Rechargeable AA batteries.

BTW, I’m assuming these are all Ni Mh batteries and all have about the same amount of battery life before needing a re-charge.

Eneloop Pro rechargeables are the best, IMHO.  They seem to hold their charge longer than most other rechargeables.

I’ve used eneloop in my GPS.  Every couple years they start to not last as long before they need recharge, especially if it’s cold.

I’ve used other Nimh and didn’t think they have as much capacity as eneloop.

Another thing is that they slowly discharge even if I’m not using them.  I try to charge them within a week or two of using them.  Eneloop are supposed to be a little better.

I use Eneloop Pro rechargeables in my GPS and get 18 -19 hours of usable charge.

+2 on the Eneloops.    I rarely buy lithium anymore.  Just be sure to re-charge them– just prior to  your next trip.

+2 on the Eneloops too.  I use them everyday, so lithium would be really pricey.  I also have found that slower charging makes them last longer along with “refreshing” them every few months.  i like the La Crosse Technology BC700-CBP Alpha Power Battery Charger .  it refreshes the batteries as well as does a slow charge.

15 years ago I did a geeky study of the performance of flashlight batteries, and also that of the various types of bulbs. I kept track of run time of each flashlight/battery combination, at temperatures of 70* F (in the house) and also at temperatures of ~+32* F and 0* F on the patio. The batteries I tested were Duracell alkaline, Energizer Ni-MH rechargeables, and Energizer lithiums. I found that the Duracell alkalines petered out at about +32* F, the rechargeables at about +30* F, and the lithiums not at all even at temperatures down to 0* F.

The rechargeables worked best if I had charged them up the day of the test. They did have a significant loss of charge over 1-2 weeks (self-discharge). I assume that the technology of rechargeables has improved over the past 15 years, but I still rather doubt that they will perform well at much below freezing temperatures. My summer stint at McMurdo in Antarctica convinced me that the only battery worth using in severe cold was a lithium one.

https://visualsproducer.com/2016/03/31/panasonic-eneloop-pro-batteries-real-world-tests/

(low discharge, rated to -20 c)

If only someone would market lithium-ion pencells the same size as AA and AAA.  Thought they did, and bought a few batteries that turned out to be useless for AA and AAA applications.  Still one more reason to buy a Petzl Hybrid and use the Core battery pack that is basically three AAAs wired together in a package.  Probably electrical engineers on BPL will know more about this.

The nominal voltage of Li Ion is 3.6 v and that is why a AA or AAA sized version does not work on equipment designed to work at around 1.5v.

There is one brand that sell a 1.5v Li Ion rechargeable , called Kentli.

They have a circuit inside each cell to reduce the voltage.

My suggestion would be to check very carefully that they will work in your particular device.

” low discharge, rated to -20c”

Wow, Franco, the rechargeable technology has vastly improved since I did my testing 15 years ago! I might jump in on the Eneloop Pro cells, to try them out.  Trouble is, I’ve been stockpiling  Energizer AA and AAA lithium batteries for several years, and I might currently have a lifetime supply of them. I do like the fact that they are likely the lightest cell available, they have a great output, and they have a 20-year shelf life.