I've found an Energizer Ultimate Lithium AAA cell's output voltage drops to an unusable state after a few minutes use and takes many hours to recover, whereas a regular alkaline battery seems to work fine in my single AAA cell LED flashlight.
I have a single-AAA cell Fenix LD01 I keep clipped to my pocket for the last three years. Having an EDC light like that has proven to be fantastic. It's so small and light I don't notice it, and yet provides up to 80 lumens whenever I need it, and it's always there. The light has proven to be rugged, the clip has worked very well (only failed once in three years), and I like how it can be squeezed on, or twist to stay on.
The problem I've had is I thought I was smart to load it with Energizer Ultimate Lithium batteries. I've only ever used these batteries. Because it only takes one, the higher cost is still quite reasonable. I wanted the cold weather performance, which is vital on winter nights. I was led to believe they might last longer too. Although I use my light perhaps a half-dozen to a dozen times a week, I usually only need a for a few seconds at a time. A single AAA lasts several months or more before I change it, often proactively to ensure it doesn't die at the wrong time.
However, I've found that if I use the light for several minutes and turn it off, it won't turn back on again, at least not immediately. In fact, it might take more than an hour before it turns on again. I considered the possibility of overheating. I found posts with other users describing the same, but the advice was to clean the contacts. My contacts are not the issue. Because of the small mass of the whole unit, it seemed unlikely that it would take hours for it to cool sufficiently. I also found that if I swapped the battery, it would turn on immediately, and so ruled out overheating or any kind of protection circuit.
Instead, I found that after just a few minutes of use, the I92 battery's voltage drops to .8V. It slowly creeps back up about 0.001 of a volt every ten to twenty seconds. After many hours or perhaps even the next day, it will rise back to 1.4V or more. The battery would almost certainly continue to provide sufficient voltage as long as I kept the light on, but as soon as I turn it off, the output voltage drops.
I suspect something is going on with the battery's internal resistance, but I don't pretend to understand it fully. If I put a new I92 in there, it will possibly last for up to an hour at 80 lumens (Fenix's claim), but if I turn it off after only a few minutes use, the output voltage will be too low until it apparently recovers. This isn't just one I92, or a batch of them. This has been going on for three years with many batteries over the years.
What is it that I don't understand about the I92? At this point, it seems greatly advantageous to switch to regular alkalines or possibly even NiMh for cold weather.
The damn thing failed me most recently caving. Obviously I wasn't depending on it for anything extreme, but after turning on my LD01 I had to exit the cave early, and when I wanted to re-enter, it wouldn't turn on. I had to explore the cave with the light of a phone screen. About a year ago it also failed me on a bike ride at night in a dark forest. I only needed enough light to keep me on the paved path, but made the mistake of turning it off for a moment and ended up getting along by will alone.
Now I know that both times it was not the Fenix, but the I92 that failed me, and a regular alkaline would not have.
I have a single-AAA cell Fenix LD01 I keep clipped to my pocket for the last three years. Having an EDC light like that has proven to be fantastic. It's so small and light I don't notice it, and yet provides up to 80 lumens whenever I need it, and it's always there. The light has proven to be rugged, the clip has worked very well (only failed once in three years), and I like how it can be squeezed on, or twist to stay on.
The problem I've had is I thought I was smart to load it with Energizer Ultimate Lithium batteries. I've only ever used these batteries. Because it only takes one, the higher cost is still quite reasonable. I wanted the cold weather performance, which is vital on winter nights. I was led to believe they might last longer too. Although I use my light perhaps a half-dozen to a dozen times a week, I usually only need a for a few seconds at a time. A single AAA lasts several months or more before I change it, often proactively to ensure it doesn't die at the wrong time.
However, I've found that if I use the light for several minutes and turn it off, it won't turn back on again, at least not immediately. In fact, it might take more than an hour before it turns on again. I considered the possibility of overheating. I found posts with other users describing the same, but the advice was to clean the contacts. My contacts are not the issue. Because of the small mass of the whole unit, it seemed unlikely that it would take hours for it to cool sufficiently. I also found that if I swapped the battery, it would turn on immediately, and so ruled out overheating or any kind of protection circuit.
Instead, I found that after just a few minutes of use, the I92 battery's voltage drops to .8V. It slowly creeps back up about 0.001 of a volt every ten to twenty seconds. After many hours or perhaps even the next day, it will rise back to 1.4V or more. The battery would almost certainly continue to provide sufficient voltage as long as I kept the light on, but as soon as I turn it off, the output voltage drops.
I suspect something is going on with the battery's internal resistance, but I don't pretend to understand it fully. If I put a new I92 in there, it will possibly last for up to an hour at 80 lumens (Fenix's claim), but if I turn it off after only a few minutes use, the output voltage will be too low until it apparently recovers. This isn't just one I92, or a batch of them. This has been going on for three years with many batteries over the years.
What is it that I don't understand about the I92? At this point, it seems greatly advantageous to switch to regular alkalines or possibly even NiMh for cold weather.
The damn thing failed me most recently caving. Obviously I wasn't depending on it for anything extreme, but after turning on my LD01 I had to exit the cave early, and when I wanted to re-enter, it wouldn't turn on. I had to explore the cave with the light of a phone screen. About a year ago it also failed me on a bike ride at night in a dark forest. I only needed enough light to keep me on the paved path, but made the mistake of turning it off for a moment and ended up getting along by will alone.
Now I know that both times it was not the Fenix, but the I92 that failed me, and a regular alkaline would not have.