Protected 17500 cells quit early: Is it heat?

Paul_in_Maryland

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I'm using AW's protected 17500 cells in my Streamlight TL-3 and LEDWave Z-3. I've read that the TL-3 draws about 1.2A, suggesting that it's draining the cells at about 1.1C. Well, the cells are lasting just 25 to 28 minutes continuous before the light shuts off. With a capacity of about 1100 mAh at 0.2C, shouldn't I be getting more runtime?

I thought that the cells were shutting down because of heat; the TL-3 body, in particular, gets hot. But the Z-3 body remains fairly comfortable to hold, yet it's yielding the same runtime. And even after I let the lights cool down, there's no more juice.

By contrast, my Wolf Eyes 9MX yields 60 minutes from its AW 18500 protected cells (rated 1500 mAh). That's 10 minutes longer than Wolf Eyes claims for its 1300 mAh 150A cells. The Wolf Eyes body stays cooler than either of the other two lights.

What kind of runtimes are others achieving from protected 17500 cells in a TL-3? Is runtime degraded by heat? Or are the TL-3 and Z-3 drawing more current than I realized--on the order of 1.8A?
 

wptski

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Most but not all Li-Ion cells will have less capacity with a higher load. One that comes to mind that hardly dropped when the load was increased was the MP123 cells sold by AW.
 

VidPro

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yes heat bad, most of this stuff is designed to work best at human type room temperatures. high heats (like in laptops) are causing premature failures of the li-ion batteries.
on the other hand, it just depends on how much heat.
do your same test , with some fresh li-ions and do it in discharge cycles that stop when the heat internally to the battery is to high.
like discharge for 20 minutes, wait 30, 20, 30 etc, and see if you get more total capacity.

what he said, set it up so you can check the battery voltage under the load.
you will see that protected cuts out somewhere between 3.0-2.0 , usually about 2.4-2.5.
if the thing discharging them is really droping the voltage from high discharge rate, it can get to the low cutoff before the capacity of the battery is actually diminished.

the quality and ammount of resistance in the protection curcuit can also add to what the protection curcuit sees as a voltage drop (vdrop over the connecting wires).

take a LOOK with about any battery with a heavy load on it, and measure the voltage , you see how they drop in voltage.
or just look at silverfoxes discharge charts.

depending on the protection curcuit, it will not reset, untill a charge current passes in the other direction. so even if it does have voltage and capacity, the protection has triggered, and expects you to charge now, before discharging it further.

a light with a Incadescent bulb or a florescent, can have a higher starting discharge rate for the battery. or can hard hit the battery on turn on, and trigger an already low , low voltage cutoff. that is why LEDs are so cool with these.

the smaller battery is much more likely to voltage drop than the larger, especially when your larger battery is a med capacity, high discharge type.

and YES, you should certannly be able to get more runtime than that, IF your total amperage use is that low. i suspect that its not as low as that.
 
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AW

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Paul,

Have you tried all four 17500s ? Do they all behave the same? Please make sure they are fully charged to at least 4.1V.

The heat should have little effect on the performance if it is under 60 degree C. My TL-3 has a 60 minute runtime on these batteries and yours shouldn't be far off.

Please let me know.

Regards,
AW
 

Paul_in_Maryland

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I haven't kept track of which cells were in which body (TL-3 or Z-3), but I've definitely used all four cells in one body or the other.

I think I'll try intermittent usage to allow cooldown and see what happens. I'm 49, and I can't think of a single time in my life that I've used a flashlight longer than 15 minutes!

I don't have a way to test voltage under load, but I recently received two of Emilion's low-cost portable battery testers from Emilion with digital readout, so at least I can now test my 3.0 and 3.7V 123A, 150, and 168 cells without load.
 

Phaserburn

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Hmm, I haven't tried my TL-3/17500s in a continuous burn fashion, but I'll try to do so this weekend. I haven't noticed any patterns yet.
 

pilot4x4

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I ram my TL-3 / 17500 setup for around 35 minutes straight last night while searching the woods on my property and it was still going strong after that time. The batteries had at least 9 or 10 minutes of runtime on that charge prior to running for the 35 minutes. John
 

Dukester

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I haven't had any issues with my 17500's in my TL-3 but have to admit that I have never had a reason to run it continous for an hour. So far I have been happy with the the setup, really happy...
 

Paul_in_Maryland

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I may have found the problem: I checked the voltage of a pair of cells that had been charged a couple days before but not used. One was a healthy 4.08V, but the other was 3.54V. I'm thinking that the second cell isn't holding a charge or isn't charging to a high enough voltage.
 

Dukester

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Paul_in_Maryland said:
I may have found the problem: I checked the voltage of a pair of cells that had been charged a couple days before but not used. One was a healthy 4.08V, but the other was 3.54V. I'm thinking that the second cell isn't holding a charge or isn't charging to a high enough voltage.

Which charger are you using?
 

AW

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Paul,

I don't think the second cell ( the 3.54V one ) has been charged at all. Please try charging them one at a time on different bays and you 'll see whether the problem is from the cell or the charger/ charging bay.

Regards,
AW
 

Paul_in_Maryland

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I must say, I can't get this charger to work reliably. I'll stick a cell in, and the charge LED remains unlit. I'll swap bays, and most of the time, the LED will begin to blink. Or I'll remove the cell and try charging the other cell, and most of the time, the LED will begin to blink.

AW, I should receive your DSD charger any day now. When I've had a chance to see if it succeeds where my first charger didn't, I'll report back.
 
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