NiMH cells are not so fragile as the slightest over discharge kills them. If you believe so, I think we have found the reason you don't think overcharge kills them... You are blaming premature death on other (incorrect) reasons. If moon mode "only lasts a few seconds", the light does not have moon mode.
I stated reverse charge, when there is more than one in series. If moon mode only lasts a few seconds it could be what I described, you are again ignoring simple facts like the one that we are discussing cells already drained so low that there is the discussion about whether a shutdown circuit would kick in, or perhaps you are assuming I meant a very high shutdown threshold without that being stated.
On a nearly weekly basis I find myself in situations where a sudden shutoff without warning can be VERY dangerous, and everyone else in my group finds themselves in the same situation. It is the nature of caving. Sometimes a single missed step can be fatal, and you can be in places where you physically cannot reach any other light.
Warning #1: Light output already dropped.
Warning #2: If you put a shutdown circuit in you can also put a low voltage warning indicator in IF it is that important to you, or of course carry extra cells, or of course know your equipment so you aren't wondering how much runtime you have remaining.
Then there's the issue of whether it is really reasonable to depend on a single AA NiMH light, which is what you seem to be implying you would depend on for caving. Is that
really what you use, or are you just trying to argue?
Boost lights with protection circuits will show no warning signs. Without protection circuits, the light will dim near discharge, giving you ample time to adjust. I get the feeling you have never used a boost protected Li-Ion light.
Most boost circuits will drop in light output before you'd need to implement a shutdown circuit, we're not talking about the ideals of optimal voltage here, just to mitigate the chances of cell reversal, at a point where there was practically no runtime left. You want to argue the extra few moments matter but ultimately the light is running out of power either way, if you couldn't plan for it running out a few moments ago you're still in the same boat, and let's face it if you had some cricitical caving "step" you couldn't miss, then is not the time to find the light shut off from normal mode and you, as you imply, can't reach to switch it to moonlight mode, because of some strange impossible scenario.
Further, by the time the light has dropped enough that you would like to switch to moonlight mode, it probably won't even turn back on since turn-on voltage can be higher than that needed to keep running - when it didn't hence making you realize the cell voltage had dropped.
Or, if you did have an indication because it got dimmer then we are back to what I wrote above, you already knew your time was limited either way, either way you are stuck soon enough because you underestimated the needed runtime, but being practical I think either of us would have a spare light or at least cells to use.
See above. Cordless tools are most often destroyed by improper charging practices than anything else. By far the most common cause of premature death is overcharge....
This generalization you are making is not applicable to cordless tools nearly as much as some other lower current consumer gear. What ends up happening is the user tries to get that last screw driven, last hole drilled, last 2 x 4 cut, and puts massive current through a fully discharged cell. This is easily reproducible, take any typical NiCd or NiMH cordless drill and test it yourself.
By merely refraining from such cell abuse - no changes in charging, packs last quite a bit longer. This was plainly evident and shown true, I don't think you appreciate how much current goes through a stalled or nearly so DC tool motor.
But if you actually served active duty, you should know that having front line equipment which is DESIGNED to cut off with absolutely ZERO warning is COMPLETELY UNACCEPTABLE. The same goes for law enforcement.
You are responsible for your gear, you cannot just wonder if your flashlight has enough charge for your patrol, shift, etc., and cannot go without a backup pack or recharge means if it's possible continual runtime would require it. If you can't find a way to have any warning, then it sure seems like you above everyone else need to carry a second light.
Think about this another way. With your ideal, it is quite conceivable the light drains till by the time you realize you need to switch to moon mode, it is too late and the light can't switch off/on into moon mode because the cell voltage is now too low (if, again a situation I disagree with, you are depending on a single NiMH cell light for something important as a regular carry light source).
Now consider the opposite. If a protection circuit shuts it off, the slight voltage depression it had from running at a higher power output recovered for a moment and you are more likely able to put it in moon mode.
So basically, it could be the opposite of what you suggest. Without a shutdown circuit once the battery is drained low enough you would notice there is nothing you can do to keep it running, while with a shutdown circuit there is a posibility you can get more light by turning it back on in a lower mode.
If you don't want to damage your cells, take them out when you notice dimming and recharge at the first available opportunity and you will avoid any damage. Frequent monitoring and top off charges (need that smart charger with the correct rate....) will avoid any damage from over discharge.
Of course, but remember I was writing about more than one in series. With your idea of no protection, it may be too late to get more light OR avoid running one of them below 0V into reverse charge.
But overall, you totally miss the point that protection circuits are NOT designed to protect the equipment, but rather protect the user. If you are not using volitile chemistries (Li-Ion, LiPo, etc), they are unecessary.
I missed no point at all, you assumed I somehow *needed* to feel there is only one possible benefit to a protection circuit. As for unnecessary, that's a long twisted road to go down. I deem it unnecessary to go caving without any idea of your battery pack can run long enough, and unnecessary to try and decide for someone else what they should or shouldn't have in a flashlight they buy.
However, it indeed is not necessary, nor are a lot of things if taken one at a time and discounted without considering there was a reason someone else subjectively chose them.
And remember, initially I wrote tools, you wrote flashlights and went off on some very unlikely caving tangent, one with no real hope if it's that hairy because in moonlight mode we could play devil's advocate and suggest you'd fall on the next step anyway due to low light, if it's really so treacherous you can't even reach into a pack and get another battery.
