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?
cordless drill conversion
- Thread starter garry
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Leejohn
Elite Member
Boy I would like to do that myself. Maybe someone can come up with something.
k0ua
Epic Contributor
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
Epic Contributor
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
The automotive blade fuses/holders have less voltage drop than the glass type (AGC type).
James K0UA
NormL
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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:
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
Epic Contributor
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
James K0UA
BigBoyinMS
Silver Member
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.
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
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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
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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
Epic Contributor
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
James K0UA