Tenergy 3.0V RCR123A final voltage?

[HDCharlie]

I have four brand new Tenergy 3.0V, 900 mah, RCR123A batteries and the corresponding Tenergy charger. Why would these cells come off the charger at a final voltage of 3.85 - 3.90 volts? I thought they should be closer to 4.2V when the charging light turned green. A little education might be all I need here.

 

[mdocod]

The "voltage reduction circuit" (couple o' diodes) probably has the effect of causing a ~0.3V drop under little to no load, and as soon as a larger load kicks in, it drops down the full ~0.7V.

 

[Metatron]

i have the same setup for my jill lite, and the batts come off the charger at 4.2v. during charging its at 4.5v. its got me stumped as to when is a 3 volt batt not a 3 volt batt?

 

[mdocod]

The difference you are seeing actually may have more to do with the meters you are using the test the cells voltage with... To test voltage, the meter must draw a very small amount of current, some meters may use more or less than others to perform this test, the 4.2V reading may be coming from a meter that uses a fraction of the current of the one that only read 3.9V on the same cell types.

 

[FLT MEDIC]

I have four brand new Tenergy 3.0V, 900 mah, RCR123A batteries and the corresponding Tenergy charger. Why would these cells come off the charger at a final voltage of 3.85 - 3.90 volts? I thought they should be closer to 4.2V when the charging light turned green. A little education might be all I need here.

The Tenergy 3.0V, 900 mah, RCR123A batteries require a 4.2 volts charger and will not be fully charged by a 3.6v charger like other brands of protected RCR123A batteries. As soon as the charger shuts off, its voltage will be between 3.6v to 3.9v. After a few minutes, it will drop to 3.1v to 3.2v that's why it has been safe to use these past 2 yrs in my Gladius.

It's specs can be found at http://www.batteryjunction.com/rc390reliba.html

 

[alfreddajero]

Here it is.........

 

[HDCharlie]

I really hate to seem stupid about this, but what in that chart tells me what the batteries final charged voltage should be? You can tell I wasn't an EE major, huh?

Here it is.........

 

[HDCharlie]

The Tenergy 3.0V, 900 mah, RCR123A batteries require a 4.2 volts charger and will not be fully charged by a 3.6v charger like other brands of protected RCR123A batteries. As soon as the charger shuts off, its voltage will be between 3.6v to 3.9v. After a few minutes, it will drop to 3.1v to 3.2v that's why it has been safe to use these past 2 yrs in my Gladius.

It's specs can be found at http://www.batteryjunction.com/rc390reliba.html

I'm using the charger Tenergy supplies with the cells. It was part of a blister packed kit.

 

[mdocod]

Actually the tenergy 3.0V 900mAH cells require a 4.4V charger, not a 4.2V charger. In the case of "3.0V" RCR123s, I always recommend only using the charger sold with those cell "kits" as there are different types of 3.0V cells out there with different charging requirements.

 

[HDCharlie]

Actually the tenergy 3.0V 900mAH cells require a 4.4V charger, not a 4.2V charger. In the case of "3.0V" RCR123s, I always recommend only using the charger sold with those cell "kits" as there are different types of 3.0V cells out there with different charging requirements.

Correctomundo!! When charging, measuring across the terminals shows ~4.4V, but the cells show ~3.85V at the green light. I guess I just have some bad cells. I don't think my meter is bad, because any 3.7V cells I charge on my Pila come off right at 4.2V, just like they should.

 

[mdocod]

Correctomundo!! When charging, measuring across the terminals shows ~4.4V, but the cells show ~3.85V at the green light. I guess I just have some bad cells. I don't think my meter is bad, because any 3.7V cells I charge on my Pila come off right at 4.2V, just like they should.

your cells are more than likely FINE!

The ~3.8V reading is perfectly normal, and is the result of the circuitry built into the cell that is designed to cut the operating voltage to around 3V when loaded. Again, there is very likely NOTHING wrong with your cells.

Again, I must point out, that the exact voltage readings taken on this type of cell is going to vary depending on the meter used to test it, as the more current the meter draws to perform the test, the greater the effect will be on effective voltage by the built in voltage shunting circuit.

Eric

 

[alfreddajero]

I also tested one that was charged last night.......its one that was in the light and it also reads 3.7-3.8 volts........i have other rcrs that read 3.2-3.4 off the charger. Your cells are just fine and i have been using these cells with no problems thus far.

 

[metlarules]

Like others have said your cells are fine. I have the same cells. When I take them off of the charger upon completion of charge they read 3.85v.

 

[alfreddajero]

Just remember that when its in use it will take about 12ms for it to switch to 3volts, so be careful what light you use.

 

[HDCharlie]

OK, everyone. I'm thick-headed, but I finally see what you've been trying to tell me. Thanks for all your replies and your patience. I know how hard it can be tolerating the questions from someone who just doesn't get it yet. I was a Service Manager in a Harley dealership, and most of my day was spent answering some pretty dumb, to me, questions. I dealt with them as patiently as possible and made many good customers. I can see why this small community has as many "repeat customers" as it does. The ones of you who know, don't treat the ones of us who don't, as complete morons. You seem to understand that some of us just don't know, but really want to learn. Again, many thanks. :twothumbs

 

[alfreddajero]

Isnt that why were here to learn and to help others........why would there be a forum right.

 

[FLT MEDIC]

Correctomundo!! When charging, measuring across the terminals shows ~4.4V, but the cells show ~3.85V at the green light. I guess I just have some bad cells. I don't think my meter is bad, because any 3.7V cells I charge on my Pila come off right at 4.2V, just like they should.

In that case, your Tenergy charger relies on the internal protection circuit of the Tenergy protected RCR123A which will stop accepting charge when the charger voltage reaches between 4.300v to 4.375v based on its spec sheet/chart above. The charger LED in turn turns green.

If I use my homebrew 4.4v charger to charge my Tenergy RCR123A, it stops charging when it reaches 4.3v and drops to 3.2 volts after a few minutes even while connected to the charger terminals.

In short, your Tenergy batteries are ok.