Help with dead flashlights.

whitesquirrel44

Newly Enlightened
Joined
Dec 10, 2023
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3
Location
Lafayette, LA
I have 2 single cell AA flashlights that stopped working. One is a Fenix LD11, the other is a Thorfire TG06. Both worked with 14500 3.7v Li-ion batteries as well as 1.2v NiMH and 1.5v alkaline batteries. About two months ago the Fenix stopped working. Last night I took the 14500 battery out of the Thorfire to charge it and put a Li-polymer battery in it and it stopped working immediately. I tried other batteries with no luck. I've had the Li-polymer battery for years, maybe 9 or 10, and it keeps it charge a long time. It was the first battery I bought with a micro-USB port on it. On my battery meter is shows 1.51 volts, 395 mOhms. A similar EBL AA 1.5v Li-ion with micro-USB, bought about 2 months ago, shows 1.51 volts and 3 mOhms. I don't know much about electricity but could the mOhms be the problem? My understanding is that Ohms is the amount of resistance in a wire. In general a tv coax cable needs to be 50ohms and a cb radio coax cable needs to be 75ohms. I don't know how that works with batteries.

Could the Li-polymer battery be the reason these lights died? I don't specifically remember putting the Li-polymer battery in the Fenix but I may have. I only have one and it seamed a good fit to put in a single cell AA flashlight.

Other than trying the flashlights with other batteries, is there something else I can test or check?

Thanks
John
 

jon_slider

Flashlight Enthusiast
Joined
Mar 31, 2015
Messages
5,141
> I have 2 single cell AA flashlights that stopped working

welcome to the Forum,
sorry for your loss

I see that as an opportunity to buy new lights

If you want to stay in the AA/14500 area, suggest you consider the
Skilhunt M150, here is a review
or H150, here is a review
I recommend you choose the Nichia 519a 4500K LED option.
 

LRJ88

Enlightened
Joined
May 4, 2014
Messages
647
I have 2 single cell AA flashlights that stopped working. One is a Fenix LD11, the other is a Thorfire TG06. Both worked with 14500 3.7v Li-ion batteries as well as 1.2v NiMH and 1.5v alkaline batteries. About two months ago the Fenix stopped working. Last night I took the 14500 battery out of the Thorfire to charge it and put a Li-polymer battery in it and it stopped working immediately. I tried other batteries with no luck. I've had the Li-polymer battery for years, maybe 9 or 10, and it keeps it charge a long time. It was the first battery I bought with a micro-USB port on it. On my battery meter is shows 1.51 volts, 395 mOhms. A similar EBL AA 1.5v Li-ion with micro-USB, bought about 2 months ago, shows 1.51 volts and 3 mOhms. I don't know much about electricity but could the mOhms be the problem? My understanding is that Ohms is the amount of resistance in a wire. In general a tv coax cable needs to be 50ohms and a cb radio coax cable needs to be 75ohms. I don't know how that works with batteries.

Could the Li-polymer battery be the reason these lights died? I don't specifically remember putting the Li-polymer battery in the Fenix but I may have. I only have one and it seamed a good fit to put in a single cell AA flashlight.

Other than trying the flashlights with other batteries, is there something else I can test or check?

Thanks
John
Have you already tried with all batteries available to you? What charger did you use that also showed internal resistance? The Li-ion and LiPo batteries sound way too low, they should be around 4.2V after charge and have an internal resistance of 50-200 somewhere which means that something is off there as well.
 

jon_slider

Flashlight Enthusiast
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Mar 31, 2015
Messages
5,141
The Li-ion and LiPo batteries sound way too low
actually not
LiIon is nominally 3.7V although they do charge up to about 4.2V. So, 3.7V is half full.

the cells he is calling LiPo seem to actually be the rechargeable LiIon that use a chip to step down the voltage to 1.5V for use in AA devices.

so, if the lights also dont work w Alkaline nor Eneloop that he said he has, then the lights are dead and should be replaced. The lights seem to be about 5 years old, so, thats not a bad run for the price.
 

LRJ88

Enlightened
Joined
May 4, 2014
Messages
647
actually not
LiIon is nominally 3.7V although they do charge up to about 4.2V. So, 3.7V is half full.

the cells he is calling LiPo seem to actually be the rechargeable LiIon that use a chip to step down the voltage to 1.5V for use in AA devices.

so, if the lights also dont work w Alkaline nor Eneloop that he said he has, then the lights are dead and should be replaced. The lights seem to be about 5 years old, so, thats not a bad run for the price.
3.7 is half full, but as he mentioned they were reading below 2V. If it's the case that it's converted down to regular alky voltages it should be fine, but with the internal resistance of them it might be an issue with the cells as well messing with it both ways.

It'd be interesting if a reading could be done with the cell in the flashlight to see what happens then.
 

whitesquirrel44

Newly Enlightened
Joined
Dec 10, 2023
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3
Location
Lafayette, LA
I want to thank everyone for their replies.

I've included a picture of the batteries and the tester that is gives me those numbers. The blue one is a 3.7v (that's what it says on the battery) Li-ion no-name, no-blame Chinese battery that is now fully charged. The EBL is a 1.5v Li-ion with a micro-usb charging port. The black/green battery is the old 1.5v Li-polymer (it says Li-polymer on it) with a micro-usb charging port. It also has "Quality Standard: GB31241-2014" on it. I guess that means it's not quite 10 years old now. That is the battery in question here.

Update: In response to LRJ88 remarks, I retried all the batteries in both lights again. To my surprise the Thorfire TG06 works with the 3.7v Li-ion battery (blue one in the pic) but the Fenix does not. The Thorfire still will not work with a 1.5v alkaline (standard Duracell) nor the 1.5v Li-ion EBL nor a 1.2v NiMH batteries. While I'm happy it works, it defeats the purpose of having a single cell AA flashlight.

The blue 3.7v Li-ion battery is now fully charged and tested at 4.12v with 65mOhms. I retested the Li-polymer battery and it shows 1.51v with 374mOhms, then again with 350mOhms, then again with 311mOhms, then again with 331mOhms. I don't know what that means but I should mention that there is no 1.5v Lithium setting on my meter so I'm using the 1.5v Alk AAA/AA/C/D setting. I just tested it again on the 3.2v LiFeO4 setting and it shows 1.50v with 465mOhms and again on 3.7v Li-ion setting that showed 1.51v with 495mOhms.
 

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jon_slider

Flashlight Enthusiast
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Mar 31, 2015
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5,141
ok, so the Fenix is totally dead and the Thorfire only works on LiIon

good job figuring that out

If you dont want to spend the cost of the Skilhunt, maybe consider an AA/14500 Lumintop Tool.. they are less expensive..

you could also contact Fenix about your dead light, maybe they want to send you a free replacement ;-)
 

LRJ88

Enlightened
Joined
May 4, 2014
Messages
647
I want to thank everyone for their replies.

I've included a picture of the batteries and the tester that is gives me those numbers. The blue one is a 3.7v (that's what it says on the battery) Li-ion no-name, no-blame Chinese battery that is now fully charged. The EBL is a 1.5v Li-ion with a micro-usb charging port. The black/green battery is the old 1.5v Li-polymer (it says Li-polymer on it) with a micro-usb charging port. It also has "Quality Standard: GB31241-2014" on it. I guess that means it's not quite 10 years old now. That is the battery in question here.

Update: In response to LRJ88 remarks, I retried all the batteries in both lights again. To my surprise the Thorfire TG06 works with the 3.7v Li-ion battery (blue one in the pic) but the Fenix does not. The Thorfire still will not work with a 1.5v alkaline (standard Duracell) nor the 1.5v Li-ion EBL nor a 1.2v NiMH batteries. While I'm happy it works, it defeats the purpose of having a single cell AA flashlight.

The blue 3.7v Li-ion battery is now fully charged and tested at 4.12v with 65mOhms. I retested the Li-polymer battery and it shows 1.51v with 374mOhms, then again with 350mOhms, then again with 311mOhms, then again with 331mOhms. I don't know what that means but I should mention that there is no 1.5v Lithium setting on my meter so I'm using the 1.5v Alk AAA/AA/C/D setting. I just tested it again on the 3.2v LiFeO4 setting and it shows 1.50v with 465mOhms and again on 3.7v Li-ion setting that showed 1.51v with 495mOhms.
When cells get that high internal resistance i tend to chuck them away, i prefer them at 400 at the most to not run into issues of them either not performing at all or perfoming really fast as a blowtorch.

It almost sounds as if the curcuitry on the Thorfire has started failing, i don't know when you bought it but as John_Slider above mentioned it could be worth checking the warranty on that as well as the Fenix.
 

whitesquirrel44

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Joined
Dec 10, 2023
Messages
3
Location
Lafayette, LA
I will check the warranties. I will chunk the battery (by that I mean bring it to Lowes and deposit it in the recycle box, for those who would say not to put it in the trash). I'm afraid to ruin another light whether it was the culprit or not. I have several other 2-AA lights so I won't buy any new ones. Thanks to all.
John
 
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