alkaline vs li-ion in flashlights?

[Brian321]

Are LI-ION AA batteries going to last longer or be brighter than alkalines? i am going caving tomorrow and cant decide if its worth the extra money for li-ion's. Sorry if this has been covered but i couldnt find it.

 

[Black Rose]

They would be brighter, assuming the light/headlamp you are using them in can handle the almost 3x increase in voltage (alkaline cells are 1.5v, 14500 cells top off at 4.2v).

Capacity-wise, 14500 cells have less capacity than their alkaline equivlents.

For what you are looking to do, I'd recommend getting some Energizer Lithium (L91) AA primary cells instead.

 

[pfccypret]

In my experience the energrizer lithium AAs do last longer. But I don't think long enough to justify the cost. But might be a decent investment if you want to carry fewer batteries and change them less often.

 

[LED_Thrift]

I've done some caving and IMHO it's not a great time to experiment with lights. Li-ion cells are, as Black Rose mentioned, about 3x the voltage as alkalines and most lights can't handle that increase in voltage. Lithium primaries [Energizer L91's] are a great replacement for alkalines in high power lights, but cost a lot more if you buy them in a store.

I use rechargeable NiMH's in my AA lights with great results. They can deliver more amps in high powered lights than alkaline, are very good in cold temperatures like lithium, and are rechargeable. I prefer the low-self-discharge cells such as Eneloops or RayOVac Hybrids.

 

[andrewnewman]

I second the suggestion for Energizer Lithium (L91) AA primaries. Caving represents one of the most mission-critical uses of a flashlight outside of military, search and rescue and law enforcement. Please PLEASE consider carrying spare fresh batteries and several flashlights in good working order. Flashlights should be water tight and able to withstand a drop without failing. I also recommend that at least one light be tethered to an article of clothing so that it can't fall too far if you drop it. Headlamps are also of enormous value when caving.

Sorry for diverging from your original query a bit.

 

[PeaceOfMind]

Definitely get some energizer lithium AA's if you're going tomorrow. I have a feeling you might have meant lithium rather than li-ion, since if it's tomorrow you won't have much chance to actually order in any li-ion rechargeables and they're hard to find locally.

Lithium AA's (which are not rechargeable) are a great replacement for alkalines. Lithium batteries have more capacity, perform better under load, perform better at extreme temperatures and are much lighter than alkaline. In general it's a fantastic battery chemistry.

 

[Brian321]

Definitely get some energizer lithium AA's if you're going tomorrow. I have a feeling you might have meant lithium rather than li-ion, since if it's tomorrow you won't have much chance to actually order in any li-ion rechargeables and they're hard to find locally.

Lithium AA's (which are not rechargeable) are a great replacement for alkalines. Lithium batteries have more capacity, perform better under load, perform better at extreme temperatures and are much lighter than alkaline. In general it's a fantastic battery chemistry.

Yea i did mean lithium rather than li-ion, sorry guys. Well i guess i will pick up some energizer lithiums then.

 

[vali]

Keep in mind if you are using a 3xAAA direct-drive headlamp you can fry the leds because lithium cells have higher votage and less internal resistance.

If you have a regulated flashlight/headlamp, then you will probably be safe.

 

[Kestrel]

Another vote for Eneloop NiMH's.

Their reputation for consistency and overall reliability is tops here on CPF. I think I'd carry Eneloops for main (rechargeable) usage along with the highly-regarded Energizer lithium AA's as backup spares. I don't really know of any cell combination that would be as reliable as these two in conjunction.

Keep in mind if you are using a 3xAAA direct-drive headlamp you can fry the leds because lithium cells have higher votage and less internal resistance.

Hmm, there might possibly be an issue with the slightly higher voltage of the Energizer AA lithiums, I can't say for sure. However, not too long ago I read a reasonably authoritative post here (sorry I can't recall from who) who posted internal resistance measurements for various AA cells, and for whatever reason NiMH was half that of alkaline or Energizer lithium AA's (which were comparable).

(That topic was on how fast an AA-powered electronic flash can cycle and it turned out that it had the fastest cycle time from the low-internal-resistance NiMH cells, and took approximately twice as long to charge the capacitors & 'cycle' using the higher resistance alkalines or the Energizer lithiums (although the lithiums naturally provided much more overall usage).

Edit: Thinking about it some more, I believe I have seen Energizer ship one of their 3xAAA LED lights (direct driven) with AAA Lithiums, so maybe they figure it's OK. :shrug:

 

[yellow]

skip all those AAs and switch to 18650s.
just 1/3 of loose batteries to care for, each cell houses 1.5 times the power than the equivalent three AAs, light is smaller, system cost (cells, charger) cheaper, ...

I did that some 3 years ago and never feel disappointed.


PS: one time use cells (Alkaline, Lithium) have NOTHING to do inside caves. How much I hate those ppl that throw away them ... the same as those idiots that "dispose" away their unused carbide there.
With rechargeable cells most anyone feels "pressurized" to bring them home to recharge and use again - that alone makes them 1st choice for regular use.