Reddit reviews ENERGIZER L92 ULTIMATE LITHIUM 4 AAA ON CARD

> I'm also impressed that they support using a lithium battery without hurting the light (maybe that's a function of the newer LEDs?).

All AAA lights that I know of can run on a disposable lithium AAA like the Energizer L92. They're meant to be voltage-compatible with alkalines and only start off a tenth of a volt or so higher. As those are expensive and non-rechargeable, I would generally only recommend them for emergency devices which are stored for a long time and rarely used. Their shelf life and capacity are excellent, but NiMH rechargeables are preferable for daily use.

The D25aaa can also use 10440 lithium-ion rechargeable batteries, which are 4.2 volts at full charge instead of the 1.5 volts of an alkaline. The total energy stored in these is about the same as an NiMH AAA, but the higher voltage allows for greater light output in exchange for shorter runtime. Some lights are 3-4 times as bright when using this battery. Some lights are fully-functional with these. Some work, but can't access lower modes. Some are damaged by the higher voltage.

The LED has little to do with it. Most LEDs used in flashlights want 3-4 volts for the amount of current the driver circuit provides. It's the driver sensitive to extra voltage. Lights using a single 1.5 volt battery have a boost driver that increases the voltage to the amount the LED needs, regulates current and provides a means of controlling brightness, either by changing the current limit or blinking the LED rapidly. On some of these, an electronic component, usually the microcontroller can't handle too much voltage. On others, the driver simply doesn't handle the situation where input voltage is greater than the desired output voltage very well.

Lights intended for higher voltage battery configurations often have very different driver circuits that output less voltage than the battery supplies, or that don't change the voltage at all. Some have sophisticated circuits that can handle several different situations comfortably.

Eveready 1212 (aaa carbon zinc super heavy duty, 4 pack, 9 bucks) are typically 7.4 grams.

The Energizer L92 (aaa lithium battery, 4 pack, 9 bucks) has a typical weight of 7.6g, and here's an 8 pack for 12 bucks. The L91 (aa battery) weighs 14.5 grams.

^(It also keeps going and going and going and ...)

I've replaced the battery twice, once before starting the JMT and another time before a motorcycle tour up to Alaska. I've never seen the battery life indicator come up and I'd always use it in 5 minute tracking. I don't actually know how long the battery last, but if I'd have to guess, about a year with heavy use. You have to use lithium AAA's though. They maintain their voltage for the life of the device.

>Though, won't help me much against the griz and lions, but maybe if I break something lol...

Ha! I hear you. I was on a bike when I encountered a grizzly and her cubs and totally felt safe. The mountain lion was on a trail and staring right at me. That was actually actually concerning. The tracking is nice just in case they needed to find the body. I typically have people look at the tracking page sporadically and they know what to do if they see I haven't moved for too long.