Mine has 14 x 1.2v Li_ion cells.

 

I thought Li_ion cells are 3.6V

 

Have you taken one of the cordless/battery powered drills apart? The one (a Craftsman 18V ni/cd don't know the model number) that I took apart the motor is now where near what a corded one is. The cordless one has a small hobby motor size in it. High RPM motor with much gearing to bring the speed down and the torque up, to match a corded drill.

Yes I have had a DeWalt DCD996 apart recently. This is a modern Lithium tool with brushless motor, quite a different animal from the anemic NiCD tools of the relatively recent past. I can PM pics if you're curious but I don't want to discuss further here because TS already stated he has a small motor and it would be a distraction to the thread, but the motor was pretty impressive and I wouldn't be surprised if it drew 60A. The drill is rated 820 watts (Unit Watts Out*). 820W / 20V = 41A.

* UWO is DeWalt's unit to express mechanical power. I don't know why they needed to create their own engineering units unless it's to afford them the opportunity to inflate numbers while avoiding the criticism of abusing an existing unit that already means something, like the flak ShopVac gets for putting "5HP" on 120V machines that aren't capable of tripping 15A breakers. That said, if it really is an accurate mechanical power measurement, then it means electrical efficiency isn't represented, so current could be even higher than 41A.

 

I have a 18VDC portable drill which needs a new Li battery, but as is often, this battery is obsolete. Is there any way I can get this to work i.e. by sourcing a new battery or converting to 120 VAC?

Hello there,

I have a 9.6v Ryobi drill i used for a while then both battery packs died and that was only after about 6 months and hardly used.
I replaced the pack with new NiCd cells (Sub C) and it lasted another 5 years with not too much use.
I got tired of buying those expensive batteries (the good ones) so i converted it to 12v using a lead acid battery. It was 12v and about 8 ampere hours or about that. I already had two of those.
I used a heavy current diode, about a 50 amp rating, in series with the 12v battery and some decent wires for the power. I used a 12v cigar plug on the end and adapter so i could connect it to the 12v battery which had lug terminals. It gave the drill some decently life.

As others have been saying the current is high for these things. I measured mine at 30 amps putting a sheet rock screw into a wood stud, so you can see even with this drill which certainly is not top of the line, it drew quite a bit of current.

I dont think laptop batteries are made for that and what is important it they would not be rated for high current like that so it could actually cause a big problem the least of which the pack would die quickly. For currents like this you would need to get some really good Li-ion cells like those made by Sony. You know they can handle the current because the SPECS say they can, and that's about the only way you can know how well they will work for a drill. When you buy the cells they have a rating, and many of them do not go very high, but some actually do go up to 30 amps. Notably one of the Sony flat top models go that high and can also take a very high charge current too. You will probably need cells with tabs though so you can connect them into a pack and you DO NOT want to solder to any of them directly. The way they do it is they weld the tabs on so it's a very quick process. You can sometimes order cells with tabs or without tabs but the seller will put tabs on for you for a nominal fee.

What i found in the long run though was it was better to go out and buy a new drill, one that is known to work well. I used that Ryobi several times but then finally one day went out and bought a Makita and that thing beats the heck out of the Ryobi by a long shot. Not only does it have a large battery back (Li-ion also) it also has a quick charger that can charge the pack in about a half hour. So sometimes it is better to just put the money into something that will work even better than the old one would if you could fix it perfectly.

Good luck with whatever you decide to do, but also keep in mind rebuilding packs is not the simplest thing in the world to do it could get a little tricky.
You could try the 12v lead acid battery trick, although your drill may run a little slower with some loss of power.

 

Mine has 14 x 1.2v Li_ion cells.

NiCad and NiMH are 1.2V chemistries, but LiIon is 3.7V.

I suppose I could be unaware of some odd lithium chemistry that has a 1.2V potential but I would be gobsmacked. Are you sure, @MaxHeadRoom?

There is a NiCad version, could that be what you have?

​

 

I opened the battery compartment and they are NI-Cad, doesn't jive with the tool description!
Advertising dept error maybe???

 

@strantor I dug up the motor from the drill, it's a very common 775 PM brushed motor. The version with bushings not ball bearings. https://www.nbleisonmotor.com/RS-775-Dc-Micro-Motor-pd6675924.html

I have a newer brushless drill and they are much more powerful.

I used part of one of the drill batteries to make an adapter for a more modern battery to use in the impact driver that came with the drill. The left is the original battery, right is the adapter to use a Worx string trimmer battery.

 

@strantor I dug up the motor from the drill, it's a very common 775 PM brushed motor. The version with bushings not ball bearings. https://www.nbleisonmotor.com/RS-775-Dc-Micro-Motor-pd6675924.html

I have a newer brushless drill and they are much more powerful.

Those 775 motors seem to be all over the place with regard to power output. On the page you linked, 3 of them have stall current >100A, with the highest 12V motor being 143A and the highest 24V motor being 68A. I assume these higher power variants are what go into cordless drills; probably the 24V one for a 20V tool. So maybe my contrived calculation for cordless brushed tools based on amp draw of corded brushed tools wasn't completely out to lunch?

 

@strantor
I used part of one of the drill batteries to make an adapter for a more modern battery to use in the impact driver that came with the drill. The left is the original battery, right is the adapter to use a Worx string trimmer battery.

That's pretty clever. TS could do this, if nobody on ebay is making an adapter for the obscure Canadian Tire brand tool he has. Or if it is cost prohibitive.

 

That's pretty clever. TS could do this, if nobody on ebay is making an adapter for the obscure Canadian Tire brand tool he has. Or if it is cost prohibitive.

When I bought the string trimmer, it came with a very slow charger. They make faster chargers so I bought one. From time to time I needed the impact driver but didn't want to buy new expensive batteries for it. Looking at the craftsman battery and the Worx charger they were almost the same size at the parting line. so this is what happened. The Worx batteies are pretty cheap on Ebay so now I have 3 of them so there is always at least one charged and ready to go for whichever tool needs it.

 

I opened the battery compartment and they are NI-Cad, doesn't jive with the tool description!
Advertising dept error maybe???

Well, they made both, it seems. So who knows?