The perfect batteries

As part of putting together my 72 hour kit, I had to pick a flashlight, radio, and other electronics. To keep things simple, I decided everything should use the same kind of battery. I decided to go with the ubiquitous AA. It is fairly easy to find electronics that take AA batteries, and even if something needs the bigger D cells, I can buy a reusable adapter that can be stored inside of the device. But which brand of batteries and which model should I get?

After quite a bit of research I settled on the Energizer Ultimate Lithium battery. These little guys aren’t cheap (I paid $1.76 per battery) but they have several perks for use in a 72 hour kit:

1. Long shelf life. These batteries have up to a 15 year shelf life. Wow! That is double the life of a normal alkaline battery. I still plan on rotating every couple years.
2. Works in extreme temperatures. With an operating range of -40 F to 140 F, there isn’t any fear of being without power just because it is too cold or too hot outside.
3. Weighs less. Ultimate Lithium batteries weigh 1/3 less than alkaline batteries. This means you can carry weigh more (haha) without breaking your back.
4. Lasts longer. Although both types of batteries are rated at about the same mAh, you’ll get to use your radio and walkie talkies significantly longer with Ultimate Lithium than with alkaline. This is because alkaline batteries are unable to handle heavy loads or cold temperatures every well. Based on my research, Ultimate Lithiums will last 3-4 times as long as alkalines in normal everyday use.
5. Leak resistant. I absolutely hate it when I open a battery compartment and find nasty sticky goo and lots of corrosion. These batteries are designed to be virtually leak proof if used before the expiration date.

Sounds great, right? Well there are a few cons that you should be aware of before you run off and drop $100 on fancy batteries:

1. Consistent voltage. These batteries will stay above 1.4V until nearly dead. This has several implications. Battery gauges aren’t likely to be accurate unless your device was designed for lithium batteries, and low battery alerts become “your battery is going to die any moment” alerts.
2. Sudden death. These batteries die very abruptly. For example, if you use alkalines in a flashlight then the light will start bright then get dimmer and dimmer until it stops working. With lithium batteries it will start bright, stay bright, and then turn off. You get very little warning, so make sure you have backups handy.

These may not sound like huge cons, but they make these batteries unsuitable for things like smoke detectors where you want it to chirp at you for several days before the battery dies. These also aren’t replacements for rechargeable batteries that you would use for everyday use in things like cameras. For that use case you would of course want to use Sanyo Eneloop NiMH batteries.