Q5 in a 1AA

[Gaffle]

I do not know a ton about LED Vf. I have read a few posts where people thought the high Vf of a Q5 would make it not so suitable for a 1AA light. I was checking out the new L2D-CE with the Q5 (due on Oct. 24th), and I thought how nifty it would be to purchase the L2D(Q5) and then get the L1D body.

I have just a basic knowledge of Vf in LEDs and what it does. I just want to know how bad a Q5 with a higher Vf would really be in a 1AA. Would runtime be way low? Would a higher Vf beat up a single NiMH?

Pleased to help understand me!!:candle:

 

[Sgt. LED]

Well you'll get less output at the start, and a shorter runtime too. I think the cell would be feeling the burn alright.
I don't know how but I'll bet there's a way to do it with a booster, this is CPF after all! $$ though......

 

[yellow]

Please, stay serious guys:
at a given current the difference between the more recent Cree, Seoul, Rebel is next to not noticeable.

As to 1 AA --> to have any led run on high power (=1 A) the board must be able to grab 3.5 A from the cell
... now think how long any batt. would give this current - even if drivers doing this were more common

 

[Steve L]

The only way I see driving a Q5 at 1 amp with a VF ~3.7-4.0 is with a 14500.

 

[Gunner12]

One way is to use a good NiMh AA battery, a RV7 board and a Cree Q5. The board has been measured at 1.1 amp to the LED, over 200 lumen at the LED.

 

[Bullzeyebill]

I think that a Cree Q5 run by an AA that has a semi-regulated boost circuit would be good. Run the Q5 at about 150-200 mA's to the led. That would be nice and bright, and not a terrible strain on the poor little AA.

Bill

 

[LightScene]

The Olight T15 (1 x AA) is supposed to be available with a Q5 any time now from batteryjunction. It will also handle a 14500.

 

[AzN1337c0d3r]

I don't think it would be too bad. Modern NiMH AAs have capacities of 2500 mAH and are quite capable of sustaining a 1C (2.5 amp) discharge rate all the way down to 1V for about an hour according to this energizer datasheet (http://data.energizer.com/PDFs/nh15-2500.pdf)

Since we need to step this 1.5V up to 3.7V (which is roughly 2.5 times give or take), to get 1 A @ 3.7V, we'll need ~2.5 amps @ 1.5V feeding the transformer.

Not that bad of a load for NiMH chemistries... but the battery life sucks.

 

[Nitroz]

I am working on a gerber infinty with a cree led powered by one 14500 lithium and one of Kaidomain cheap boards.

 

[richdsu]

In this scenario, running 1AA draws up a lot of current, the battery gets hotter faster than your led emitter.

Hot battery is not good and dangerous, you have no way of channeling the heat off the battery except to shut off the circuit.:sick2:

 

[Gaffle]

I have not been able to find a good data sheet with the Cree Vf. I am in the "self teaching" electronics mode. So far it seems that the Rebel has a lower Vf than the Cree. If that is the case a L2D RB100 + L1D body sounds nice.