Dewalt cordless drill 18 volt battery cheat

This video shows how to make an otherwise useless 18 volt Dewalt rechargeable battery into a useable power source for your cordless power tools. I have been working in areas where I do not have access to my Dewalt battery charger and/or a 110 volt power source to plug my 1-hour charger into. Normally, you are dead-in-the-water with cordless power tools – until now! Relatively simple cheat using readily available parts that you can get at any electronics store. When completed you can use a car battery or any other external DC power supply from 12 to 18 volts to run your tools. This video is for educational purposes only and is not meant to deprive Dewalt of a battery sale.

Filed Under: Cordless Power Tools


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  1. aboonski says:

    No inverter is used here – just the power from the vehicle batteries and the alternators when the truck is running. I suppose I could set up an inverter in the truck to run the charger for the Dewalt batteries but at the present time I don’t even have one good 18 volt battery to charge. I use this systen to run all of my Dewalt power tools and I am satisfied with the results. You will see “white blackbirds” when I pay $90 for a new 18 volt Dewalt battery!

  2. manadio says:

    power inverter in the back of the car?

  3. TwistedGambino says:

    you are the man ….. looks like you a ninja by trade lol

  4. pudodrewculous says:

    I work on tools like this… 12v will work, but on the vast majority of tools, running on a different voltage is hard on the tool… if you have a 12v tool set, this is actually pretty cool idea… But if you have 18v or higher (24v or 36v) youre pushing your luck… it’ll get toasted quicker than normal… but if you are in a pinch, this will work pretty well

  5. aboonski says:

    As your batteries start to “fade”, the voltage tapers off and so does the power and RPM the drill can obtain – but it still works fine with less voltage only slower. Provided you do not bog the drill down it will be just fine with the lower voltage. I have run my Dewalt 18 volt tools with 12 volts on many an occasion prior to finding out how well they run via my 24 volt NATO plug application. Just don’t expect the same performance with the lower voltage than that of the 18 volt battery.

  6. aboonski says:

    You are very welcome! Thanks for posting a positive comment for me.

  7. aboonski says:

    You mean a “selector switch” – that’s a Great idea and something I just might do. I figured by now that Dewalt would lower the price of their batteries but no such luck! It would require tapping the positive lead inside the battery with a two-way switch which would allow external power to get to the business end of the battery (where it plugs into the tool) and then you could bave your cake and eat it too!

  8. aboonski says:

    It would work but I would recommend using one of the 12 volt tools and not the 18 volt ones because of the power drop that comes with the use of a long power cord. It’s all about resistance…

  9. aboonski says:

    Should work just as well as the Dewalt tools do on 12 volts. Twelve volts DC is twelve volts DC whether it comes from a dry cell battery or a car battery. You can hook two of the 6 volt lantern batteries together in series to power your drill also. My next project will be to rig up a series of 12 1 1/2 volt ‘C’ rechargeable batteries to power my Dewalt tools. I should be able to charge them with the Dewalt charger too.

  10. Mah3525 says:

    I have 2 of the Skil 18volt drills, so they will run on 12 volts fine?
    I want to rig mine up to a 12 volt jump battery back for mobility.
    So with 12 volt it won’t hurt the drill ?
    Just run a little slower ?

  11. defendant420 says:

    Hmm that would be awesome connected to a cigar lighter connector and like 25 ft long wire.

  12. chickenpoper says:

    you should of made it so the battery had it guts but it had a switch that changes to off,external,internal so you could always just use one battery

  13. toolreviews says:

    oh ok I see what your talking about in your reply, and is it possible to make the wires longer to use on a Job site that has no gas in the gas powered generator?

  14. aboonski says:

    I am not charging the battery in this video; this is a battery pack by-pass (no cells in the battery pack). Ironically, Ryobi does sell a charger that plugs into the cigarette lighter – I bought one of them for my Ryobi tools. I am down to one Dewalt 18 volt battery now and it is starting to fail. With my “battery cheat” I will never need to buy another Dewalt battery again but will have to use a “cord” to power my 18 volt Dewalt tools from now on. Thanks for the comment!

  15. aboonski says:

    Thanks for the comment! This really works for me! $86.00 plus tax for a new 18 volt Dewalt battery is just too much money for a battery that does not last long.

  16. aboonski says:

    Actually I am not charging the battery here but using the 24 volt system in my military truck to run my 18 volt Dewalt power tools. I have removed the guts from the battery pack and direct wired the empty battery case so that I can pipe the power into the drill (or other tools) from an external source – that could be anything from a transformer to a bunch of ‘D’ cells hooked in series to come up with sufficient voltage to run the tool.

  17. toolreviews says:

    I have to say charging the Dewalt cordless drill on a car battery is very creative indeed… Thanks for sharing!

  18. mrpowerchute says:

    I’m pretty sure a 12V charger would be the way to go here. It still only takes an hour to charge up one of these bad boys. These batteries are great. I just now replaced two of these I’ve been using on a daily bases for ten years.

  19. team39763 says:

    I just did this to my Skil 18v battery. Thanks for posting this vid, it helped me a lot. My batteries are about 3 years old and one only holds a charge for a few minutes and never fully recharges. I wasn’t looking forward to buying new batteries and this works better for me at the moment. Take care man.

  20. xADEAN4DIMEx says:

    lol man battery costs are ridiculous

  21. aboonski says:

    Thanks for the compliment – I AM a redneck accordig to my fiance. Dewalt batteries just cost too much and don’t last. Aside from not being able to use my Dewalt cordless tools I figured this to be an alternative to letting them sit and rot. Thanks for posting the comment!

  22. xADEAN4DIMEx says:

    only a redneck would make something like that just buy enough batteries and you wont have to use ur truck. lmao

  23. nookie077 says:

    i still laugh about it today too.

  24. ramfackled420 says:


  25. aboonski says:

    Generally I do but at the same time that increases the voltage substantially where I pull the power from. With a really long extension cord this is not a problem because the length of the cord drops the voltage down when you are drawing power from it.

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