trouble with a zebralight runtime

Hey guys
I dont think I've ever posted before, but I lurk frequently. I recently purchased a zebralight sc600 ii l2. This also required I purchase my first 18650 batteries, charger, and a multimeter. I wound up with 4 Panasonic 3400 mah batteries off amazon and a nitecore charger. All of my batteries are coming off the charger at 4.20 to 4.21 volts, and run fine at first, which leads to my problem.
None of the batteries seem able to run the flashlight on high after they discharge to 4.08 and below. The light will flash on h1 briefly and then won't go above m1. It will still strobe on high, but that's it.
This doesn't seem to give me very much usable runtime. I'm wondering if this is normal and I'm expecting too much, or possibly the batteries I selected cant supply the necessary current once the voltage drops? The lights battery indicator is giving me 3 flashes still.
If anyone can give me some advice here I would appreciate it, I'm slightly out of my depth with this jump to rechargables . Also if I should have put this in a specific sub forum I apologize, I didn't see anywhere specific this would fit.
Thanks
Kevin

:welcome:

Different batteries act different. Although that's pretty much a useless statement, batteries normally give a different voltage output under load than with an open measurement. It's likely that your cells have a bigger voltage dip under load, causing the Zebralight to step down. A bit surprising though, as the Panasonic cells tend to be regarded as some of the best cells in this class.
Perhaps this is more of an issue of how long it takes your batteries to run from 4.21V to 4.08V. You should try to do a measurement under load and see how the numbers are then.

Fwiw: 4.08V should indicate a battery capacity of around 90% (see here: http://www.powerstream.com/lithuim-ion-charge-voltage.htm), so either your batteries behave poorly under load, which would be odd considering the brand and the fact that 4 of them have this behavior, your Zebralight does or your multimeter is off - which would also be unlikely as the 4.21V measurement seems spot on for a battery that's fresh out of the charger.

TweakMDS said:

which would also be unlikely as the 4.21V measurement seems spot on for a battery that's fresh out of the charger.

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To Quote HKJ

To make people, that believe in 4.2 volt, happy, some chargers cheats and charges to above 4.2 volt. This way it is possible to measure 4.2 volt just after charge is stopped.
One well know charger that does it is the WF-139, here is one of the worst examples I have recorded:

Click to expand...

Don't get hung up on batteries not charging to 4.2V.

Sounds like the same problem as Fireclaw18, starting post 159 here:

http://www.candlepowerforums.com/vb...62-and-SC62w&p=4493197&viewfull=1#post4493197

Seems like a battery meter glitch to me... if you ordered through a dealer ask them to swap it as a defective unit. If you ordered through ZL, return it as "dissatisfied" and order another, otherwise you might risk the 2 month warranty repair route.

reppans said:

Sounds like the same problem as Fireclaw18, starting post 159 here:

http://www.candlepowerforums.com/vb...62-and-SC62w&p=4493197&viewfull=1#post4493197

Seems like a battery meter glitch to me... if you ordered through a dealer ask them to swap it as a defective unit. If you ordered through ZL, return it as "dissatisfied" and order another, otherwise you might risk the 2 month warranty repair route.

Click to expand...

Yup sounds like the same problem.

On mine it's gotten so bad that it immediately flashes down from max to medium within 1 second of turn-on even with full batteries fresh off the charger. It didn't behave this way when I first received the light. The problem only started to develop on the second day.

Clearly defective. Return to your place of purchase for replacement. Or send to Zebralight for warranty repair or replacement.

Sorry to hear you both seem to be having the same problem with different models.
@fireclaw: what corrective measures have you taken? I'm also wondering if Zebras are serialized? I don't see a S/N anywhere on mine. How do they know the light your returning is same as the light you purchased?

Jeffg330 said:

Sorry to hear you both seem to be having the same problem with different models.
@fireclaw: what corrective measures have you taken? I'm also wondering if Zebras are serialized? I don't see a S/N anywhere on mine. How do they know the light your returning is same as the light you purchased?

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There's no serial number I can see.

They'll know I returned the light I purchased when they try turning it on at their returns department and encounter the problem I reported.

All the corrective measures I tried involved cleaning or bypassing the contacts at the tail, and trying different batteries. I didn't disassemble or solder anything. There's no debris and no damage anywhere on the light. It looks pristine and it's only a week old.

Zebralight emailed me back and asked me to return the light with one of my batteries and to allow a 6 week turnaround time. Before I do that I'm going to run a battery down until the light cuts off and then pop a fresh battery in and see if that resets the calibration in the light. I'm running unprotected since the light is small but worst case scenario I ruin a battery I suppose. I also have no idea if that will work, but my motto is, when in doubt just do something. I made a post earlier but it never appeared, not sure if it's awaiting moderator approval since I'm below 3 posts or if it got lost in the internet somewhere, but I'm using this as an opportunity to pick up either an HDS or a Prometheus alpha. I'll reserve judgment on zebralight until after I deal with their customer service, I seem to be gifted in getting the one in a million problem child from any company.
Thanks all for your help so far, I'll let you all know how it goes.

It's possible that your batteries are bad and possibly fake, particularly if you purchased them from a random Amazon vendor. You might try getting one or two more from a reputable vendor. If your light works better with them, then you have bad batteries.

StorminMatt said:

It's possible that your batteries are bad and possibly fake, particularly if you purchased them from a random Amazon vendor. You might try getting one or two more from a reputable vendor. If your light works better with them, then you have bad batteries.

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Yeah, and some can't supply the high amp draw that the light uses on turbo, etc.

It's not hard to test a battery, it just takes a voltmeter and patience. And big resistors.

1 amp draw: We want to get 1 amp at 3.6v nominal voltage. This requires three one-ohm, one-watt resistors in series. You'll be over their rated current by a bit, but that's OK for short tests. Do this on a non-flammable surface, anyway. Put a pair of 3-resistor strings in parallel for 2 amps, etc.

Connect it with an ammeter to check that your current is near 1 amp, or two amps. Then take the meter out of the circuit tand check voltage. If you stay above 3.6v, you are still delivering over your target current.

StorminMatt said:

It's possible that your batteries are bad and possibly fake, particularly if you purchased them from a random Amazon vendor. You might try getting one or two more from a reputable vendor. If your light works better with them, then you have bad batteries.

Click to expand...

True.

But unlikely in my case, since I tried several different batteries and got the same result from all of them (instant step down to medium even on a fresh cell). Also, the problem developed fairly rapidly:
Day 1: Except for a very slight momentary flicker at turn-on, the light worked perfectly and could stay in H1 indefinitely.
Day 2 morning: Occasional stepdown to medium on slightly depleted cells. Happened maybe 1 out of every 5 tries. Usually happened after a few minutes of turn-on, and was less likely to happen on high discharge cells.
Day 2 evening: Stepdown happening much more frequently.
Day 3: Stepdown now occurs on EVERY cell. Even the high discharge cells. And even with fresh cells. Around 1 out of every 5 attempts the light won't stepdown and will remain in high indefinitely.
Day 4: Stepdown now occurs immediately on every cell. Even on fully charged cells straight off the charger. Light will no longer stay on high ever.

I tried the following:
Panasonic NCR18650b 3400 mAh - purchased directly from Mountain Electronics
Panasonic NCR 18650bd 3100 mAh - purchased directly from Mountain Electronics
3 different Zebralight 18650 3100 mAh - all purchased directly from Zebralight.com
2 different Samsung 25r INR 18650 (2500 mAh high discharge) - all purchased directly from Mountain Electronics

My guess is a bad solder joint somewhere in the head of the light is causing insufficient negative connection from the body to the driver. This bad connection probably developed when I ran the light on high on the first day and the heat caused the bad solder joint to almost break. Resistance caused by this bad connection is making the light malfunction.

My second SC62w arrived today. So far so good. It remains in high with no stepdown so far, and there's no flicker at turn-on. I'm using the same cells that failed in the first light, they now seem to run fine in the replacement. Hopefully, this second SC62w will continue to run fine.