# ZebraLight H501 runtime tests



## wapkil (Apr 26, 2009)

I have an impression that the information about ZebraLight H501s runtime behavior posted in the "Some ZebraLight H501 runtime graphs" thread is getting too fragmented and hard to read. It may be a good idea to gather everything in one place. I hope it is ok to start a new thread on the topic...



*Introduction*​
In this post the results of the runtime tests of ZebraLight H501 and H501w lights are discussed. The tests were conducted last week to see how the lights behave in different modes and with different battery types. I ran full runtime tests for the high and medium mode and for NiMh and LiIon batteries. In the low mode only a short brightness output level test was performed.

In the first section of the post the test setup is described. The second section shows the relative comparison of the lights brightness for different modes and battery chemistries. The next two sections discuss the high and medium mode tests results for NiMH and LiIon batteries. In the fifth section a brief comparison of the lights current and power consumption is given. The section six shows selected detailed graphs of the circuit regulation behavior. The final section provides preliminary conclusions drawn from the performed tests.



*1. Test Setup*​
I don't have a luxmeter so for my test I used a DMM measuring the short circuit current on a Vishay Semiconductors BPW21R photodiode. The diode has a built in correction filter to give an approximation of the spectral response of the human eye. Between 10^-2 and 10^5 lux it has a linear relation between the photocurrent and the illumination. The current is also largely independent of the temperature. The diode was put inside a 30mm long, 12mm wide white PVC pipe with an aluminum foil cylinder inside to reflect the light. The H501 was placed on the other side of the pipe.

The measurement results were recorded with the frequency of 5 data points approximately every 2 seconds (i.e. ~2.5 datapoint per second).

I believe this setup let me perform meaningful measurements. I cannot use it to determine the precise lux or lumen values (has anyone already checked them for H501?) but the relative values described below should be accurate.

In the NiMH tests I used Sanyo 2700 mAh NiMH batteries. I usually use Eneloops but this is the same battery ZebraLight used in their specifications. The batteries were charged on the Maha C-9000 and removed after the charger reported that charging is "done" (so there was no top off charging performed). My batteries measure only around 2500mAh on the Maha C-9000. The batteries were left to settle down for one or two hours before the usage.

In the LiIon tests the "Blue" TrustFire 14500 batteries (DX sku.3435) were used. They are rated 900mAh but I believe they are substantially less - I think around 700mAh. The LiIon batteries were charged with UltraFire WF-139 charger They were removed after the green diode indicated charging is complete and left for one or two hours to settle down.

When comparing NiMH and LiIon runtimes it's important to remember that the mAh "capacity" numbers are not directly comparable between different chemistries. A NiMH cell nominal voltage is 1.2V while for a LiIon cell it is 3.7V. Ideally it would be best to know how many Wh a battery under particular load holds. I don't know that. A close approximation is that for a Sanyo NiMh cell the number is 3Wh (~1.2V * 2.5Ah). If the TrustFire LiIon cell would really be 900mAh, it would hold approximately 3.3 Wh (~3.7V * 0.9Ah). I think in reality a TrustFire battery is probably closer to 650-750mAh so around 2.5Wh. It means that it probably holds around 10%-20% less energy than my Sanyo 2700 NiMHs.



*2. Output comparison*​
To compare relative brightness for different modes and different battery chemistries I ran a short test. The lights were turned on for 10 minutes in every mode and then the test was interrupted.

In this test the obtained values depend on the exact placement of the light head so the graph shows only an approximate relation. Nevertheless the results well approximate the lumen outputs given in the lights descriptions.

In this graph the 100% value represents the illumination given by the H501 in the high mode with a NiMH battery.





Fig. 1 H501 and H501w output comparison​

The low level outputs for the H501 on a LiIon battery and for H501w on a NiMH battery are too close (2.72% and 2.69% respectively) to be distinguishable on this plot.

In this test the obtained values depend on the exact placement of the light head so the graph shows only an approximate relation. Nevertheless for NiMH batteries the results well approximate the lumen outputs given in the lights descriptions.

Note that in the high mode with a LiIon battery the H501 offers only ~40% of the NiMH output. In the high mode the H501w is also around 10% dimmer than H501 (not really a noticeable difference). In the medium and low modes the differences between both lights and both chemistries are completely invisible.



*3. NiMH batteries*​
Two full length tests were performed for NiMH batteries. When the light approaches the end of a NiMH battery capacity it starts to flicker. When the flickering starts it is fast but delicate and almost invisible. After a while it starts to be more and more visible and annoying. I think it is not a built-in functionality but only a side effect of the way the circuit works. The flickering isn't present when LiIon batteries are used. When present the flickering can be used as an indicator that the battery starts to run out.


In the high mode without cooling the light becomes uncomfortably hot. During this test the H501 was placed in a fridge. This was the only test not performed in room temperature.






Fig. 2 H501 NiMH high mode test​

Please note that during the test the ambient temperature was 8 degrees centigrade. I think that in this temperature a NiMH battery can have lower (I guess between 5% and 15%) discharge capacity than in room temperature.

In the high mode the output is not strictly constant - it lowers slowly approaching 80% at the end of the runtime. I think this circuit behavior is the result of good design decisions. I like regulated lights but in the high mode I prefer them to give me, say, 2 hours of output with 80% light at the end than to give me constant 100% output at the cost of a much shorter runtime.


The medium mode test results were most important for me as I will be mainly using the lights in this mode. Chronologically this is also the first test that I performed.





Fig. 3 H501 NiMH medium mode test​

The runtime achieved is shorter than 19 hours promised by ZebraLight but the batteries are only 2500mAh and were not topped off. If they really were 2700mAh, the light could indeed run for 19 hours (as was shown in other reports). In this mode the circuit keeps the output almost constant.



*4. LiIon batteries*​
For LiIon batteries the high and medium runtime tests were also performed.


When LiIon battery is used in the high mode the output is lower and in room temperature the light doesn't noticeably heat.





Fig. 4 H501 LiIon high mode test​

In the high mode with LiIons the output is around 40% of the NiMH output but with more than 2.5 times longer runtime (311 min vs. 115 min, i.e. 270%). The light is similarly regulated for both the chemistries but at the very end of the LiIon test the output jumps to 207% of the initial brightness. It lasts with the brightness above 180% for around 16 seconds and then turns itself off.






Fig. 5 H501 LiIon medium mode test​

As you can see in the medium mode for Li-Ions the output is practically equal but the runtime is substantially lower than for NiMHs: 9 hours 41 minutes vs. 17 hours 18 minutes (i.e. only ~56%).



*5. Current and power consumption*​
I have measured the initial current taken from a fresh battery while trying to understand why the H501 behaves differently for different chemistries.


```
NiMH                            LiIon
        Current [mA]    ~Power [mW]     Current [mA]    ~Power [mW]
High    1150            1380            134             495.8
Med     160             192             71.9            266.03
Low     35.5            42.6            14.5            53.65
```

Table 1 H501 current and power consumption​

The measured current explains why in the high mode LiIons when compared to NiMHs give ~40% output and ~270% runtime. I still don't understand though why in the medium mode the light has similar output but with only around half the runtime.



*6. Additional plots*​
Two additional plots were prepared to show how the circuit fights to keep the light output constant. They are for a NiMH and a LiIon battery and both of them are for the medium mode. The plots are drown as a zoomed part of one of the respective graphs shown earlier.



​
Fig. 6 H501 NiMH medium mode test (zoomed)​

For the NiMH test the zoomed part presents the measurement results from the first 1038 minutes (when the output was approximately constant). The output is indeed practically constant - a few percent difference between the highest and the lowest illumination is completely invisible to the eye. I wonder whether fluctuations like this are normal for all the circuits.



​
Fig. 7 H501 LiIon medium mode test (zoomed)​

In the medium mode for LiIon batteries the output doesn't "jump" in the way similar to the medium mode for NiMHs. It gradually lowers from 100% to 96% few minutest before the end of runtime. Then it starts to act interestingly, as shown in the plot above.



*7. Conclusions*​
The measured NiMH runtimes are close to the ones specified by ZebraLight. In my tests they were slightly shorter than what is advertised but I believe that the capacity of my Sanyo 2700 batteries (measured 2500mAh instead of 2700mAh) are on the lower end of the spectrum.

The high and medium modes are nicely regulated. The output for both the chemistries (NiMH and LiIon) is practically constant for the medium mode and gradually dims to 80% at the end for the high mode.

The lights behave differently for different battery types. In the high mode LiIons offer less than half the output than NiMHs (~40%) but also more than 2.5 times the runtime (~270%). In this mode with a LiIon battery the light also doesn't heat up. I think this setup may sometimes be useful when twice the medium mode brightness is needed but for longer than NiMH high mode runtime.

In the medium mode for LiIon batteries the light seems to be really inefficient giving the same output as for NiMHs but only approximately half the runtime.

When a NiMH battery is used the light starts to flicker at the end of the runtime. This behavior is not present for LiIon cells.


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## wapkil (Apr 26, 2009)

Reserved for possible updates.


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## nzbazza (Apr 26, 2009)

Awesome Work!!!!

Runtime graphs are gold around here!!!!
:twothumbs :twothumbs :twothumbs :twothumbs


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## Flying Turtle (Apr 26, 2009)

Good job, wapkil. Thanks for putting it all together. Yes, we do love the runtime graphs.

Geoff


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## DM51 (Apr 27, 2009)

wapkil, you've done some excellent work on this for which members are very grateful, but it is actually more confusing now to have 2 very similar threads on the same subject. This is also cross-posting, which is prohibited by Rule 9. 

I suggest the solution will be to update post #1 of the original thread, by copying the text from here. I'm going to close this thread, but you should still be able to copy and paste everything across to the other one (using Ctrl+A, Ctrl+C, Ctrl+V). Please let me know by PM if you have a problem with that.


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## DM51 (Apr 28, 2009)

I'm re-opening this thread - the previous one has now been closed with a link to this one.


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## wapkil (May 22, 2009)

I was recently asked via PM about the H501 brightness with lithium and alkaline primaries. I thought others may also be interested so I'm copying my answer here:

I haven't tested the H501 runtime for primaries but before making runtime graphs I made some brightness tests with my camera here. I think that after a few minutes of usage with lithium batteries, the output would settle to the level identical with NiMHs. I don't use alkaline batteries but I suspect that the brightness should also be the same.

If someone has runtime graphs for primaries in the H501 please let us know


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## dudu84 (Jun 22, 2009)

Thanks very much for your great work, Wapkil. 
I can never imagine myself managing this kind of complicated analysis 

On a side note, I just finished a runtime on my H501w with eneloop (charged to 2040 [email protected] on La Crosse BC-900). I don't have a lux meter with me so I only measured the runtime until low battery warning kicked in.

Got 13h47', I pulled out the AA eneloop immediately when the light started flashing and its voltage was bouncing back from 0.97v. I guess the light works until voltage drops to ~0.95v. 

Compared to the claimed 19h on 2700mAh, I was short of ~35' which isn't a big deal when taking into accounts the variations in circuits and LED Vf and also batteries.


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## wapkil (Jun 23, 2009)

dudu84 said:


> Thanks very much for your great work, Wapkil.
> I can never imagine myself managing this kind of complicated analysis
> 
> On a side note, I just finished a runtime on my H501w with eneloop (charged to 2040 [email protected] on La Crosse BC-900). I don't have a lux meter with me so I only measured the runtime until low battery warning kicked in.
> ...



I'm glad you liked my runtime tests. They are nothing special, I only had to connect the DMM and wait until the battery is depleted. I saw oscilloscopes and spectrometers used in other reviews and wouldn't be surprised if someone X-rays the tested light bodies to check the durability :laughing:

I think the specification may be a little on an "optimistic" side for most of the H501s but close enough for me to also be satisfied with my lights.


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## Hugo2x (Oct 5, 2009)

Thank you for collecting this data, so many times manufacures distort runtimes vs. Output, it's good to see that zebralight is on the level


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## wquiles (Oct 5, 2009)

+1

Thanks much. I just ordered my own H501w last night :thumbsup:


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## Shorty66 (Oct 5, 2009)

Can anyone explain why the runtime and ragulation on a 14500 is s much worse than on normal AA batteries?

Thats something i would really like zebralight to improve...


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## ZebraLight (Oct 5, 2009)

The circuit in the H501 is a high effiency boost converter with some limited buck mode capabilities. 'Limited' in that it can handle higher voltages but with lower efficiency. Adding a full blown buck conversion (like we have in the H30 and H60, both with larger diameters) to the H501 will likely increase the length by about 2mm along with some added weight.


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## Shorty66 (Oct 5, 2009)

Speaking for myself, i would gladly carry that extra gram and the added 2mm wouldn`t bother me either.
The h501 is a darn small light and in my opinion it wouldnt hurt. Just remember that 14500 are lighter than AAs, too.
I understand, though, that only few users want to use 14500s. This might be partly because of the limited support on the h501 but mostly because normal AA batteries are easier to get.

If you would use a circuit like that on the h30/h60, shouldn`t you be able to make a turbo mode like on the h60, too? Perhaps with more limited runtime as the cooling isnt as efficient...

If you could integrate that, i think more people would use 14500s.

My ideal Zebralight would be like this:

Six modes in three groups like on the H60:
1lm/Slow Beacon Strobe (1hz or less)
10lm/30lm
100lm/Faster Strobe (4hz like on the h501r)

All values a bit brighter on 14500s with the same runtime.



Another thing which would make Zebralights a lot better would be an integrated headband. I made some Cad drawings on how this could work:





This is a new Battery Cap which also holds a Headband in Zipka-retractable style.
This design would be nice as it is completely integrated in the zebralights body and will easily slip into your pants pocket. 
Today we wont take the Headband with us if we EDC the zebralight. Thats sad as the zebralights really shine if used as headlamps. 
If you could EDC your headlamp it will come in handy quite often, i think.

I would really like to hear your thoughts on this one.


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## davidt1 (Oct 5, 2009)

In the mean time, a few simple and inexpensive mods have allowed me to enjoy EDCing my H501 in my shirt pocket for months now. 

The simplest and cheapest mod is to simply remove the clip from the light and the silicon holder from the headband and add an elastic band to the headband. The headband is now thin enough for pocket carry. 





I needed a small clip that does not have to be removed for headband use. The Fenix clip was an inexpensive $2 solution. 





The $2 clip and a $1.50 home-made headband keep everything thin and small. This thin clip does not have to be removed for headband use. Note the clip is attached to light while on the headband.





How thin and small? Enough for shirt pocket EDC.






Can't use it like this without a clip and being able to use it this way is why I like my H501 so much. How many headlamps can be used this way?






The solutions are there. I would love to see the throw increased by 50% though. That's just another 5 feet. How hard is it to do that?


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## werdnawee (Mar 6, 2010)

Hi, 

Great runtime test. An unbelievable amount of detail.

My question is more about operating the H60w for long periods.

Basically, I'm trekking a mountain in July and the summit stage is from 3am to 6am so a headlamp is required for about 2 hours.

The summit is 4,000m so should get to about 0 degrees celsius. (help with cooling?)

Anyway, I bought the H60w for this climb. Will it last for 2 hours without melting my head? 

Generally, what does overheating do? Chance of exploding or will it simply shut off?

Thanks


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## kramer5150 (Mar 6, 2010)

FWIW, my H501 did 85L OTF in bigchelis' sphere. see link in my sig.

:twothumbs


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## wapkil (Mar 6, 2010)

werdnawee said:


> Hi,
> 
> Great runtime test. An unbelievable amount of detail.
> 
> ...



You should ask someone who tested an H60 but I believe that in 0 deg. C it shouldn't have any problem cooling itself. I think though that it wouldn't want to run for 2 hours straight in the high mode. Doesn't it have a timer to switch to the lower mode after 10 minutes to prevent overheating?

Either way, you'd feel uncomfortable long before it approaches any dangerous temperature. If it overheats, it would be too hot to touch, let alone to keep it on your forehead.


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