3xAAA headlamp discharged eneloop pro to .11v, 1.27 v, 1.27v! Please explain

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yclongthrow
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3xAAA headlamp discharged eneloop pro to .11v, 1.27 v, 1.27v! Please explain

I was doing a runtime test and one of the “Fujitsu” eneloop pros was at .11v afterwards and refused to charge. Is the cell fake/bad? Did the headlamp cause this? Should I repeat with another set or is there risk that I will end up with another .11v(due to the headlamp)?
Thanks

EDIT:
About 15 minutes after pulling out of the lamp(which was still “on” high mode but not producing light for at least the last 7 hours) the cell has rebounded to .85 v.

Edited by: yclongthrow on 11/18/2016 - 18:12
yclongthrow
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Also, could it be due to heat? The test was done on high but the lamp is only 100ish lumens. Plastic body, but was not very hot to touch. It was 90 minutes when I fell asleep.

EasyB
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It looks like that one cell discharged completely before the other two. I assume all the cells are in series in the light.

I don’t have as much experience using nimh cells. I understand that eneloops are quality cells so a cell with significantly less capacity is prob uncommon, but possible. Or the cell was not fully charged as much as the other two. This is the main thing I don’t like about using nimh cells; the indication that the cell is fully charged can be ambiguous and chargers can over-charge or not fully charge because of it.

Lexel
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It can happen if one cell had at start a lot less capacity as the other 2 cells

If the battery wont charge in your charger you can try to recover it with a constant current till it has a healthier voltage
If the capacity showing on a smart is lower than your other cells its best to recycle it

WalkIntoTheLight
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It’s pretty difficult to put a reverse charge on an Eneloop (which can kill it), so your cell should be okay. Now that it’s rebounded to 0.85v, it should be able to be charged in a regular smart charger.

Perhaps it’s a weak cell. After fully charging it, measure the capacity and compare it to other cells. If it’s much lower, then only use it in single-cell devices, like a 1xAAA light.

I’ve never had any Eneloops that are weaker than others, unless the manufacturing dates are years apart. But I only use regular Eneloops, not the pros. It may be more difficult to manufacture the pros to be as consistent as the regular Eneloops are.

Enderman
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I don’t think it’s possible that the lamp caused that.
This seems like an issue with either
1) cell was already discharged more than the others when put into the lamp
2) cell is of lower mAh that other cells
3) cell is defective/abnormal (different internal resistance maybe?)
4) cell is nearing end of life and even though it will charge to the normal voltage it will deplete extremely quickly

I would suggest recharging it and see how many mAh your charger says it put into the battery.

yclongthrow
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This was the first time using the cells, all out of the same package. I don’t have a charger with a capacity test function. I may get one soon. The cells at start were 1.42 v, 1.42 v, and 1.39 v. Not sure which one of those ended up being .11v lol. I charged two cells in slots 1 and 3 of a nitecore i4. One in slot two, 18650 in slot 4. The slot two cell did finish charging 30-40 minutes before the other two. The cells fresh out of package all showed 1.30 v if I remember correctly.

I did get these on eBay for 16/$22 so they are semi-suspect. I made a thread in the battery forum and people vouched for the seller though.

RobertB
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What kind of headlamp are we talking about here?

Ronin42
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This is why the LiitoKala Engineer Lii-500 is so handy you can also look at (a ball park) internal resistance and see if maybe they slipped you a bad cell.

(“It’s good that most people can’t remember their previous lives. Otherwise
things would be a lot more complicated than they already are.”
Ajaan Lee Dhammadharo)

snakebite
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sounds like that cell false terminated.
being nowhere near full naturally it ran down first.
they will be less likely to do that after a few cycles.
mark that cell and watch it.

yclongthrow
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https://m.aliexpress.com/item/32749583072.html

Here is the headlamp. Great deal for less than two bucks. Unless of course it’s ruining eneloops lol

WalkIntoTheLight
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yclongthrow wrote:
This was the first time using the cells, all out of the same package. I don’t have a charger with a capacity test function. I may get one soon. The cells at start were 1.42 v, 1.42 v, and 1.39 v. Not sure which one of those ended up being .11v lol. I charged two cells in slots 1 and 3 of a nitecore i4. One in slot two, 18650 in slot 4. The slot two cell did finish charging 30-40 minutes before the other two. The cells fresh out of package all showed 1.30 v if I remember correctly.

I did get these on eBay for 16/$22 so they are semi-suspect. I made a thread in the battery forum and people vouched for the seller though.

Yeah, that 1.39v cell terminated before getting a full charge. It might be the charger, but the first time you charge a brand new cell, it can be a little more sensitive than after a couple of full charge-discharge cycles. Keep an eye on the final voltage level for the next few times you charge these cells.

Hot off the charger, a fully charged Eneloop cell should be around 1.50v. But that will quickly drop off to 1.45v within an hour, and continue falling to about 1.40v after a day. If you’re only getting 1.42v as soon as the charger terminates, then you’re not getting a full charge. It’s close to a full charge, but you’ve probably got another 10% to go.

If all your cells are terminating at 1.42v (or less) on that charger, I’d blame the charger.

battery
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In my experience AAA Eneloop are really poor compared to their bigger AA brothers. If you drain them that low they seem to develop very high internal resistance to where my smart chargers will refuse to charge them unless I do some tricks. I would not use the weakened one together with the others anymore.

eebowler
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charging the NiMH with the Li Ion is likely what caused the early, full charge status. HJK’s review of the charger is out there and performance with two different chemistries charging at the same time isn’t the best.

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