I think you are overestimating the dangers of lithium ion. I mean, you don’t see people dying in droves by exploding cell phones right? And those are 3.7 volt, 3000mAh batteries, about the same as an 18650. As long as you are reasonably careful, you should have no issues, barring some design flaw.
The problem with 1xAAs is that they aren’t really bright enough in comparison. With only 1.2 volts to work with, and fairly limited current draw, its difficult to get enough gas to get a lot of light out of such a small light using NiMH. Granted, they have come a long ways…zebralights are pretty amazing what they do with 1xAA. But still, they are quite pricey.
For just a little bit more size an 18650 has way better power density, and much higher current draw capability and a more useful 3.7 nominal voltage.
You can also get a smaller 16340 or 18350 type light that is a bit shorter but similar power.
Curious, Where? bad reputation as in negative reviews?… or something more serious, like severely over-charging NiMH cells? The latter condition can happen when you charge 2 cells in series that do not have exactly the same actual capacity.
FWIW… you can over-charge a NiMH battery and it can vent gasses. Venting expanding gasses trapped inside a water-tight enclosure is a recipe for an explosive condition. Once the gas pressure exceeds the containment limits of the device. The difference is NiMH does not vent caustic, flammable gasses.
I have an old nimh dumb charger that charges the cells in series configuration… and it just… works… but I dont know if that would be good for batteries. Specially for lsd.
However… I always charge eneloops with smart chargers (dV and dT termination)
The niteye is tempting me despite it os nor 100% what I am searching for…. oh no! Another flashlight for my collection?? XP
4xAA, micro-USB charging and Nichias sounds like the perfect allround flashlight for muggles. I’m sure some flashaholics would like it too, me for example.
BLF AA rechargeable flashlight
+1 on a BLF project for a USB rechargeable AA flashlight, with 1, 2 or 4 batteries. Although us here probably won't either need or want this, it see it as a great item either as a gift to people unaware of potential Li-Ion issues (overcharging, accident, ...) or more simply to be used by children going on a holiday camp or anything similar. In other words taking no risk at all with the batteries/flashlight ...
Hank's 4 AA rechargeable flashlight
Hank, looking at the page your flashlight points too, I don't see any plug or info about battery recharge within the flashlight. Or what did I miss? https://www.dorcy.com/190-lumen-led-flashlight-yellow
Existing single AA rechargeable flashlights
Now, although there seem to have been, in the past, a few single AA flashlights that could be recharged through an USB port, manufacturers don't seem to produce them anymore. And as much as as AA batteries in serial may present quite an obvious electrical issue for recharging, I'm not sure why it should be such an issue for a single AA - cost put apart. Talking about cost, now that we have very decent rechargeable 18650 flashights under $20 (best example, amongst others : Eagle Eye X2R), I'm not sure how cost would be an issue anymore. And given that micro usb chargers and cables are now widely used, thanks to smartphones, interest seem to be obvious, at least to me ...
So, is anybody aware of an existing, decent and price effective (in short: BLF friendly ) single AA rechargeable flashlight?
I think, as others have pointed out, the charging circuit for NiMH is more complex than for lithium-ion. I tend to be paranoid about lithium-ion safety, but in a single-cell format, they should be very safe, especially with good quality cells. Of course they’re used in just about every kind of rechargeable electronics nowadays.
So, I’m not sure there’s really a market for USB rechargeable NiMH flashlights. You can pack almost as much energy into a single 18650 as 4 NiMH cells, and a USB charging circuit is simple and cheap for an 18650.
As much as I like NiMH flashlights, I’d go with a single lithium-ion format if I want built-in recharging.
Otherwise, invest in a basic Eneloop+charger kit, and keep some spares charged for replacement when needed.
Just a note for those who don’t know: No, you can’t pack anywhere near as much energy into a 18650 as 4 NiMH cells. A good quality NiMH cell packs around twice the mAh at around 1/3 the voltage as a good quality Li-ion of the same size. So, one NiMH cell is 2/3 as powerful as an equivalent size Li-Ion cell. Maybe you were talking about max current draw? Li-Ion does have a definite advantage there. But, a single High-capacity (not high-current) Li-Ion could still lose to 4x Eneloop NiMH in some cases.
Looking at HKJ tests, an Eneloop Pro (2450 mAh), at 1A discharge rate has an energy of 2,982 Wh.
A Sanyo NCR18650GA cell (3500 mAh), at 1A discharge rate has energy of 11,850 Wh.
So yes, a single 18650 can have roughly the same energy as 4 NiMH cells.
Alright, I did get crossed up a bit, but not in the way you think. You’re right, an 18650 Li-Ion does pretty well versus 4xAA NiMH. But, your math isn’t quite right still. The highest capacity Eneloop AA is 2450mAh. So your compare should look like this:
A single 18650 does beat 4xAA Eneloop. Sorry for my confusion. I was somehow thinking about size equivalence when doing my math before. :person_facepalming:
Yeah, I didn’t mean to say that your process was wrong, just the result (due to the difference in cells). I really just didn’t want to be the only one that was wrong.
But, the 2450mAh was exactly the one I was thinking of when I first made my assertion, so in the context of this conversation, it’s not debatable (because I don’t want to be too wrong).
Yes, I’m being a bit of a stinker today. But we’re still friends, right? :innocent:
We are absolutely friends Mr. David. :partying_face: And trust me, I make mistakes so often it hurts… The only stupid mistake I refuse to make at this moment is to blindly buy the 32000 lumen Imalent DX80, which is verrrrry attractively priced at $220,-. No sir, I WILL wait for some reviews, hehe… (and probably end up not buying)…
Yes, but they could go higher in multi-emitter designs. Zebralight manages to get 500 lumens out of a single AA Eneloop. With 4xAA, and the higher voltage allowing for a more efficient circuit, 2000 lumens should be easy.
But probably not much more. Even Eneloops tend to cap out at about 5 amps. They can go more, but performance really starts to drop. So, 20-25 watts is probably as much as you can realistically get out of 4 Eneloops. Whereas, a single high-discharge 18650 can give at least 15 amps continuous, or over 50 watts.
I don’t think I’d want to discharge a single 18650 at 50 watts, but supposedly it’s safe according to Samsung.
) single AA rechargeable flashlight?
