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Hello. This is my first post to any type of group. Thanks for sharing your knowledge. I know very little about electronics so I need your help with a money saving project. I have a 12 volt cordless drill that has no battery. Since a new battery sells for over $30, I had the idea of somehow hooking up a homemade 12 volt battery pack made from 10 rechargable NimH batteries. Soldering to the drill's two metal battery clips would be feasible. Will I run into any problems with current..etc? Can I also hook this up to a deep cycle or car battery? I was unsure If I would encounter problems relating to amps...does the drill's motor automatically o draw only the power it needs?

Thanks in advance. Jay

Reply to
Jay
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If the cells fit in the available space, it should work.

The only risk from very high available current would be when you stall the motor. Then the current is limited only by the resistance of the motor and the internal resistance of the battery. As long as the motor is turning at a reasonable speed, it generates a voltage that bucks the battery voltage and keeps the current reasonable, regardless of how large the battery current capacity is.

You can buy NiMh cells with solder tabs already welded on them. but at about $3 each, 10 of them will cost you about $30.

Reply to
John Popelish

Hey! Thanks guys for your quick and excellent answers. Don't throw away your old cordless drills

Reply to
Jay

Plenty of boat owners have converted their drills to run off a boat or car battery. Use good quality wire that can handle at least 10 amps. Double insulated wire like mains flex is better for a hand tool as its more abrasion resistant. It should be long enough to get anywhere on the vehicle or boat. MAKE SURE the wire is properly secured at the drill end. At the other end fit a cigarette lighter plug fused at 10A and also make up a short lead with a couple of battery clips, a 10A inline fuse and a 'free' (cable mounting) cigarette lighter socket. Get the polarity right. Cigarette plugs are centre +ve.

If you have an old dead battery, break it open and fit the cable using it at the drill end. That way you can still fit a good battery later when you need it too far from the car/boat.

For anyone else, the drill to be converted needs to be 12 V or 15 V. (Some people have over-powered slightly lower voltage drills successfully - NOT RECCOMENDED)

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Reply to
Ian Malcolm

Hello Jay,

Just one more comment: If you hook it up to a large battery like a marine deep cycle or a car cigarette lighter plug make sure to install at least an inline fuse. An automotive parts shop should have those. There is always a risk that the cable or drill shorts out and you don't want to see your boat or whatever you are using it on go up in flames.

Regards, Joerg

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Reply to
Joerg

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