... since the A3 is a multi-mode light, AND it is risky to run unregulated (on high) for very long a light intended for 1.5V batteries with 3.7V batteries, you will generally be using the medium and low settings anyway. Every once in while you can switch to high and see if the battery is able to support full light output or not. If the light dims quickly after switching to high, then it is time to take out the drained battery.
Experts, let me know if that's faulty reasoning.
if you promise not to call me an expert :sigh:, i can tell you where stuff like that goes ary, even if i will Do it myself.
the driver is a boost, it has a max operating voltage of about 3-3.6v it can operate with a voltage (probably) down to .9-.7 , it keeps drawing MORE current as the voltage of the battery drops.
The moment you toss a 4.2V li-ion cell in you will slam overdrive the led into direct drive , minus a few bits and pieces of a curcuit thing that will be heating up internally.
When the voltage drops below the drive voltage of the LED it will finnaly go into regulation.
The led heats, is driven over spec (with this battery for very short times) making the led gates internally burn out a little, the battery gets heated by the led, the battery is pushed well beyond its specs , and it heats, and as you already know this could cause some issues.
on the other hand, the 10440 battery can barely output an overdrive for that led, depending on the battery quality resistance and state and all, it will just have a terrible time keeping up with any of it, so it doesnt stay bad for the led for long. the battery by default has to do a job it was not designed to do.
the battery heats, the led , the led heats the battery, the driver components heat, the others, and you have a vicious circle of cross heating, accidentally left on in the pocket, any one of the 3 things could burn out or fail. like a little Fizz pop, and the hot pants dance from the battery. the led getting low in output, and the driver failing or becomming inefficeint from carbonised components. I suppose the biggest safety issue, would be the battery going critical in pocket when driving 70MPH down freeway. which would be the same as a bee stinging your gonads while driving :mecry: maintain composure , pull off to the side of the road, then FREAK OUT
Further into the discharge of the battery:
eventually the voltage on the li-ion drops below the Vf of the led, and the current on the boost driver does the same thing it does to the poor alkaline, and starts trying to draw even more current off the battery.
the regulation tries to keep the led drive current going
the battery is waning down in voltage
the regulation still keeps sucking the battery harder and harder
the battery will eventually peter out still (as you indicated)
and the voltage of the li-ion cell could have been pulled as low as .7v
once the pulverisation is stopped (soon enough) the battery will recover some voltage, and rested again, look like it wasnt pulled down as hard as it was in the light.
because when the capacity of the battery is drained the output will tank ANYWAYS , if you pulled fast enough you will have only partly damaged the battery
the process of the battery being drawn on in higher currents as the voltage drops to do the boosting, will occur when the battery has the least ammount of capacity and ability to output that current.
Then Low or MED
If the light uses Current control, low or med will not overdrive the led, but as we already know it is a boost curcuit, with PWM.
So in med or low, the overdrive of the led will be going off in Pulses as opposed to continuous, but no less hard pulses that overdrive the led
the same pulses are also pulling more from the Battery then its design specs, so even though it is low or med, because it is pulsed averaging and not actual current control, both the battery and the led are still driven over spec.
the led when the battery is over the led voltage, and the battery the whole time.
on the other hand, the PWM pulsing does give the led and battery time to cool out, so the led has a chance to cool between pulses, and the same with the battery.
The battery voltage on ANY mode, could be drawn down well below specs , and will only show up this issue when it is at the total end of its capacity, WHICH if done correctlly (as you stated) will drop in voltage even more than the boost curcuit will be pulling it down in voltage, FINNALY, which should show up as a lowered light output.
WHEW, i hope i got that right.
ok with that said, i still do it :thinking: yup, but knowing that will all be happening.
