cordless drill conversion

[garry]

I have a cordless 9V Black and Decker drill whose batteries are no longer chargeable. I would like to wire it so I could power it with the 12 volt battery on my tractor. I took the battery apart and noticed there is what looks like a capacitor on top of the existing battery. If I solder jumper wires to the drill will I have to include the capacitor in the circuit? What purpose does the capacitor serve? Can I do what I am trying to do?

 

[Leejohn]

Boy I would like to do that myself. Maybe someone can come up with something.

 

[k0ua]

I have a cordless 9V Black and Decker drill whose batteries are no longer chargeable. I would like to wire it so I could power it with the 12 volt battery on my tractor. I took the battery apart and noticed there is what looks like a capacitor on top of the existing battery. If I solder jumper wires to the drill will I have to include the capacitor in the circuit? What purpose does the capacitor serve? Can I do what I am trying to do?

The "capacitor" is likely a thermal fuse not a cap.
A fuse inline in the power cord of your new 12 volt feed would be a good start, right next to the clips for attaching to your battery. Post a picture of the device and maybe we can help a little better.

James K0UA

 

[k0ua]

Let me clarify one of my statements, the fuse needs to go next to the tractors battery, not the battery connections on the drill. so that the power cord is fused at the source of power . I would not worry about the thermal fuse in the battery pack, it is there to open up the battery connection if the pack overheats. As for fuse size I would measure the current draw with your VOM, most will go to 10 Amperes and I doubt your drill will draw anywhere near that. Then fuse about 1.5 times higher than that amount.
The automotive blade fuses/holders have less voltage drop than the glass type (AGC type).

James K0UA

 

[NormL]

Garry, you indicate at the outset that the drill is a 9 volt and you want to hook it to a 12 volt tractor battery. That might do two things: 1): boost the power of the drill. 2): start it smoking and shorten the life of the drill.

I could be wrong, of coarse - would not be the first time!:laughing: Maybe someone with more knowledge on the topic can set me straight.:thumbsup:

 

[k0ua]

It will be allright, I have done it before, You are right of course about the overvoltage, it will make it run a little faster, and get a little hotter, but the length of the wire will drop the voltage some, especially if he does not use too large of a guage of wire, just enough to carry the current, maybe 18 depending on what the current is.. (that is also why I suggested measuring the current) most of those small DC motors will run ok with some overvoltage. All should be well.

James K0UA

 

[BigBoyinMS]

I've read in the past that it's no problem hooking up directly to a car battery no matter the voltage of the drill. Lower voltage drills run faster and higher voltage drills run slower. As said earlier, they may not last as long if the voltages are different but it's basically junk otherwise.

There is a way to fix your old battery that has quit holding a charge. Car batteries will get a coating on the plates called sulfation. You can buy a battery charger that will basically burn off the sulfation. Basically a controlled overcharge. Cordless batteries have a similar issue that makes them die. You can "repair" them in a similar way as the car batteries. There are numerous Youtube videos and online how-to's if you want to try that. Some use a car battery to do it and some use a welder. Something to look into.

 

[sixdogs]

I had an old Makita 7V drill with a bad battery and learned the 9V battery would fit in the slot. That was over 10 years ago and with lots of use. Runs a little faster but works fine. It's not a car battery but it's what I did.

 

[SPYDERLK]

Let me clarify one of my statements, the fuse needs to go next to the tractors battery, not the battery connections on the drill. so that the power cord is fused at the source of power . I would not worry about the thermal fuse in the battery pack, it is there to open up the battery connection if the pack overheats. As for fuse size I would measure the current draw with your VOM, most will go to 10 Amperes and I doubt your drill will draw anywhere near that. Then fuse about 1.5 times higher than that amount.
The automotive blade fuses/holders have less voltage drop than the glass type (AGC type).

James K0UA

Low voltage drills will draw well over 10A when working, and even more at stall. Ill guess at least 50A for the OP model. I have measured 9A at stall for a 120V drill. Thats over a kilowatt.
larry

 

[k0ua]

I will bet a dollar (yes I will send you the dollar!) that his little Black and Decker 9 volt wont draw 10 amps under full stall at 12 volts. One way to find out is to measure it.! Thats why I suggested to measure it. Then we can size the fuse and the wire size a little better. Sure I am guessing, but so are you, without measuring it is all just speculation.

James K0UA

 

[SPYDERLK]

I will bet a dollar (yes I will send you the dollar!) that his little Black and Decker 9 volt wont draw 10 amps under full stall at 12 volts. One way to find out is to measure it.! Thats why I suggested to measure it. Then we can size the fuse and the wire size a little better. Sure I am guessing, but so are you, without measuring it is all just speculation.

James K0UA

Its a bet. If the OP will put various value standard blow fuses wired into the feed wires itll give an ~answer w/o the need for measuing equip. He should use 12ga wire and iterate up or down from 30A as indicated by fuse survival for a minimum of 3 sec at stall. [A fuse wont blow at its rating and typically a std fuse will take a second or two to blow when conducting twice its rating.]
larry

 

[k0ua]

Its a bet. If the OP will put various value standard blow fuses wires in the feed wires itll give an ~answer w/o the need for measuing equip. He should use 12ga wire and iterate up or down from 30A as indicated by fuse survival for a minimum of 3 sec at stall. [A fuse wont blow at its rating and typically a std fuse will take a second or two to blow when conducting twice its rating.]
larry

Sounds like good methodology its a deal. (what was that address again)

James K0UA

 

[SPYDERLK]

Sounds like good methodology its a deal. (what was that address again)

James K0UA

Dont worry about it. Lets see if we can get him to try it and report.:thumbsup:
larry

 

[k0ua]

Yeah hard to say what the OP will do. of course some depends on the size and the length of wire he uses. I was thinking the little B&D 9.6 volt was a pretty anemic drill and not having much torque was likely to have a small current draw.

James K0UA

 

[SPYDERLK]

Hard to ask him to hold his motor at or near stall for several seconds. Things heat up pretty quick. No way to be sure on his drill. Youll see tho on the specs of AC handrills that they fall in the range of 2 to 4A rated running current. The lower of that is truly anemic. At 12V you need 10x that. Then near stall it goes up another factor of 2. The ability of NiCads to deliver current is astounding ... the better part of 100A from a "C" cell. Not for long but plenty of grunt while it lasts. NiMh cells pack more energy but cant deliver the current ... so the drill can run lite duty longer, but cant put out hi torque at all.-- And lithium has it all.
larry

 

[garry]

Thanks for all the replies and encouragement. I will get some supplies next week and give it a try. I will keep you posted.

 

[schmism]

I converted one of my old 12v drills to be corded and attached to a lawn mower bat.

I just soldered 2 wires to the pads on the side of the old cordless bat. that way the drill itself has not been modified and i can use the cordless as one if i ever get around to rebuilding one of the other 12v bat packs.

 

[PILOON]

I have opened a few battery drills and repaired many.
I noticed that be it 7.2, 9 or 12 volts the motors all seem the same.
True I did not measure winding resistance but swapping parts around generally worked OK.
I also have wired some drills to the cigar lighter plug and it is sure handy to have.
Most lighter plug adapters have fuses built in.

 

[crbr]

Thanks for all the replies and encouragement. I will get some supplies next week and give it a try. I will keep you posted.

Thank you....

 

[handirifle]

Well, I have an old Makita (I think I still do anyway) whos battery died and I have lost the charger. The battery dies many years ago, but I kept it all thinking someday I'd buy a new battery, went with a corded drill instead.

The posts here now have me thinking. I tried some of the "youtube" ideas on refreshing the battery, to no avail, but other ideas here are intriguing.