Help me convert my old drills

[notagoodwelder]

I have several old battery powered drills that the batteries are completely toast on and they're not worth buying new ones. I'm looking for a transformer so I can run them on AC power. The charger seemed like a good candidate, but too little current to power the drill. I'm looking to basically use someone's trash or something I might have already. A microwave oven is the best thing I can think of now to get me down to ~18v AC. Then rectify to DC. Am I on the right track?

Thanks for any help

[DIYer]

Here are a couple of links that might help:

Homemade Conversion of Cordless Drill to Corded

Homemade Modified Battery for Cordless Drill

Homemade Cordless Drill Modification

[Christophe Mineau]

Hello,
That's a great topic,
I've been looking for something similar for a long time.
The reason is not that my battery pack is out of order, the reason is that whenever I have to screw something in my shop, (that's not so often, not every week end), my three battery packs are always flat.
And as I don't want to plan several hours ahead that I have to screw something, I use the cordless drill very rarely.
As I am in my shop, I have no problem with the cord, and would prefer to have a tool always ready to use, even with a cord, rather than an always flat cordless tool.
And I don't want neither to have the battery charger always plugged, in case of an hypothetical use ....

I've always wondered why the manufacturers don't do such corded power screw drivers. I sometimes use my electric hand drill, but I really miss the torque limitation and the speed is too difficult to control.

My drill has the bad idea to be 14.4 V, so I guess using something like a car battery charger of 12 V would not fit ?
However, would that be so damaging for the motor to be 12V powered instead of 14.4 V ?

Diyer, I like the third solution you provided, that's exactly what I need, but will it be possible to find a bridge rectifier or regulator to convert from 18V AC to 14.4 DC ?
There are also lots of solutions over the Web making use of Laptop chargers, but I never considered these kind of solutions as serious, I feel that the current pick in real use would be far superior as what they could supply.

Thanks notagoodwelder for posting the question, and sorry if I 'm invading your topic.
Christophe

[DIYer]

Hi Christophe. Good question. Since I'm just a tinkerer, I would not venture to answer your question offhand. That's an interesting topic to look at though.

[notagoodwelder]

Oh wow great links thank you so much DIYer, and Christophe the more the merrier! I've been studying up on electronics, motors etc and researching this has helped me understand a lot. I'm gonna go read up on those threads and bring back what I can derive from it all..

Christophe what you need to go down to 14.4V is a transformer. You should be able to find one that goes from 110 down to 14.4.

As far as I know running 12V will be fine on your 14.4V motor, it just wont spin quite as fast as with 14.4V. I could be wrong but from my research so far I think you'll be fine.

You can think of the bridge rectifier as essentially a check valve for electricity, only allowing one polarity through, therefore taking you from AC to DC needed by the motor. If you ran your DC motor on AC, the motor would just wiggle back and forth at whatever frequency the AC power is switching, 60Hz in US and 50Hz over the pond where you are. DC motors use permanent magnets around the rotor and AC motors use electromagnets that manipulate the magnetic field in relation to how the AC power cycles.

If you wanted a drill that ran on either AC or DC, you would just need to build your AC to DC conversion before the drill, and then just remove that cord and plug the battery back in. Essentially like a laptop charger, you could put it all on the drill and have a switch to toggle between your power selection, but your drill would be quite bulky and it sounds like you don't need all in one unit anyway.

I will let you know how mine goes and am happy to attempt my best at any questions you have.
Thanks again

[Christophe Mineau]

Thanks you notagoodwelder (nor am I ), I will follow up your progress.
I was talking about 12V, because I was thinking about the car battery charger I already have in 12V, instead of purchasing a new transformer.
I guess the car battery charger has already a built in bridge rectifier (4 diods), but do we need a capacity. I was thinking that the battery itself acted as a capacity, is it true ?

[DIYer]

Thank you for your last post, notagoodwelder. Learned something from it.

[notagoodwelder]

Thank you for your last post, notagoodwelder. Learned something from it.

Glad to hear that. Let me know if I can clear anything up

[culveres]

I may be wrong but I think a 12 charger puts out about 13.5 volts in order to drive the battery to charge. You can check this out with a volt meter.
What I want to do is use the old cl. Drills for something. I have already replaced them with newer better drills with torque adjust and variable speed.
it just seems a waste to toss the old ones when the motors gears and switches etc are still useable. Just keep thinking reading and sharing.

And variable speed

[Doc]

Am I thinking correctly here but you are basically looking to turn a cordless drill into a corded one, yes?

If so a 12v battery and a small inverter is all that is required. When researching something similar to this I found a lot of help from caravan and RV sites since this is the sort of thing they seem to do a lot of.

Personally I've always been torn between taking the battery case apart (usually just a fancy case holding stock rechargeable batteries in) or simply stealing the chuck from it to use in other projects

Like everybody else here on the site - nothing ever leaves my workshop once it's dead. simply repurposed

Regards

Doc