The largest capacity AA rechargeable batteries at this time are about 2900mAh yet there are people currently selling batteries on ebay with a much greater capacity. These are fakes. For example Sony's highest capacity AA rechargeable batteries have a capacity of 2500mAh (see http://products.sel.sony.com/battery/rechargeable.htm  ) yet there are batteries sold on ebay labelled as Sony with capacities of 3600mAh and 4300mAh
which are obviously fakes and do not have these capacities. Likewise Sony's highest capacity AAA rechargeables have capacities 900mAh therefore Sony AAA rechargeables with capacities of 1100mAh and 1350mAh are fake. Sony's older NiMh AA genuine B2C batteries have capacities of 1100mAh  so sellers on ebay selling AA B2C batteries with 1300mAh capacities are selling fakes however Sony did make AA B2D's at 1300mAh (see http://forum.lowyat.net/lofiversion/index.php/t186663-150.html  for more details).

Obviously there are also huge numbers of  fake batteries in other brands and it would take too much time to identify them all here. Any logo can be painted on any battery so buyers beware. Check prices and capacities on well known internet store web sites before purchasing rechargable batteries because the reputable online stores can't seem to get close to prices of many of these branded batteries for sale on ebay. You should be suspicious of  any rechargeable high capacity batteries that seem to be available only on ebay. For example do a Google search for AAA 1800mAh and AA 3200mAh of any brand and ebay is the only place you'll find them. Although it is possible to pick up good bargains on ebay the prices of  many of these batteries seem  too good to be true so it is wise to be suspicious. Don't be fooled by 100% positive feedbacks; ask the seller questions as to why their batteries are so cheap and where they are sourced from and then check with the manufacturer that these batteries are from legitimate suppliers. Just a couple of short emails and a Google search can help you to avoid being conned.

If you want to use rechargeable batteries in expensive equipment such as Mp3 players or digital cameras you should be extra careful to buy quality batteries from a brand you trust because poor quality batteries are not halmless and may leak into your equipment and ruin it.

If you found this guide helpful please vote to keep it highly placed in ebay searches for batteries so that others may also find it.