Unscientific testing of the Zebralight battery checker function

So I had a couple spare hours yesterday and some batteries that needed charging so I decided I'd run them down a little more for the sake of my own curiosity.

The battery checking feature in Zebralights is something I find pretty handy, but the question is how much battery do I really have left? Also, is it reliable? No one else may find this of much value, but I decided to test both my SC62w (Keeppower 3400 mAh protected) and SC52w (ZL brand Sanyo 840 mAh protected) to see what the voltage threshold is for 1-4 flashes. After a lot of clicking and unscrewing and screwing battery caps to check voltage repeatedly, these were my results.

SC62w
3 flashes start at 3.94v
2 flashes start at 3.71v
1 flash starts at 3.53v

SC52w
3 flashes start at 3.96v
2 flashes start at 3.82v
1 flash starts at 3.71v

It was interesting that the SC52w was that much different. I assume this is because it's known that 14500 has much less capacity than 18650 so ZL decided to give us more of a warning to find a charger soon. Could definitely be wrong here though.

The SC52w exhibited some odd behavior when 1 flash was reached. Turbo would come on for about one second then immediately drop to medium. Even after doing this several times and resting voltage after several minutes was below 3.7V, all of a sudden the light started performing as normal with turbo coming on for one minute before it's regular step-down. This lasted several cycles until turbo would last maybe 20 seconds before dropping to medium. In other words, when you're down to 1 flash, you'll be limited to medium and below.

I didn't have time to check the SC52w with a standard Eneloop, but one straight out of the package at 1.32v yields 2 flashes, and I had another one that was at 1.20v that yielded 1 flash. Charged that one before I went to bed and checked it with at least an 8 hour resting voltage of 1.42v that yielded 4 flashes. With 1 flash, it will come on in a lower high mode and double clicking to a higher high yields no change.

Again, this probably is of no use to most, and it may vary between different lights of the same model or might even vary with different batteries, but I tend to find little things like this interesting and interested to hear if others rely on this function much.

My sc32w comes on H1 and stays on H1 despite 1 flash with primary. I've come to the conclusion the voltage meter isn't accurate with primaries.

Thanks very much for reporting this information. I am wondering if the same battery in the same flashlight will yield the same results if performed more than once. But it is understandable that you may not want to endure another episode of what you went through to get this information, and I also question just how accurate your test results are (please take no offense).

I use the flash check regularly and find it to be sufficient but would prefer a little more precise method in the 3.7-3.8 volt range where I like to recharge the battery: very small quibble. I use my SC62d nightly and many days as well.

Thanks Again

On my SC52's and SC5, I don't find the battery flashes to be much use on Eneloops. 1 or 2 flashes means the battery is low, and that's fairly accurate, but 4 flashes can mean just about anything it seems. It might be full, or it might be half-empty.

Sometimes when I try the battery test, it seems pretty accurate. But then I can try it another time and it seems useless. I think you have to let the flashlight sit for a couple of hours, to achieve a good resting voltage, to get any useful result at all.

Perhaps lithium-ion is better at settling to a resting voltage than NiMH cells are, which is why the battery indicator is better on lithium-ions.

Yeah, I'm no Eneloop expert and don't use them in my SC52w except as backup, but with Eneloops do you ever really have a fully charged battery, and what is considered full charge? They come off the charger at over 1.5V and soon rest to right above 1.4V like I stated above. I have a spare I carry with me that I fully charged at least a month ago and it now sits at 1.33V, basically the voltage you get with one ripe from the package.

The battery gurus might know, but when you take one fresh off the charger and put a load on it, is there a rapid drop to 1.32V, which appears to be full resting voltage, then it sort of levels out? But when I put it on my D4 charger at 1.32V, it gives a capacity of 2 out of 5 bars and my SC52w gives 2 flashes, neither signifying full capacity.

I will say on lithium ion, they do rebound fairly quickly after the light is off and while checking voltage I'd have to scramble to get the battery back in while double checking all of these numbers because the thresholds for the flashing levels were quite sensitive and very consistent. So you can use the light, turn it off while the battery is at 3.93V, and immediately check the battery and it'll show 3 flashes, but wait about 2 minutes while it rebounds and it'll show 4 flashes. I have some Keeppower 16650 2600 mAh that are actually 4.35V batteries that I'm only capable of charging to 4.2V, and I'd be interested to see if it acts differently.

KITROBASKIN said:

Thanks very much for reporting this information. I am wondering if the same battery in the same flashlight will yield the same results if performed more than once. But it is understandable that you may not want to endure another episode of what you went through to get this information, and I also question just how accurate your test results are (please take no offense).

I use the flash check regularly and find it to be sufficient but would prefer a little more precise method in the 3.7-3.8 volt range where I like to recharge the battery: very small quibble. I use my SC62d nightly and many days as well.

Thanks Again

Click to expand...

I can tell you my sc32w might show 4 flashes a day after showing one flash despite not being used in the interim. It just isn't accurate. The battery was a surefire primary at exactly 3 volts which should be 2 flashes imo.

I sure wish they used a meter like Nitecore - 3 flashes, pause, 7 flashes = 3.7v. Simple and fairly accurate. Of course it takes longer to sit there and count flashes, but it's worth it IMO.

I'm consistently on 1 flash with my primary now so do I toss it or drain it dry? Hmm

markr6 said:

I sure wish they used a meter like Nitecore - 3 flashes, pause, 7 flashes = 3.7v. Simple and fairly accurate. Of course it takes longer to sit there and count flashes, but it's worth it IMO.

Click to expand...

Yes, so do I. Takes the guess work out of it. With using lithium ion though, I feel like the ZL way works ok.

Thanks uofaengr, just more evidence that checking capacity on nihms, by voltage, is dubious at best, while checking voltage to determine capacity on Li-ion is a fairly stable endeavor.

recDNA said:

I'm consistently on 1 flash with my primary now so do I toss it or drain it dry? Hmm

Click to expand...

Yes.




Just kidding. I would think that checking capacity on lithium primaries, using voltage checks, would be a fairly accurate process. I don't use that particular battery chemistry, so I don't have any anecdotal evidence either way.

I am assuming that Zebralight is checking capacity, on the different battery types, via voltage checks.

Trouble is the battery is still over 3 volts. There is no zero flash response so 1 flash should be the voltage at which high drops right to medium for lack of power. At over 3 volts H1 works fine and stays on indefinitely. 1 flash should be somewhere below 3 volts imo.

recDNA said:

Trouble is the battery is still over 3 volts. There is no zero flash response so 1 flash should be the voltage at which high drops right to medium for lack of power. At over 3 volts H1 works fine and stays on indefinitely. 1 flash should be somewhere below 3 volts imo.

Click to expand...

Maybe because Zebralight is assuming you're running with higher voltage RCR123's in the light? It probably can't tell the difference between drained RCR123's, and full CR123 primaries.

In the SC52, it can tell the difference between 14500's and NiMH, but that's because the voltages never overlap.

WalkIntoTheLight said:

Maybe because Zebralight is assuming you're running with higher voltage RCR123's in the light? It probably can't tell the difference between drained RCR123's, and full CR123 primaries.

In the SC52, it can tell the difference between 14500's and NiMH, but that's because the voltages never overlap.

Click to expand...

If so that is really poor engineering. Doesn't make sense though because 3.2 volt fresh CR123A's give 4 flashes

recDNA said:

If so that is really poor engineering. Doesn't make sense though because 3.2 volt fresh CR123A's give 4 flashes

Click to expand...

Oh, well. Anyway, like I said, I don't much trust their battery charge indicator anyway. Use a DMM and estimate for yourself. Or a ZTS tester to get a much more accurate measurement. Or, if you use rechargeables, just charge them up!

I do..but it would be such a great feature if it only worked

Anybody know how many amps it pulls from primary on H1

recDNA said:

Anybody know how many amps it pulls from primary on H1

Click to expand...

Most lights use about 5 watts at around 500 lumens. So, probably around 1.5 amps for 480 lumens, give or take. Measure it at the tailcap with your DMM and see.

WalkIntoTheLight said:

Most lights use about 5 watts at around 500 lumens. So, probably around 1.5 amps for 480 lumens, give or take. Measure it at the tailcap with your DMM and see.

Click to expand...

1.5 amps at 3 volts? Too much for primary battery - especially with voltage sag.

I just measured it at 2 amps! The thing is I do not trust the reading because I went to H2 and only measured .3 amps. I then went back to H1 and it measured 1.54 amps. Surefire CR123A at 2.975 volts. I'm afraid to use H1 now. That is to much current for a primary only rated at 1 amp continuous draw. No wonder the battery gets so hot. If the initial 2 amp reading was correct that is WAY too much power for a primary.

recDNA said:

1.5 amps at 3 volts? Too much for primary battery - especially with voltage sag.

I just measured it at 2 amps! The thing is I do not trust the reading because I went to H2 and only measured .3 amps. I then went back to H1 and it measured 1.54 amps. Surefire CR123A at 2.975 volts. I'm afraid to use H1 now. That is to much current for a primary only rated at 1 amp continuous draw. No wonder the battery gets so hot. If the initial 2 amp reading was correct that is WAY too much power for a primary.

Click to expand...

Yeah, high-output lights are really meant to be run off rechargeables. If you stick to H2 and lower, the primary is probably fine and will give you much longer run-times. Use H1 sparingly.

Kind of like trying to run the SC5 on H1 from a lithium primary (or god-forbid, an alkaline). It's really designed for NiMH.

P.S. I've noticed that Zebralights tend to be difficult to measure current accurately. Not sure why. Perhaps there's an initial higher start-up current, which drops down after the electronics settle. BTW, if you use the highest amp-setting on your DMM (usually limited to 10 amps), it will give the lowest resistance and most accurate measurement (it's something like 0.02 ohms). Only use the milliamp or microamp settings on low-current settings.

WalkIntoTheLight said:

Yeah, high-output lights are really meant to be run off rechargeables. If you stick to H2 and lower, the primary is probably fine and will give you much longer run-times. Use H1 sparingly.

Kind of like trying to run the SC5 on H1 from a lithium primary (or god-forbid, an alkaline). It's really designed for NiMH.

P.S. I've noticed that Zebralights tend to be difficult to measure current accurately. Not sure why. Perhaps there's an initial higher start-up current, which drops down after the electronics settle. BTW, if you use the highest amp-setting on your DMM (usually limited to 10 amps), it will give the lowest resistance and most accurate measurement (it's something like 0.02 ohms). Only use the milliamp or microamp settings on low-current settings.

Click to expand...

I have a fluke 73. It automatically adjusts. It has a 10 amp max fuse. I don't choose range but I do hold the probes in place with my fingers so connection not the best. I should get probes with clips.

Zebralight clearly says for CR123A as well as RCR123 but I have put in a ticket asking them about safety of primaries in H1. I believe the Surefire battery also has a protection circuit.

uofaengr said:

SC62w
3 flashes start at 3.94v
2 flashes start at 3.71v
1 flash starts at 3.53v

SC52w
3 flashes start at 3.96v
2 flashes start at 3.82v
1 flash starts at 3.71v

Click to expand...

Bump for an ancient thread...the closest I could find to my question. Apologies if this info is out there somewhere else...

Has anyone done a similar study on a Zebralight AA light?