Hack A Mag-Lite To Be Rechargeable


Most tools sport rechargeable batteries these days, but there’s no need to toss that old flashlight: just replace the cells with rechargable ones!

[monjnoux] had a 3-cell D-sized MagLite lying around—though you could reproduce this hack with a 2 to 5 cell model—which he emptied of its regular batteries and replaced with some 11000mAh NiMHs from eBay. The original bulb was also tossed in favor of a 140-lumens LED.

After disassembling the flashlight, [monjnoux] set about installing the new parts. He replaced the original bulb with the LED, soldering it into place and securing it with hot glue. He then drilled a hole in the body of the flashlight for a DC socket. The charger he purchased is adaptive, detecting the number of cells and adjusting its voltage accordingly. It had the wrong connector, though, so [monjnoux] simply chopped off the end and soldered on a new one. For a hack that comes in at 40€, it’s definitely a cheaper alternative to the official rechargeable model: which costs 80€. And with a duration of 7 hours (though it’s unclear whether this number reflects continuous use), it likely outlasts the official model, as well.

10 thoughts on “Hack A Mag-Lite To Be Rechargeable

  1. How about a 3-D printed bottom cap with contacts, and a charging stand, just like a cordless phone? You could also do this with those cheapo LED flashlights on ebay and dealextreme.

    The maglight isn’t waterproof anymore after this hack, so it’s lost one of its big advantages over the cheapies. I was flooded out once and I can tell you I was very glad to have a waterproof flashlight on hand.

  2. A quick round of calculations here:
    The batteries supposedly store 11Ah*1,2V*3=39.6Wh, while lasting 7 hours. That makes an average power consumption of about 5.66W. For a 140lm LED, that results in a total efficiency of just below 25lm/W, or about as much as an average halogen bulb.
    So either the batteries suck, the charger doesn’t charge them all the way or the LED’s electronics are highly inefficient. Either way, there’s something seriously wrong with this build.

    1. It’s a 3 cell version, so without a boost converter, there’s simply not enough voltage to get much brightness partway through the discharge. That would be a nice feature if it used lead acid batteries but NiMH and lithium batteries both like being in the middle.

    1. you’re entirely right guys! i had in mind to add a cap to have again the waterproof ability.
      and yes my calculations was wrong. with my charger, 2 days charge is need to exploit the 11000ma capacity.
      my first goal was just to reuse my old torch.

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