H51w getting warm fast on highest setting?

[elbowtko]

Hello,

After much lurking around this forums I have come to buy my first "higher end" flashlight and have settled on the H51w. I have a few questions regarding this flashlight.

Checking out the highest setting for even a few moments (2-5min) I realize it got noticeably warm (but usable) and perhaps if I left it for long enough I feel it could become too hot for me to touch. This has not happened while on the other settings only at the max. It is warm throughout the whole flashlight body including the battery when I take it out.

The battery I am using is an energizer alkaline battery. I am afraid it might be prone to leakage after an extended period of time, are they designed to take the heat? Are lithium batteries recommended or eneloops instead?

Thanks

[LightWalker]

A light that small running at almost 200 lumens is going to generate heat, you should not run it on max without holding it in your hand to act as a heatsink.

Discharging an alkaline battery that quickly may cause it to leak and get stuck in the light, lithiums or Eneloops would be ideal.

[eh4]

I consider the H51's top output to be of less use than H2, which is only slightly less bright unless you really need the extra light to punch a little further. H2 won't heat up and lasts 2.5X longer while appearing nearly as bright.
Personally I find L1, M1 and M2 to be the most practical, as well as being the brightest levels per run time, very useful light levels.
H1 is just "what's the most light possible?" level, not the most effective level in most cases.

[bbb74]

+1 re using H2 instead of H1. The visible difference isn't much but the heat difference is a fair bit.

[Helmut.G]

It's completely normal for the light to get hot. The highest setting is an extremely high output, low runtime setting for a 1xAA light.

[Cataract]

I've used mine on high till the level dropped to low MANY times. Yes, it gets warm quick and hot enough so you don't want to hold it tight, but it won't cause burns. I use NiMh batteries and no problems. I've done it with an alkaline once or twice too, but I didn't leave it in afterwards just to be on the safe side.

[Helmut.G]

I've used mine on high till the level dropped to low MANY times. Yes, it gets warm quick and hot enough so you don't want to hold it tight, but it won't cause burns. I use NiMh batteries and no problems. I've done it with an alkaline once or twice too, but I didn't leave it in afterwards just to be on the safe side.

How did the runtime compare?

[Cataract]

How did the runtime compare?

Not comparable. About 30 minutes on the alkie to low and close to 50 minutes before step down on the NiMh. My only gripe with Zebra are the short runtimes.

[Helmut.G]

Not comparable. About 30 minutes on the alkie to low and close to 50 minutes before step down on the NiMh. My only gripe with Zebra are the short runtimes.

The problem is lights using 1xAA to drive a high power LED are always inefficient (compared to 2xAA, for example) because the input voltage is very low.
The Zebralight has an extraordinarily high output in this class of flashlight, short runtimes on max are the price.

I'm actually a bit surprised that the difference between Alkaline and NiMH is so small.

[Cataract]

The problem is lights using 1xAA to drive a high power LED are always inefficient (compared to 2xAA, for example) because the input voltage is very low.
The Zebralight has an extraordinarily high output in this class of flashlight, short runtimes on max are the price.

I'm actually a bit surprised that the difference between Alkaline and NiMH is so small.

I don't really care about the runtime on alkalines and I agree that one AA alkie can't give you that much, but I do believe that we should get more than 40-50 minutes of runtime on one NiMh (don't forget that the runtimes and outputs are almost the same as with a CR/RCR123 Zebras and I get a solid 2 hours at 180 lumens on my PD20 in comparison).

The difference between alkie and NiMh isn't all that small; we're talking about more than twice the runtime: 30 minutes to LOW on the alkie and 45-50 minutes to MEDIUM on the NiMh, so I could have kept running the NiMh for a little while to have an exact comparison, possibly another half hour.

[Helmut.G]

I do believe that we should get more than 40-50 minutes of runtime on one NiMh.

some manufacturers' claims:
Fenix LD10 .... 100 lumens max (110 minutes)
Fenxi LD12 .... 115 lumens max (130 minutes)
Quark AA ...... 109 lumens max (72 minutes)
Quark mini AA .. 90 lumens max (78 minutes)
ZL H51 ......... 200 lumens max (54 minutes)

In my opinion Zebralight's numbers are pretty amazing as are the LD12's.

edit: even though I suspect those 200 lumens are a bit overrated.

[Cataract]

some manufacturers' claims:
Fenix LD10 .... 100 lumens max (110 minutes)
Fenxi LD12 .... 115 lumens max (130 minutes)
Quark AA ...... 109 lumens max (72 minutes)
Quark mini AA .. 90 lumens max (78 minutes)
ZL H51 ......... 200 lumens max (54 minutes)

In my opinion Zebralight's numbers are pretty amazing as are the LD12's.

edit: even though I suspect those 200 lumens are a bit overrated.

They do look good on paper but, as you said, the output seems a little overrated. To be honest, I don't know exactly what is the FL1 criteria for runtime (until next mode or 50% output) but I definitely don't get 50 minutes at full output. I know I ask a lot, but my main problem with this is the almost imperceptible difference in output / runtime from a H51 compared to a H31 while I get more (perceived) output and runtime on my PD20. I'm sure Zebralight will get better runtimes as they further develop their drivers, I'd just like to see it now so I don't have to buy the same lights again in a year or two...

[bbb74]

They do look good on paper but, as you said, the output seems a little overrated. To be honest, I don't know exactly what is the FL1 criteria for runtime (until next mode or 50% output) but I definitely don't get 50 minutes at full output. I know I ask a lot, but my main problem with this is the almost imperceptible difference in output / runtime from a H51 compared to a H31 while I get more (perceived) output and runtime on my PD20. I'm sure Zebralight will get better runtimes as they further develop their drivers, I'd just like to see it now so I don't have to buy the same lights again in a year or two...

My test with a fairly new fully charged eneloop was my sc51w ran in H1 for 43 minutes before suddenly dropping out of regulation. It then faded over the next while (10 minutes or so). Probably would have gone longer in a low mode but didn't bother.

This is pretty good when you compare it to, say an LD20 R4 which got ~96 minutes out of 2 eneloops with a fairly similar output (if you consider that the cool white zebras have the same current draw but just put out more light than the less efficient neutral leds). The discharge rate on a single AA zebralight reduces the effective capacity somewhat vs a lower discharge rate on a 2xAA light. Also the Quark AA2 Turbo ran in turbo for 88 minutes, the LD25 for 90 minutes, with similar-ish output and 2xAA's which had to work much less hard.

[Cataract]

My test with a fairly new fully charged eneloop was my sc51w ran in H1 for 43 minutes before suddenly dropping out of regulation. It then faded over the next while (10 minutes or so). Probably would have gone longer in a low mode but didn't bother.

This is pretty good when you compare it to, say an LD20 R4 which got ~96 minutes out of 2 eneloops with a fairly similar output (if you consider that the cool white zebras have the same current draw but just put out more light than the less efficient neutral leds). The discharge rate on a single AA zebralight reduces the effective capacity somewhat vs a lower discharge rate on a 2xAA light. Also the Quark AA2 Turbo ran in turbo for 88 minutes, the LD25 for 90 minutes, with similar-ish output and 2xAA's which had to work much less hard.

Your test with the Sc51W seems exactly like the runtimes I get, but...

My L2D R5 ran for a solid 1H50 - 2 hours on turbo last time I checked and the batteries weren't 100% new, which is pretty much exactly what Fenix has it rated for. I'm sure the Quark AA^2 turbo should also get more than that as it is rated for at least 2 hour runtime at max output and my Quarks do get a solid 2 hour runtime on 2XAA. But potatoes to potatoes; as an example on how the runtimes can get better, the V11R is rated at 1.5 hours with an output of 190 lumens on an AA battery (I haven't tested this yet, however, but I can say the 25 minute runtime at 500 lumens is right on).

I know 1 AA can only give so much juice, but my main problem is the lack of difference in output / runtime between the AA and CR123 models. It makes buying the AA models a much more interesting choice, but right now I need a new hiking headlamp and might have to settle for a measly H600W with an output of 361 lumens if I want a runtime of at least 2 hours on high... (well, the 232 lumens for 4 hours kinda sounds like what I'm really looking for).

And by now we're severly off-track from the thread's main subject

[LightWalker]

Your test with the Sc51W seems exactly like the runtimes I get, but...

My L2D R5 ran for a solid 1H50 - 2 hours on turbo last time I checked and the batteries weren't 100% new, which is pretty much exactly what Fenix has it rated for. I'm sure the Quark AA^2 turbo should also get more than that as it is rated for at least 2 hour runtime at max output and my Quarks do get a solid 2 hour runtime on 2XAA. But potatoes to potatoes; as an example on how the runtimes can get better, the V11R is rated at 1.5 hours with an output of 190 lumens on an AA battery (I haven't tested this yet, however, but I can say the 25 minute runtime at 500 lumens is right on).

Quark AAx2

Max	205 OTF lumens for 1.3 hours

[Cataract]

Quark AAx2

Max	205 OTF lumens for 1.3 hours

My bad, the R5 is stated at 1.2 hours. I was only looking at the last part I guess

[LightWalker]

Is the Fenix L2D R5 ANSI rated?

[Cataract]

Is the Fenix L2D R5 ANSI rated?

Don't know why I put R5, my L2D is a Q5, so not ANSI rated, but the output does compare with my SC51W (haven't tried ceiling bounce comparison, though) and the runtime IS 1H50-2H on NiMh batteries as I have tested it multiple times. Newer models (LD22) state 2H26, but we are talking about 2 AA and not single AA here...

[LightWalker]

Don't know why I put R5, my L2D is a Q5, so not ANSI rated, but the output does compare with my SC51W (haven't tried ceiling bounce comparison, though) and the runtime IS 1H50-2H on NiMh batteries as I have tested it multiple times. Newer models (LD22) state 2H26, but we are talking about 2 AA and not single AA here...

The performance and runtimes of the Zebralights is impressive.

[Cataract]

The performance and runtimes of the Zebralights is impressive.

On a single AA yes, although their runtimes are a little overstated. On single CR / RCR 123's no. That's all I'm trying to say here.