Vehicle Flashlights and Battery Choices

Before I go any further, let me state that the following is based upon my experience, my research, and the region I live in, the Upper Midwest. The temperature extremes here can run from -20’s F in winter to +90’s F in summer. Ambient temperature greatly affects battery performance and life, some battery types more than others. Inside a vehicle in summer, which is parked in direct sunlight, the temperature can reach +40º F, or more, higher than the outside temperature. That’s hot. OK, you get the idea, now on with the show...

My daughter has my old 2-D cell Maglite with an LED emitter upgrade stored in her van. Apparently, she has alkaline batteries in it and, it seems, it always needs new batteries, which she forgets to replace (hey, we’ve all been there). Plus, with alkaline cells there’s the potential for leakage and if you don’t catch that the light is ruined (been there a few times myself). Years ago, what I started doing was storing the alkaline cells outside the light, in baggies, but I digress.

From the research I've done, it seems the best option for a flashlight, or any battery operated device, which will be stored in a vehicle all year, are lithium primary cells (Energizer, to my knowledge, are the best). On their website, Energizer states: “they are complete with leak resistance and performance in extreme temperatures (-40ºF to 140ºF or -40ºC to 60ºC).” Their shelf life is incredible as well. See attached document.

The cheapest fix I came up with for my daughter’s vehicle flashlight is to put six Energizer lithium AA cells into two AA to D cell parallel adapters (ref pic below). I have both batteries and adapters, so there’s nothing to buy. Problem solved. As for her house JIC flashlights, I advised her to use Energizer alkaline cells, which is what we do. I check all our in-service batteries, say twice a year, for power and, if alkaline batteries are used, leakage signs. Google calendar helps me to remember to do this and a lot of other stuff.

 

AA to D cell parallel adapters

As for general battery application, a rule of thumb I use is:

• Alkaline primary cells - If they're hardly used and are stored inside; i.e. JIC flashlights.
• Lithium primary cells - If they're hardly (or lightly) used and are stored outside, i.e. vehicle JIC flashlights, garage door opener remotes and keypads.
• NiMH or Li-ion secondary cells - If they're used frequently and are stored inside (for the most part); i.e. daily use flashlights, headlamps, and radios.

That’s pretty much how I do it, based upon my climate, and if anyone has some ideas I’d love to hear them. There’s some variations and, of course, your mileage may vary.

Here's an Energizer manual on the subject for your perusal: Cylindrical Primary Lithium Handbook and Application Manual

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Take care and stay safe,

Joe Doakes aka Kilogulf59
Integrated Close Combat Forum

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