Charging power tool battery on 12v system - possible?

Discussion in 'Tech/Mech General' started by magicsurfbus, Jan 23, 2015.

  1. magicsurfbus

    magicsurfbus Funster

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    I carry a Black & Decker 12v power drill/screwdriver in my MH.

    I've got a working battery charger base with a two core cable linked to a knackered 230v 3 pin power pack.

    The power pack has the following ratings on it:

    230v ~ 50 Hz 12.0W
    14.5V 220mA 3.2VA

    If I removed the knackered power pack could I safely fix the two core cable to a 12v lighter plug with the correct fuse and recharge the battery from the cab lighter socket on long drives? If so, what fuse would I need and which cable would I fit it to?

    Ta in advance.
     
  2. Tootles

    Tootles Funster

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    Well, I regularly charge most 12 volt stuff off the narrowboat with the engine running very successfully. However, that is mostly low ampage draw, except a large spotlight with quite a big battery, however, that charges fine as well. Try it and see.
     
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  3. pappajohn

    pappajohn Funster Life Member

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    The lighter socket is already fused...probably at 10a if its the cig lighter or 15a if its an auxilary socket so no fuse needed.
     
  4. steevie

    steevie Funster

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    It may well get hot if you charge it with the engine running, which could be giving out anything between 35 and 65 amps. Best to try it just from the batteries first.
     
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  5. tonyidle

    tonyidle Funster

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    It will only what it needs - much less than 1 amp probably.
     
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  6. pappajohn

    pappajohn Funster Life Member

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    Better keep an eye on my tomtom then......my alternator produces 180 amps ;)

    The drill battery will only take what it needs and the alternator will only output what is needed.
     
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  7. Peter A Forbes

    Peter A Forbes Funster

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    It depends on the battery.

    If it is Nicad then it will take a LOT of current and probably damage something, which is why they are charged with constant current supplies.

    If it is one of the Lithium types then it may explode if it doesn't have regulation built in for the battery charging.

    NiMH is the same as Nicad for charging purposes.

    Good way to end up in A&E at your local hospital.

    Peter
     
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  8. John Laidler

    John Laidler Funster

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    I think you would be better off with a wee inverter.*


    *Which is not one of those things for helping you clear a 5 bar gate.
     
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  9. magicsurfbus

    magicsurfbus Funster

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    With a charging load of only 220mA I'm a bit wary about just sticking a 12v lighter socket onto what is basically a battery holder then letting rip with the alternator. I haven't a clue what battery type it is either, even after removing the cells from a duff one. There's no labelling.

    I''ll probably leave it and just charge a couple of batteries up from the mains before I set off. It's not like I use them much unless I need to repair something.

    Thanks for the tips.
     
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  10. TheCaller

    TheCaller Funster

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    Whether the above applies in this case will depend on which of the following two quotes from the OP reflects the true position.

    If the first applies and it's a working battery charger that draws what it needs from a 14.5V 220mA 3.2VA power supply, then connecting it to the cigarette lighter socket while the engine is running should be fine. This implies that any control or intelligence required is contained within the charger.

    If the second applies and the battery really is plugged into what is no more than a means of holding it & making the connection to the now duff power supply, then there is a possibility of over-charging the battery & possibly also blowing the fuse.

    There is a third possibility, which is that the battery casing itself contains not only the battery, but the circuitry to regulate the charging.

    Personally, my money is on the first scenario being correct.
     
  11. chaser

    chaser Funster

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    Don't know about the workings of the cig socket but there are loads of things that come with a mains charger and a cig plug so they must work on either, a large 1000000 candle watt torch in my case has never been any trouble.
     
  12. magicsurfbus

    magicsurfbus Funster

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    Connecting just the working battery base to the 12v socket is like running two wires direct from the alternator to the battery with no intervening regulation apart from the fuse in the 12v plug. I can't help thinking the (now defunct) 3-pin power pack has some sort of regulators and safety cut outs built in. I'm not going to risk it.
     
  13. pappajohn

    pappajohn Funster Life Member

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    I have yet to see a 12v drill with a self contained plug-in power supply.

    Every one I know of has a charger unit with a flex and 3 pin plug.
    The battery sits in the charger.

    My understanding of the thread is the charger is buggered and the op wants to connect directly from battery to drill battery.
     
  14. pappajohn

    pappajohn Funster Life Member

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    Just re-read the first post and see it a black and decker...
    Basically a toy drill which, like a lot of B&D stuff, charges off a wall charger with a basic battery holder.

    Easiest option is buy a new universal 12v wall charger off eBay...around £6
     
  15. Mattyjwr

    Mattyjwr Funster Life Member

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    Just wondering what you use it for.
     
  16. magicsurfbus

    magicsurfbus Funster

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    [​IMG]
    The left bit is knackered, the right bit has two metal terminals to link to the battery and that's it. I'm thinking that connecting the right bit direct to a 12v socket is probably silly.

    These units are bloody useless - first sign of a battery fault and they fail on you forever, then they cost £20-30 to replace. I had three B&D implements that used these chargers and all three have failed. As pappajohn has suggested I've already bought a compatible universal charger but for a bit more than £6.
     
  17. magicsurfbus

    magicsurfbus Funster

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    Drilling holes and putting screws in. Or maybe I've misunderstood your query?
     
  18. tonyidle

    tonyidle Funster

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    If the left part is marked with it's output as suggested in your first post you can cut the wire close to the unit, discard it, and fit a cigar lighter plug. It's important that you observe the correct polarity but other than that there is no problem charging from any 12v - 15v source - a vehicle cigar lighter socket is ideal.
     
  19. Mattyjwr

    Mattyjwr Funster Life Member

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    I've spent loads of money on drills etc but am about to dump them as they are too tired to be of any use - the batteries don't hold their charge and even if I take them straight off the charger, the torque is useless. I have replaced them with a 10.8v Makita combi drill driver that does not discharge its battery while in the cupboard and am about to buy something more powerful for bigger projects. I haven't, however, found any use for them when in the mh and was wondering if I have missed a trick.
     
  20. magicsurfbus

    magicsurfbus Funster

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    Well it's handy to have a power drill in the MH if something falls off or needs fixing on holiday. The classic one in mine is the boot door alarm switch - if the bracket gets loose there's a continuous warning beep all the time I'm driving. Infuriating. The B&D tools have met most of my DIY needs so far, and I let the batteries discharge on a torch before recharging so they've lasted quite well.
     
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