can or can't you use rechargable batteries in a mini-mag : LUSENET : TimeBomb 2000 (Y2000) Preparation Forum : One Thread

I remember reading somewhere that you can't use rechargable batteries in maglites. I tried some and they didn't work. Anybody know if this is true for all maglites, I used a big 3 D flashlight? If so, why and are there any other brand as good as maglites that can use rechargable batteries.

thanks tomas

-- tomas (, December 10, 1999


I use NiCd rechargeables in my 3-'D' MagLites all the time. As long as you check the batteries occasionally and discharge them completely before recharging, they work nicely. But do check the batteries often, which applies ro all battery types, including alkalines which have a habit of reversing polarity internally and rupturing. Battery blood is exceptionally corrosive to circuitry.

O d d O n e

-- OddOne (, December 10, 1999.

Theproblem is not with maglite. Flashlight bulbs like all incandescant bulbs have some real limitations. They must get enough current to heat the filament to the proper temperature to create white or near white light. Too little voltage, red or yellow light because the filament is too cold. Too much voltage, greatly shortened life ecause the filament actually boils apart. 3 nicad cells gives you 3.6 volts. 3 alkaline cells gives you approximately 4.5 volts. Power goes up by the square of the voltage or current. 3.6 squared is about 13 while 4.5 squared is over 20. For the 3 cell flashlight to be useable with both types of cells, the bulb has to be designed to handle roughly a 50% difference in power. The manufacturer can correctly assume that most customers will use alkaline or cheap batteries, so the design is weighted in the favor of 4.5 volts. The bulb will be somewhat marginal at 3.6 volts, tending to yellow and orange because it is running too cool. This same bulb will run very bright with 4 nicads at 4.8 volts, only 14% high. Of course a 14% over voltage will result in at least a 30% and maybe much greater decrease in bulb life (poof), which is less than 50 hours for almost all flashlight bulbs to begin with. Many flashlight bulbs are rated for only 10 hours.

(Actually the picture is slightly better than painted because of the non-linear resistance of an incandescant bulb, but not very much better.)

The LONG term solution? Get a LED bulb replacement designed for the voltage that you will actually use. The brightness will be less than a regular bulb, but it will outlast over 1000 regular bulbs. If brightness is paramount, put a larger LED array (more LEDS in parallel) in the flashlight. (If you can get away with much less light, a single white LED running off of 1 set of 2 alkaline D cells will last a good 6 months non-stop. Dim. Really. See up to 15 feet away...)

-- tree (, December 10, 1999.

Another technique on the Maglite issue (doesn't work for mini's) is to buy some 4-cell bulbs to put in a 5 cell flashlight. You MUST use NiCads in this, so mark the barrel of the light with tape or something. The 5 NiCads put out about the same voltage as 4 Alkies, so it should be fine

-- hutch (, December 10, 1999.

We use nicads in our D-cell maglights, 2 cell size, with the standard bulbs, with no problems. Have been doing this for 10+ years. We use the heaviest duty (largest capacity in amp-hours) nicads available from Radio Shack. I used to use AA-nicads in my mini-mag light (2 cell size) but found that I didn't use the flashlight enough and the batteries self-discharged faster than I used the light. However, we are now also using some 3-cell lights with LEDs, and the light I use every night when I check the chicken coop, bring in the dog, etc., was last charged in August. (uses 3 d-cell nicads)


-- Jim (, December 10, 1999.

Three-diode LED flashlight bulb replacements are available at, last 11 years, battery life 300 hours, NiCads are fine.

-- Old Git (, December 10, 1999.

Have used nicads in 2 AA Mini-mags with the stock bulb and they work just fine. I've noticed the bulbs last a lot longer than they do if you used alkalines, probably due to the reduced voltage. Light is quite sufficient though. Personally am using 1100mah Panasonic Nicads.

-- Don Kulha (, December 10, 1999.

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