How to determine which battery is new one?

I have 2 batteries for my mobile, and forget which one is new and old.
The standard volt is 3.6 V, and I measure the voltage using any standard electric meter.
Battery A has 3.86V
Battery B has 3.77V

Does anyone have any suggestions on whether it is possible determine the new battery based on measured volt or not?

Thanks in advance for any suggestions :>

1 person

mfb
Mentor
Can you charge both to 100%? Otherwise, I would expect the charge state to be more significant than the age.
Do you have a small resistor? Something like ~50 Ohm. Connect it to the two terminals, and measure the voltage while the load is applied. A better battery will have a smaller voltage drop compared to the setup without load.

I get following meter, will it be possible to measure it using this device?

Do you have any suggestions?

Thanks you very much for any suggestions :>

Meter
http://www.uni-trend.com/UT10a.html [Broken]

Manual
http://www.uni-trend.com/manual2/UT10A%20Eng%20Manual.pdf [Broken]

Last edited by a moderator:
mfb
Mentor
That is a simple voltage measurement, every multimeter can do that.

I have 2 batteries for my mobile, and forget which one is new and old.
The standard volt is 3.6 V, and I measure the voltage using any standard electric meter.
Battery A has 3.86V
Battery B has 3.77V

Does anyone have any suggestions on whether it is possible determine the new battery based on measured volt or not?

Thanks in advance for any suggestions :>

Yeah... look at the serial numbers on each battery. I'd bet the larger serial number is the newer battery.

davenn
Gold Member
2021 Award
Yeah... look at the serial numbers on each battery. I'd bet the larger serial number is the newer battery.

there we go !! what a brilliant answer

you really cannot go by voltage as the older battery may still be capable of charging to its new condition maximum. And apart from that, there's likely to be minor variations in full charge voltage of new batteries anyway!

Dave

meBigGuy
Gold Member
The best way is to see which lasts longer in the cell phone.

The only other way I know of is to measure the internal resistance by applying a load and measuring the change in voltage.
Both batteries should be fully charged and then partially discharged to around 3.7V. Then measure the voltage drop when you apply a 33 ohm resistor. The lower voltage drop is the better battery.