After setting up my battery capacity tester, I’ve decided to do a test on a TrustFire 18650 lithium battery I’ve bought ~1.5 year ago on DealExtreme (url). The battery specs (and label) say it’s a 2400mAh battery, but with cheap chinese batteries, it’s better to measure then believe!
The battery i have is not new, but has seen very little use (probably about 4-5 charge/discharge cycles), and has been fully charged (not good, I know) in a small battery box at room temperature for most of that time, so i was expecting some loss in capacity.
I’ve charged the battery to full using a XTAR MP15 battery charger (USB power, very slow, but seems to work well), and started the discharge measurement immediately after the LED on the charger turned green (the battery should be at 95%+ capacity then, and the charger stays in CV mode for some time after that).
And the results? With a cutoff voltage of 3.0 volts (the protection circuit should kick in at about 2.5 volts, but I wasn’t willing to risk overdischarging it), the measured battery capacity was 2.271mAh! Which is great for that price!
So now, on my TODO list: testing AA/AAA batteries, brand name vs. much cheaper, store branded ones.