Battery help needed

Discussion in 'Functional Gear & Equipment' started by GrayGhost, Nov 3, 2018.

  1. GrayGhost

    GrayGhost Monkey++

    I have half a dozen 18v Dewalt ni-cad battery packs that are in need of repair/replacement. At ~$55 or so a piece, I'd rather not replace.

    I thought there was a thread or post(s) about rebuilding these, but am unable to it. It may have been by @azrancher, possibly.

    Any help or advice would be appreciated!
    Gator 45/70 and sec_monkey like this.
  2. SB21

    SB21 Monkey+++

    This is weird . I was just looking on youtube because i have some ryobi batteries that wont charge . Look on Youtube and you might find what you need . There is some tricks in there that is worth trying before you spend money on them . Im fixing to try them myself . Let me know if any of them work for you .
  3. oil pan 4

    oil pan 4 Monkey+++

    Yes you should be able to get some raw nicad or NiMH cells and replace them for a few $ each.
  4. sec_monkey

    sec_monkey SM Security Administrator

    NiCad batteries stink

    Get NiMH as @oil pan 4 suggested or better yet get the official Li Ion upgrade kit which allows the old tools to use new Lithium batteries, they werk a lot better :) :)

    [chopper] [chopper]
    3cyl, GrayGhost, john316 and 2 others like this.
  5. sec_monkey

    sec_monkey SM Security Administrator

  6. UncleMorgan

    UncleMorgan I eat vegetables. My friends are not vegetables.

    Another gag you might consider:

    Empty a defective battery of everything except the contacts (which will have wires running to the + and - of the battery stack).

    Drill a hole in the empty battery and run a nice long lamp cord into it. Secure it with knots close against each side of the hole. Attach the cord to the wires inside the battery. Keep track of their polarity.

    Cut the plug off the lamp cord (Don't even THINK about plugging it in. Trust me on that.You will not like what happens if you do.)

    Separate the strands on the cut end and then either:
    1. Hook them up to a wall-wart of the right voltage that puts out enough amps. Make sure you get the polarities correct.
    2. Hook the wires to a exterior battery pack. If you need 18V, for example, hook up three (preferably rechargeable) 6V lantern batteries.

    Wall-wart gives you power forever. Good if you work inside.
    A battery pack can be worn on the belt, or just set down where you're working. It's portable.
    GrayGhost, Gator 45/70 and sec_monkey like this.
  7. duane

    duane Monkey+++

    Have tried 2 of the DW lion converters to 18 V to replace old 18 V batteries with limited success. The converters use a switch like arrangement to drop the voltages and it will not work in all tools as some require more current than it will put out, a dead short can destroy the switch, the batteries supplied are neither their best nor do they have the most capacity, and it doesn't include a charger. It is useful as I have several old 18 volt tools that still run well. The local battery store rebuilds nicad batteries using new cells and while they work well and last, they are not cheap. I have been replacing my old DW tools with Hitachi lion ones for about what it would cost for new DW batteries, picked up a new warranty and have had good luck with their tools so far.. YMMV
    GrayGhost, sec_monkey and Gator 45/70 like this.
  8. Gator 45/70

    Gator 45/70 Monkey+++

    The ''Newer'' Ryobi battery's will not charge in the older style charger no matter what the sales person say's,
    If you go new get the newer charger and save some gas, Been there,Done that hahaha
  9. SB21

    SB21 Monkey+++

    Its the newer Lithium Ion ones . I've just got one battery that wont charge , its almost new . I saw on the tube that if they get below charge at a certain level , they wont take a charge . They say you've got to kind of jump start them , throw a little juice to them , I guess so the charger will read them . That's my understanding anyway . I'll try out the theory 1st chance I get .
    GrayGhost and Gator 45/70 like this.
  10. duane

    duane Monkey+++

    Most if not all Lion batteries have a protective circuit built into them so that they will not easily blow up or catch fire under adverse conditions. That same circuit will keep the battery from taking a charge if the proper voltage and amperage isn't supplied, in addition, as you may have noticed the shapes and pins differ on many of the batteries of the same voltage and the charger will either not allow the battery to be inserted if not the right shape, nor energize without the right pins.

    Millwaukie batteries used to be bad that way. Charger would not start a charge unless there was about 9 v on a 12 v battery. Used to take a pair of alligator clips with a 5 ohm resistor in one leg and connect it to a good battery for about 10 min to put a surface charge on it and then place in charger at once. Often would charge up again and be usable, but never as good as new.
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  11. SB21

    SB21 Monkey+++

    In my case , This is one of the batteries that came with the charger .
    Gator 45/70 and duane like this.
  12. duane

    duane Monkey+++

    Not real uncommon to have brand new batteries bad, defect in cell, defect on electrical circuit, bad spot welding of connectors to cell to create series for battery. Don't fight it, if new, just get another under warranty. Play with it and you either void warranty, or have it kind of work until it fails and is out of warranty. It is in your best interest to do that with any new power tool. All the companies do their best to slip out if they can and often make you jump thru hoops just hoping you will solve their problem by giving up.
    SB21 and Gator 45/70 like this.
  13. GrayGhost

    GrayGhost Monkey++

    It's not a matter of charging for me, now. If they go below a minimum voltage, the circuitry will not allow a charge. I've used my battery charger (car) on jump mode to put enough voltage into the battery to get the charger to start.

    Hope that helps....bunch of YT videos on this as well.

    Edit to add: I've only done this with ni-cads...and it works.

    I keep one in the Jeep with this mod... 15' cord with alligator clips.

    Has anyone had good luck with a particular replacement battery? Decent price?

    I have some Li-ion tools, and they are way better. That said, the Dewalt units have lasted for 12 years, then gave up the ghost. Pretty good ROI, if you ask me.
    Last edited by a moderator: Nov 3, 2018
    Witch Doctor 01, Gator 45/70 and SB21 like this.
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