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Dremel Micro Repair/Reuse

Recently at the end of 2016, I acquired a Dremel Micro cordless rotary tool from a garage sale/yard sale for about $20. I used it maybe 3 - 4 times until it didn't want to hold a charge for long. Basically when I put it on the charger, the LEDs scroll top/down indicating it is charging but after a minute or two they stop their normal scrolling sequence and they all stay lit up, which isn't even mentioned of in the manual. The fuel gauge battery indicator shows up red meaning it's near its battery life. At this point, I'm considering either to salvage the motor or buy a new battery for the dremel (which are 2 Sanyo 14650 batteries that are soldered onto a circuit board inside). I'm just wondering is there something that I have failed to do that would make the dremel not hold a charge?

Thanks in advance!

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I would put my bet on the batteries.
Once could be dead or with a faulty protection circuit.
A good charger will stop charging once it senses this problem.
Replace them with new batteries and you should be fine.
Keep in mind these things don't really like to be sitting unused in a shed for months.
Maybe it was just waiting for you to fix it so you have more fun together? ;)

TXVisual (author)  Downunder35m5 days ago

Well I acquired a lithium ion battery charger from Nitecore that managed to charge the batteries completely (based on the LEDs on said charger), so it might be a faulty protection circuit or something. I'll have to acquire a multimeter soon so that I can verify that the batteries have been charged. And yeah, I understand they don't like to be sitting unused for awhile, which I never have done but maybe the previous owner had been doing that. Thanks for the reply!

You can buy a cheap multimeter from eBay. I've found that the ~$5 ones work well for these applications.

If they've been sitting unused for a while charge them in an area where they won't damage anything if they catch fire. It's possible that they will, though it has never happened to me, and I've charged 15 year old 18650s that hadn't been used for years without an issue - they still work like new for my flashlight ⁽ᵒᶠ ᶜᵒᵘʳˢᵉ ᵃ ᶜʰᵉᵃᵖ ᵒᶰᵉ ᶠʳᵒᵐ ᵉᴮᵃʸ ᶦᶠ ʸᵒᵘ ʰᵃᵈᶰ'ᵗ ᵍᵘᵉˢˢᵉᵈ ᵃᶫʳᵉᵃᵈʸ⁾!

Maybe replace the dead batteries with bigger ones (just make sure they're the same voltage!)

TXVisual (author)  Yonatan245 days ago

That's what I was thinking, however I'd like to be able to re-assemble the Dremel Micro back together with the outer casing fitting properly. And after some research, the specific 14650 batteries are hard to come by as they've been discontinued and even harder to find with the tabs already on them. I can find a few bulk sales of them, but I don't wish to spend $1000+ for them. If worse comes to worse, I'll probably go with the bigger batteries and somehow have them fit on the outside of the casing.

Thanks for the reply!

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p...

I'd go with 18650 batteries from an old laptop or from eBay (don't buy the cheap ones). The last option would be to power it with a power supply...

Toga_Dan6 days ago

can u run it with it plugged into the charger?

TXVisual (author)  Toga_Dan5 days ago

I cannot as the charger is one of those stand-up/base chargers that charges through contact of metal pins both inside the dremel and inside the chargers' base.

connect wires between the base and the tool. If the batteries are truly useless, pull em out and recycle em at Home Depot, Best Buy, etc.