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not so cordless drill

Discussion in 'General Electronics Discussion' started by donkey, Aug 7, 2011.

  1. donkey

    donkey

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    Feb 26, 2011
    got a project i have been trying to figure out for a little while. we all use cordless drills but i want the option to plug it into the mains(via a transformer) when both my batteries are flat. question is how do i find the right transformer? I know its 18v but thats all i know
     
  2. poor mystic

    poor mystic

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    Apr 8, 2011
    Well then, how many watts ya got? What power to max out the drill?
     
  3. duke37

    duke37

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    Jan 9, 2011
    The battery is DC so your supply must be DC and connected the right way round. The 18V battery may not give 18V under load, so a lower voltage may be adequate.
    I suggest using a 12V simple battery charger of adequate current rating feeding the fattest capacitor you can find. You will get more than 12V out, probably 16V or so and this should not drop much under load with a powerful charger.
     
  4. donkey

    donkey

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    Feb 26, 2011
    will give what little details i have. the charger has 240v 5ohz 75w in 18v 1.9A/34va out
    the drill is a ryobi CID1802P the battery has serial number 130109021. both the battery and drill only say 18v no other info.
     
  5. daddles

    daddles

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    Jun 10, 2011
    Hook the thing up to a DC power supply and measure its current draw under operating conditions. You'll have to do something like this in order to select a suitable power supply. Remember to operate the drill under a heavy a load, as that can increase the current needed markedly. I'm guessing it will draw quite a bit more current than you suspect it will.
     
  6. davenn

    davenn Moderator

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    I have a couple of cordless drills with stuffed battery packs that I now run off DC PSU's.
    no big deal :) unsing the Manson variable V and A supply from jaycar, they run hppily at their stated voltage and drawing anything from 2 - 3 amps


    Dave
     
  7. donkey

    donkey

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    Feb 26, 2011
    davenn thanks. I am still new to electronics and haven't got a bench supply yet (my missus says not yet... but i want a new toy...)
    the question i have is could i simply use an 18v transformer with about 5amps or would that be too much? or too little? i cannot figure out how to test the device without pulling it apart, and i don't want to do that as its still new. I just want a backup in case the batteries go flat
     
  8. poor mystic

    poor mystic

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    Apr 8, 2011
    Hi Phil
    18V is the right emf, and with 90W available it'll do most jobs. However I bet the drill can eat a lot more than the transformer can supply, when it is under heavy load.
     
  9. donkey

    donkey

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    Feb 26, 2011
    cool thanks Mark.
    its just an idea I wanna play with for now. i just don't know if i get a transformer with too many amps if that'll cause problems. I know if its too low the drill won't turn.
    the charger stats are 18v 1.9A/34va out and it takes about 2 hours to fully charge a flat battery... could i use that to figure out the best tranformer?
     
  10. daddles

    daddles

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    Jun 10, 2011
    I've been using cordless drills for 25+ years and the ones you buy today are much better than the older ones. Manufacturers figured out that the drills weren't much use when they just supplied one battery, so they typically come with two batteries. One can be charging while the other is working.

    My son-in-law likes the heavy Dewalt drills because he can get most of a day's use from one battery charge (he's an HVAC technician and can really put a load on a drill). I just do home projects and prefer a lighter drill. My little $100 Hitachi drill suits me nearly perfectly.

    If you're not doing commercial work with it, I suspect you'll never have problems with the batteries being dead (it will happen though when you reach the end of life of the batteries). Thus, I feel you don't need a separate power supply.

    Besides, if you're really worried about this, get a backup corded drill. I have two Dewalt corded drills that I use as backups to my cordless drill. I think they were around $60 new (probably a bit more now) and have substantially more torque than the cordless drill, as does my 1/2" Milwaukee corded drill. And for really tough stuff, I use my Rockwell 1/2" impact driver I bought 35 years ago. But virtually all of the drilling etc. I do outside my shop is done whenever possible with the cordless drills because they are so convenient.
     
  11. donkey

    donkey

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    Feb 26, 2011
    but if i buy a corded backup... i wouldn't be able to blow up the one i have now.... I mean experiment and expand my knowledge
     
  12. davelectronic

    davelectronic

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    Dec 13, 2010
    RE not so cordless drill

    Hi there, my cordless drill is old and 18 volts, it came with two batterys, they dont hold a charge to good now, age i think, ive modded a pc atx power supply to run my drill, yes its de rated to 12 volts, but for me thats fine as i only use it on light duty and it supplys all the current i need, any transformer and rectifier combo will do, motors in these drills are not fussy on regulated power, be sure your supply can meet the current needs, and some in reserve. Dave.
     
  13. poor mystic

    poor mystic

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    Apr 8, 2011
    Good one Davelectronic.
    so now you know, Phil, and about all I want to add to what you've heard is make sure it looks really tidy - as though it came out of a shop - so your girlfriend is impressed.She's a big part of your life and it'll help for her to think you're doing something positive and valuable with your time, not just wasting time. You'll soon want her support for your extended electronics activities!
     
  14. donkey

    donkey

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    Feb 26, 2011
    thanks everyone. time to get out the duct tape and empty ice cream containers to make a housing (kidding... i use normal tape lmao)
    ty so much this is for light duty so i think i might go for something low amp
     
  15. peterlonz

    peterlonz

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    Feb 11, 2010
    An old post I know.
    But some info I have gleaned while thinking along similar lines:
    Good cordless drills can almost match corded drills in power output.
    Typically a corded drill is rated around 450W, depending upon type brand & size.
    If a PC ATX PSU is considered you are limited to 12VDC & about 15 to 20 amps; not sufficient with a cordless 18V unit.
    If a 500W PSU is considered, output voltage is typically 12 or 24 VDC; neither is ideal but probably the 24 VDC option will work on intermittent duty which is what we see in most non-commercial applications.
    I don't know of a perfect solution which does not involve building a new battery pack.
     
  16. majoco

    majoco

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    Nov 10, 2019
    I have had a small Ryobi cordless drill for many years that has two internal batteries about "C" or "AA" size. I often use it with the charger attached in a small bench vise for all sort of cleaning/polishing/wire brushing tasks. It has a planetary gearbox between the motor and the drill chuck so it's got plenty of grunt. I'm on my third set of batteries now and a non-standard 6 volt wall-wart charger and it still goes very well - and over the years it's been very cheap to run!
     
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