Measuring SoC/life on Li-ion battery - help please

[rthomas_uk]

Hi all,

I've been trying to find some sort of multimeter/voltmeter/etc that will allow me to get an accurate (and independent of the handset) read on state of charge, or remaining life, on a standard cell phone li-ion battery.

I've found a few voltmeters and the like, but my understanding is that it's not as simple as that...?

I'd be very grateful if anybody know of such a device or can give me any information.

Many thanks,
Rich

 

[Bobbywhy]

Hi all,

I've been trying to find some sort of multimeter/voltmeter/etc that will allow me to get an accurate (and independent of the handset) read on state of charge, or remaining life, on a standard cell phone li-ion battery.

I've found a few voltmeters and the like, but my understanding is that it's not as simple as that...?

I'd be very grateful if anybody know of such a device or can give me any information.

Many thanks,
Rich

rthomas_uk, Welcome to Physics Forums!

Knowing the State-of-Charge (SOC) of a lithium-ion battery is not so straightforward. Yes, a quality voltmeter is necessary, but some calculations are needed also. See:

http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries/

And:
"If a Li-ion battery is used in applications where knowing the SOC is crucial (such as Electric Vehicles), there is a need to measure its actual capacity. The battery capacity is measured by integrating its current from completely full to completely empty (or vice-versa)."
http://liionbms.com/php/wp_soc_estimate.php