now soldier 2 IMR 18650’s together to see if it will work
Soldiering the cells to the top connectors

I plan on using 3/4 inch pipe to sleeve the cells. Here is one in place.

For the test I will connect 2 IMR’s in series for 8.4V. This drill should really perform at 8.4V, 1.2V more than stock.
I put the pack in the drill and made a short video of the drill performing as I suspected it would. I buried a 2 1/2” deck screw edgewise into my workbench!

More to come, I will have to install some over current protection and a way to charge the cells in the pack. I am planning on using 2 of these. One for each cell. I will have to charge each of the 2 cells individually.

http://www.ebay.com/itm/10pcs-Mini-USB-Lithium-Battery-Charging-Board-Battery-Charger-module-5V-1A-/370800719607?ssPageName=ADME:L:OU:US:3160
If anyone objects to a cordless drill mod on a flashlight forum, just remember that some of the parts are coming from a flashlight. Besides, I am planning on adding an LED to the trigger. Feel better about it now? :smiley:

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Link to USB charging boards?

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http://www.ebay.com/itm/10pcs-Mini-USB-Lithium-Battery-Charging-Board-Battery-Charger-module-5V-1A-/370800719607?ssPageName=ADME:L:OU:US:3160

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For every 3 NiCd cels use one Li cell.

Just find ones that fit.

But NiCd cells are tough. Li and NiMH cells aren't.

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nice job! Interesting use of the USB charger boards. I’ve used a ton of them (never seen them that cheap though!), but never thought to use them in >3.7V packs. However, why not use 1 board and a slider switch to switch between cells? It’s not like you’ll be able to charge both cells at the same time (or could you? My electronics knowledge is pretty miserable).

I’ve rebuilt a couple of NiCd packs with salvaged li-pos (I checked HD at the time you found your packs, but no cigar) and the difference is amazing (Something else to use salvaged cells in - powertool packs!). Either the same weight and 2-3X the capacity, or less than half the weight for the same capacity (or more). Plus they hold their charge way better, so you don’t have to remember to charge the batteries (usually on crappy NiCd dumb chargers) before use.

Might be worth rigging up a buzzer or something to protect against overdischarge, if IMRs need it.

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I like it! I have been thinking about doing the same thing with my Milwaukee cordless drill. The problem was charging. I’ll have to look into those usb boards.

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I want to do this with the panasonics for my 18v dewalt drill packs which are Nicd.

I while back befoe joining the forum and knowing the risks of explosive batteries I went on the bay and bought some YKS brand 1800mah 11.1v hooked them up in series and i would charge them with their independent challel chargers. I thougout I was a geneius the saws and drills would perform awesome. One day without warning a battery blew up while charing inside the house. Melted the housing and created a nasty smoky mess. Abandoned the project for a while. But now i think i will try it out again with these 18650 cells.

How do you get the solder to stick onto the shinny terminals on the battery. Everytime ive tried they break loose even when using flux.

By t h e way why do u charge them with those usb boards. You can get an adjustable constant current buck or boost driver and set it right and charge the pack in one shot.

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I don’t think you want to just charge several cells in series. Over time an imbalance will occur in the amount of charge each cell accepts. When cells are charged in series in power packs, sophisticated balancing circuits are in the charger that balance things out.
On my set up, I am working on having the 2-18650’s just slide out, like in a flashlight, so that I can charge them separately in a regular charger.
As it is now, I use 2 of those boards to charge each of 2 cells separately. They are balanced that way.

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Ohh I didnt know that I have charged 3 in series of the same mah rating with a constant current charger and it works. I use them on single cell flashlights.

I will look into this maybe im on the wrong track again.

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I know that, with the exception of LiFePO4, Li-Ion batteries don’t maintain a (more or less) constant voltage as they are discharged the way NiCads do. Would using IMR batteries NOT result in a drill that loses power as the batteries are drawn down, especially since a NiCad drill probably has no voltage regulation?

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I can’t say ill object to any mod whatsoever.

Nice work!

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soldering to terminals - scuff them up with a file or carefully with a dremel grinding wheel. Then tin terminals and wires separately.

power over discharge curve - although the packs I’ve built (5S, 18.5V nominal) discharge down to 15V I haven’t noticed any difference in power of the tools I’ve used them on over the discharge curve. Some of them (strimmer, hand vac) are pretty brutal on batteries, but they’ve all been fine. I had to use one of the old NiCd batteries a while back after a polyfuse tripped in one of my DIY li-ion packs and that was completely miserable - power was down and only got worse. At the end the strimmer was just gently brushing the grass :slight_smile:

If you’re going to use serial batteries and charge them as such, either get a hobby charger and balance charge them or a PCB with built in balance charger - imbalanced batteries will go boom eventually. If you’re skipping a PCB, then get a voltage monitor or alarm as you can very easily destroy li-ion batteries by overdischarge and depending on power draw/ battery configuration you can do that without even realising it.

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+1 I tend to lightly sand the terminals with a dremel before soldering. I also use extra flux and a 180 watt soldering gun. I haven’t tried it with anything less powerful although I’m sure it can be done… I like to be in and out of there in about two seconds.

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That’s right, you want to use a lot of heat for a very short time. Nothing wrong with that, contrary to what many will tell you. After all, when packs are made, during manufacturing they heat the terminals up so hot as to weld them to the cell. It’s called a spot weld. Extreme heat for an extremely short time. A big iron can do that, a small one can not. Using the small iron is what will get one in trouble.

If one does not know what they’re doing, they better not try.

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Nice thanks, I will try it. I have a hobby charger I can wire in.

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Just curious. Anyone try IFR rather than IMR? It seems like it would be a better choice for packs with multiples of three volts (ie 6V, 12V, 15V, 24V, etc). And they are very rugged, produce LOTS of amps, and have a nice, flat discharge curve.

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you’re welcome :slight_smile: I have a voltage monitor backed with velcro that I swap between whatever battery is being used. It flashes a warning when that cell drops below 3.4V, so it’s easy to keep an eye on discharge state.

haven’t heard of it, simply because those cells are relatively hard to get hold of. The high discharge cells (IMR?) are sometimes used, but most of the time it’s whatever’s been salvaged :slight_smile: I’d love to get hold of some high drain cells for packs that I can’t fit a 2P set up in, but I’ve never found an old pack to salvage and I’m not going to pay money for cells when I have a salad draw full of 18650s and lipos!

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Ok Ive had time on my hands since the last post, i followed the link and purchased the hp 12 cell pack for 15 bucks. Carefully i burned away at the plastic joint with a pencil torch andgotto the batteries. They are blue panasonics 2200mah. Wired 6 of them up with the balanced hobby charger setup which i borrowed from some old lipo batteries my brother had laying around. They were actually fullly charged. 22.8v for all 6 cells.

When i put it in drill 18v pack and hooked it up to the drill it runs several times within 30 secs but really weak and it dies out. I measure the voltage and its still high and after waiting like 30 secs the drill will run again but die out. I leaning towards giving up on these li ion and getting the original NiCd thoughts??

These drills pull lots of power with the factory 1.8 amp nicd now this 2.2 amp li ion is way weaker basically unusable.

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Sounds like you’re trying to run a drill on LiCo laptop cells. LiCo just can’t supply the amps a power tool needs. That’s why power tools run LiFePO4 or LiMn rather than LiCo. Also, remember that trying to draw this kind of current from LiCo is downright DANGEROUS!

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I love the people on this forum. Ohh well i built the pack and im running it on a dewalt snake light that I rigged up with a 6w mr16.

Will start looking into this new Lifep04. Thanks