Cordless drill with a cord

[mklotz]

Probably one of the most frustrating tools in the hobbyist's arsenal is the cordless electric drill. It's undeniably handy but, if you're like me, dealing with the batteries is enough to make you wish that Maxwell and Faraday had just kept their discoveries to themselves.

I wanted to drill a single hole out on the patio. Not wishing to deal with stringing an extension cord through a window, etc., I reached for the Craftsman 12V drill my daughter gave me a few years ago. No the battery wasn't dead - it managed to revolve the chuck at a stately 33-1/3 rpm for about ten seconds. Then it was dead. The backup battery that came with the drill hasn't been able to hold a charge since its second recharge. I reached for the backup cheapy drill from HF and it could spin its chuck but only if I didn't hold on to it. I hadn't used it in about a month so, of course, the battery had run down.

After exhausting my repertoire of curse words in three languages I started thinking about the problem. The real advantage (at least to me, an occasional user) is not that they're cordless but that one doesn't have to string (110 VAC) extension cords to use them. (Sounds confusing but stick with me.) I wouldn't mind if the thing had a short cord attached to a battery if that battery was more dependable than the ones supplied with these drills.

The typical NiCd supplied has all sorts of "memory" problems that can interfere with it taking and holding a decent charge. The manufacturers don't supply charging instructions and the chargers they supply have no "smarts".

But 12V Sealed Lead Acid (SLA) are widely available in small size packages, have decent capacity, and can hold a charge.

So, I opened up the drill and found the battery contacts...

Attached a hunk of speaker cable with some brass screws...

and, voila, a corded cordless drill...

Now the thing spins like a banshee and has torque to spare. The drill draws about 1.5 A at top speed and the battery is a 5 A-hr so it should last for at least an hour or two of use. I've never done anything with a cordless that took longer than a few minutes of drill run time so I think I'm in good shape there.

Lead-acid technology is well understood and smart chargers are widely available and inexpensive. Mine delivers 0.75A so it should be able to recharge the battery in 6+ hours. I intend to leave it on trickle charge most of the time so it's always ready to go.

The voltage on more modern drill batteries has gotten higher than 12 volts but I expect a 12 v battery will still run most drills. Before investing any money in this scheme, try your drill with the car battery. (Ignore that last if your car is a Tesla :-)

[DIYer]

Thanks mklotz! We've added your Cordless Drill Extension to our Drilling and Drill Presses category, as well as to your builder page: mklotz's Homemade Tools. Your receipt:

Cordless Drill Extension by mklotz

tags: battery, cordless, electrical

[PJs]

Thanks Marv, that rung a bell for a lead acid I have for my 2 axis equatorial mount that's been sitting...a while and a 12V Ryobi drill I picked up at Restore for $8 (batteries are $25+ ). I had built a 12ga wire cage around it with a handle then put it in an old camera bag that was just the right size...portable and handy with pockets. I've seen these hacks before but this one hit home with your writing style!

These cordless drill/tool batteries are like Printer Ink...3 uses and the ink cost more than the printer. My C3 stuff I use all the time and finally got a 18V 4ah Li-ion for them at a price I didn't have to indenture my first born for. A world of difference to what it came with (1.5ah). I picked up one of those mini C3 vac/blowers and after 15 minute of use it blew the fusible link in the one of the 2 original batteries I had. Some engineer cacked on the current draw/heat load calcs. Li-ion has its pluses, but over heating danger and the link are the bane of them IMHO. I think you can push Lead acids a bit harder and they recover much better, plus capacities are reasonable, just larger typically.

Also wanted to say thanks for your gear ratio tutorial...definitely confirming to what I came up with for a solar powered music box I'm making for my grandson. Had to go from 2400 to about 60rpm with 2 singles and a double (8-50/8-56=~55rpm).

Thanks!! ~PJ

[Jon]

These cordless drill/tool batteries are like Printer Ink...3 uses and the ink cost more than the printer.

Exactly: Razors and blades marketing. My printer does it with toner. It prematurely throws a "low on toner" error, and refuses to print. Reinstalling the printer driver makes it work again.

[kbalch]

Same here. My HP color laser printer started squawking about low toner levels a month or so ago. A little investigation revealed that the black is down to about 30%, while the colors are just fine. Replacing the black cartridge alone is going to be ~$80. A full set of cartridges is over $200 - for a sub-$200 printer!

Madness.

[PJs]

Exactly: Razors and blades marketing. My printer does it with toner. It prematurely throws a "low on toner" error, and refuses to print. Reinstalling the printer driver makes it work again.

Good Read on the link and something we shouldn't stand for at some level, IMHO. I'm all right with a proprietary design having higher cost at the git go but down the road with innovation in mfg, pass on the savings and promote some good will instead of milking every last drop and bad will, plus adding to the waste stream. Wondering now whether that was an engineering error with the C3 vac/blower because they had some issues with their reciprocating saws too. Life Cycle Planning or Planned Obsolescent...Oh My, what happened life time engineering. ~PJ

P.S. I have 2 Epson Ink Jets B-size and an all in one and it takes an hour and a half to reload on 5 machines.

[hants2]

Probably one of the most frustrating tools in the hobbyist's arsenal is the cordless electric drill. It's undeniably handy but, if you're like me, dealing with the batteries is enough to make you wish that Maxwell and Faraday had just kept their discoveries to themselves.

I wanted to drill a single hole out on the patio. Not wishing to deal with stringing an extension cord through a window, etc., I reached for the Craftsman 12V drill my daughter gave me a few years ago. No the battery wasn't dead - it managed to revolve the chuck at a stately 33-1/3 rpm for about ten seconds. Then it was dead. The backup battery that came with the drill hasn't been able to hold a charge since its second recharge. I reached for the backup cheapy drill from HF and it could spin its chuck but only if I didn't hold on to it. I hadn't used it in about a month so, of course, the battery had run down.

After exhausting my repertoire of curse words in three languages I started thinking about the problem. The real advantage (at least to me, an occasional user) is not that they're cordless but that one doesn't have to string (110 VAC) extension cords to use them. (Sounds confusing but stick with me.) I wouldn't mind if the thing had a short cord attached to a battery if that battery was more dependable than the ones supplied with these drills.

The typical NiCd supplied has all sorts of "memory" problems that can interfere with it taking and holding a decent charge. The manufacturers don't supply charging instructions and the chargers they supply have no "smarts".

But 12V Sealed Lead Acid (SLA) are widely available in small size packages, have decent capacity, and can hold a charge.

So, I opened up the drill and found the battery contacts...




Attached a hunk of speaker cable with some brass screws...



and, voila, a corded cordless drill...



Now the thing spins like a banshee and has torque to spare. The drill draws about 1.5 A at top speed and the battery is a 5 A-hr so it should last for at least an hour or two of use. I've never done anything with a cordless that took longer than a few minutes of drill run time so I think I'm in good shape there.

Lead-acid technology is well understood and smart chargers are widely available and inexpensive. Mine delivers 0.75A so it should be able to recharge the battery in 6+ hours. I intend to leave it on trickle charge most of the time so it's always ready to go.

The voltage on more modern drill batteries has gotten higher than 12 xolts but I expect a 12 v battery will still run most drills. Before investing any money in this scheme, try your drill with the car battery. (Ignore that last if your car is a Tesla :-)

I did almos the same thing with a 12v makita except put apair of alligator clips from a dead battery charger, i use it on the battery in my truck. will change to your system when i get your style bat. clips don't keep a good connection. great use of otherwise throwaway

[Philip Davies]

I'm going to try this with my 12v makita too. Charger works ok but not worth buying new batteries, not now there are much handier 10v ones that perform better. Thanks!

[mklotz]

In all fairness I should point out that since doing this I've acquired a Milwaukee drill with the M-12 lithium battery. It works wonderfully, is powerful, and the battery holds a charge forever. It's the same battery as used in my Milwaukee Dremel clone described elsewhere on this site.

The Craftsman drill with the SLA battery still sees constant duty in the shop and out-of-doors where the presence of the cord is not an issue. Regardless, there are still situations where even this short cord can be an encumbrance hence the purchase of the Milwaukee.

[Christophe Mineau]

Yes, I see we are several preferring a cord than an always flat battery.
I did mine with a LED power supply, it was a 14.4 V but works perfeclty fine on 12V as well
Homemade Cordless to Corded Drill Modification

Actually, I've always thought that the annoying thing with the wireless technology, it is that sooner or later, we miss the wire.
(No, I'm kidding, I actually work in the telecom industry making 4G base stations )