Slightly off topic, but the advice was given to me by the Component shop. If you are tempted by cheap batteries, the dodgy ones with fictional capacity ratings. Then the weight of the battery is a good guide.
I fell for this 5 years back and the 6 cell pack I bought via YKW weighed the same as just 5 cells, and further testing showed an actual capacity of 1450mAh against the printed 3800 mAh.
You pay for what you get!
Regards Roy