The search for the USB rechargeable AA flashlight

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.

Huh?

NiMH (AA Eneloop): 2000 mAh * 1.2V * 4 pieces = 9600 mJ
NCR18650GA: 3500 mAh * 3.6V * 1 piece = 12600 mJ

So a single 18650 cell has more energy than 4 Eneloops me think… I think you reversed the capacity of NiMH and lithium ion.

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.

http://lygte-info.dk/review/batteries2012/Eneloop%20AA%20BK-3HCC%202450mAh%20(Black)%20UK.html
http://lygte-info.dk/review/batteries2012/Sanyo%20NCR18650GA%203500mAh%20(Red)%20UK.html

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:

NiMH (AA Eneloop): 2450 mAh * 1.2V * 4 pieces = 11760 mJ
NCR18650GA: 3500 mAh * 3.6V * 1 piece = 12600 mJ

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, you’re right. Sorry. My explanation is above.

The math is right. The inserted value for capacity is debatable. I only use white Eneloops.

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. :smiley:

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). :wink:

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)…

:smiley: :+1:

there is a reason AA powered lights are not more than 1000 lumens per 4 batteries usually

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. :open_mouth:

Fair assessment.

So, if it weren’t for BLF, how many single 18650 lights would there be that produce over 1000 lumens?

My opinion - it would be the same number as 4xAA lights over 1000 lumens.

So, the reason, it seems to me is simply: Demand. We provide demand. The manufacturers then provide supply. :wink:

After Note 7, I somehow don’t trust Samsung when it comes to batteries… :frowning:

The Note 7 fiasco had nothing to do with the batteries. It was due to bad design of the body.

Yeah, I know.
But a company that lets something like that slip through can’t really be trusted.
On the other hand: after this they probably will watch themselves.

I would be happy with a 2xaa nimh rechargeable via usb capable of about 350 lumens or more.

There is the niteye ec-a12… but expensive….

God, please… hear me!!!

Does anyone know of charger ic’s that support both 1.5 and 3.7v charging and with minimal external components? I am very close to a generic 16mm charger board for 3.7v. With the option of attached micro USB or wiring a remote socket. I would like to start on a design for aa if I can find a circuit to follow.

I remember seeing the Jetbeam SRA40 ages ago but that thing is almost 4 years old today. It cost a ton too.

Maybe open up a multi-voltage capable charger and see what chip they use? I’d be interested in your design when you get it finished - if you’re sharing. :innocent:

It seems this is a relatively old thread, but maybe it will help the OP. If you are ok with 1xAA flashlight, there is the Jetbeam E10R. It can recharge both 14500 and Ni-MH AA. The user interface is not the best, but it is a competent light anyway.