18650 Doesn't Fully Charge

flashfan

Flashlight Enthusiast
Joined
Aug 2, 2001
Messages
1,298
Location
USA
I did a quick search on this subject, but couldn't find any threads. If this topic has been covered before, thanks for a point in the right direction.

In any event, thanks to the recommendations on this forum, I purchased an Xtar battery charger, VC4 Plus. Seems so superior to my old Nitecore Intellicharger, but now here's the rub. The Xtar shows the batteries' mAh during and after full charge. However, I've noticed that the Nitecore 3500 mAh batteries don't charge up anywhere near the 3500mAh number. And these batteries have had very low use, so it's not as though they're worn out.

Am I doing something wrong or reading the display incorrectly? Or is there a tip to get the best performance? Or is it the flashlight I'm using the batteries in...the Nitecore TM06S? When I first got the light, it performed really well and the batteries lasted a long time. Now, even with replaced, freshly charged batteries, the light doesn't last long. Perhaps there is a parasitic drain, but my biggest concern is the mAh shown on the charger.

Thanks for any help and ideas.
 
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aznsx

Enlightened
Joined
Apr 24, 2015
Messages
670
Location
Phoenix, AZ USA
I did a quick search on this subject, but couldn't find any threads. If this topic has been covered before, thanks for a point in the right direction.

In any event, thanks to the recommendations on this forum, I purchased an Xtar battery charger, VC4 Plus. Seems so superior to my old Nitecore Intellicharger, but now here's the rub. The Xtar shows the batteries' mAh during and after full charge. However, I've noticed that the Nitecore 3500 mAh batteries don't charge up anywhere near the 3500mAh number. And these batteries have had very low use, so it's not as though they're worn out.

Am I doing something wrong or reading the display incorrectly? Or is there a tip to get the best performance? Or is it the flashlight I'm using the batteries in...the Nitecore TM06S? When I first got the light, it performed really well and the batteries lasted a long time. Now, even with replaced, freshly charged batteries, the light doesn't last long. Perhaps there is a parasitic drain, but my biggest concern is the mAh shown on the charger.

Thanks for any help and ideas.
I'm not familiar with that particular charger, but here's a couple of basic related points, which you may already be aware of, but...

If you charge a cell that's at an unknown SOC (state of charge), and charge it until it is deemed fully charged by the charger, the charger may provide the number of milliamp-hours it delivered to fully charge the cell to 100% SOC. That number is co-dependent on / determined by both the SOC when charging began, and how many mAh were required to charge it, and is not indicative of the total capacity of the cell.

If your charger has a 'discharge test' function, then you may fully charge the cell, then run the discharge test, and the charger will likely tell you the total mAh measured while discharging the cell from 'fully charged', down to the minimum discharge voltage where the discharge test terminated. That number should be indicative of the actual measured capacity of the cell, and should be comparable to the advertised capacity of the cell in mAh.

EDIT: Just to add, this assumes that the minimum discharge voltage used by the cell manufacturer for specification of its capacity is the same as the minimum discharge voltage used by the your charger's discharge test function, which may or may not be the case, so if they are different, you'd need to factor that in.

Hope that makes sense, but it may or may not answer your question:)
 
Last edited:

Lynx_Arc

Flashaholic
Joined
Oct 1, 2004
Messages
11,212
Location
Tulsa,OK
I did a quick search on this subject, but couldn't find any threads. If this topic has been covered before, thanks for a point in the right direction.

In any event, thanks to the recommendations on this forum, I purchased an Xtar battery charger, VC4 Plus. Seems so superior to my old Nitecore Intellicharger, but now here's the rub. The Xtar shows the batteries' mAh during and after full charge. However, I've noticed that the Nitecore 3500 mAh batteries don't charge up anywhere near the 3500mAh number. And these batteries have had very low use, so it's not as though they're worn out.

Am I doing something wrong or reading the display incorrectly? Or is there a tip to get the best performance? Or is it the flashlight I'm using the batteries in...the Nitecore TM06S? When I first got the light, it performed really well and the batteries lasted a long time. Now, even with replaced, freshly charged batteries, the light doesn't last long. Perhaps there is a parasitic drain, but my biggest concern is the mAh shown on the charger.

Thanks for any help and ideas.
It doesn't sound like the chargers are at fault but rather the batteries themselves have been damaged and it is possible that they have developed high internal resistance that would cause them to not deliver full power to the light and also in use would cause them to heat up more than normal. I don't know if either of your chargers can test for internal resistance or not. I think one test would be to try and run the light in lower modes and see if runtimes at the capacity the charger shows matches runtime and then higher modes and compare runtimes. I'm not sure of the power drain but this light could be pushing the batteries to their limits and if you operate it on the highest output all the time you could possibly just wear them out quicker than expected. I would refer to others here more knowledgeable about using these monster output lights vs batteries.
 

DRW

Newly Enlightened
Joined
Mar 27, 2022
Messages
136
Location
Michigan
Think of the battery like a fuel tank in your car. You may have a 26 gallon tank. When you notice you need fuel, you stop and fill up. At least for me, that means 20 to 22 gallons of fuel added. The pump doesn't know how big the tank is, just how many gallons were dispensed.

I think the charger is simply reporting how much energy was added to the battery. Not the capacity of the cell.
 
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