False claims of rechargeable battery capacity.

Many generic Ni-MH rechargeabel bateries are claimed to have very high capacities (e.g. 1800 mAh, 1350 mAh) that are grossly exagerated.  It is not easy to test a battery's capacity quickly, but there are many ways to do it. 

The easiest way is using an electronic gadget with a known power consumption rate, and run it till the battery dies.

For example, Sony MDR-10RDC Noise Canceling Headphone set consumes 0.1 W power. Suppose a battery can last for 6 hours, the capacity of the batter should be:

0.1 x 6 / 1.2 = 0.5 Ah (i.e. 500 mAh) where 1.2 is the average voltage of the battery. 0.1 x  6 is the actual consumed power in WH (watt-hour).  

A GO!GREEN AAA 1350mAh 1.2V Ni-MH rechargeable battery:  7 hours, 583 mAh

RadioShack Nickel-Cadmium battery 300mAh: 4 hours, 333 mAh