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There was a couple of questions on how to power a cordless drill, but they are all about power supplies. I've got a DeWalt 10.8V cordless drill and its battery connects through 4 pins instead of 2 or 3 that I've seen while googling. One is 12V, second 8V and to others seem to be ground. I've tried connecting only 8, only 12 and both (with common ground) but non of that worked. I know the polarity is right because a little diode under the chuck flashes for a second when I try to run it.

Maybe someone dealt with this kind of battery connection or knows the right way to power a DeWalt cordless drill? enter image description here

MrCheatak
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  • So this question is in a grey area (repair questions are off topic) What are you intending to do? Are you trying to power your drill with a supply? – Voltage Spike Feb 24 '17 at 18:22
  • @laptop2d Yes, with a bench power supply. – MrCheatak Feb 24 '17 at 18:24
  • I would use the appropriate DeWalt battery. – Peter Bennett Feb 24 '17 at 18:40
  • @PeterBennett Both batteries that were included are functioning. I just need it to work for an extended period of time. – MrCheatak Feb 24 '17 at 18:43
  • Then use the charger with battery. But beware thermal rise in motor is a problem. Get the right tool. – Tony Stewart EE75 Feb 24 '17 at 18:48
  • @TonyStewart.EEsince'75 If I had, I would. Even with a charger I don't think it will last for more than an hour and a half. – MrCheatak Feb 24 '17 at 19:35
  • The only known point, without further investigation, is the fully-charged voltage on the battery. So, remove the cells and apply that voltage, with an adequate current capacity, to the terminals where they used to be. I suggest using a diode with a generous current rating from the PSU, and accounting for the voltage drop across the diode, to reduce the chance of damaging the PSU. As Tony Stewart implies, careful monitoring of the drill temperature could be desirable. If the cells are individually monitored, this idea may not work. – Andrew Morton Feb 24 '17 at 19:52
  • @AndrewMorton the idea to use power circuit is great, but as you highlighted it won't work if batteries are monitored individually. Sadly, but they are. Blue and brown(under the terminals between 1st and 2nd batteries) wires are serving that purpose. – MrCheatak Feb 24 '17 at 20:01
  • @MrCheatak OK, and I assume you realised I meant disassembling a battery pack, apply 10.8 V to the terminals for the end + and -, and use a voltage divider to get 3.6 V across the other two cell connections. N.B. A battery is a collection of cells, in case that nomenclature is not known to you. – Andrew Morton Feb 24 '17 at 20:09
  • @AndrewMorton yes, that are 3 18650 batteries 35A rated each. I know that's a lot of amps, but I won't need all of them. You mean a resistor-based voltage divider? It won't handle even 5A. – MrCheatak Feb 24 '17 at 20:20
  • @MrCheatak At a guess, the monitoring circuitry will only be looking at the voltages across the cells so it will have a high impedance. So three 10 kΩ 0.25 W resistors should be fine for the voltage divider. If not, they will send you a smoke signal. This is all at your own risk. – Andrew Morton Feb 24 '17 at 20:25
  • I think you'll find that your bench supply can't provide enough current for the drill. At full torque it probably does use 30 A. The wires to carry this current without unreasonable voltage drop will be heavy too. – tomnexus Feb 24 '17 at 21:58
  • @AndrewMorton well, I'll give it a try and give a feedback – MrCheatak Feb 24 '17 at 23:44
  • @tomnexus yeah, but mine is capable for about 25A 12V and that's more than I'll need. Though wiring is a point. – MrCheatak Feb 24 '17 at 23:48

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