I had a difficult time buying the OEM battery for my 18-month old E-P3, the BLS-1. I found a few OEM BLS-1 but selling for absorbent prices and I suspect were old stock. Apparently the BLS-1 battery and its charger (BCS-1) are being phased out due to a Japanese law banning trickle charging (the low power topping off at the end of the charge cycle). So I bought a Sterlingtrek BLS-1 clone but, unfortunately, it shorted out within a week and nearly fried my camera (and hand!). After a little googling I found out the newer BLS-5 battery is interchangeable with the BLS-1, the main difference being the BLS-5 has an extra contact only used by the charger. Unfortunately it requires a charger with the 4th contact, the Olympus BCS-5 Battery Charger for BLS-5 Battery, so I was forced to buy a new charger as well. Luckily, the Amazon prices were pretty good for both items, about the same price as buying a single old stock BLS-1. Not much to say other than the BLS-5 charged up fine in the Olympus BCS-5 Battery Charger and worked perfectly in my E-P3 as expected, yielding about 300 images per charge. But what a relief after the overheating Sterlingtrek BLS-1! Although the instructions warn the Olympus BCS-5 Battery Charger is only for the BLS-5 battery, my BLS-1 battery seems to charge fine in it. Glad I don't have to carry two chargers... I'm guessing most Olympus shooters here already know about the BLS-1/BLS-5 thing, but I wish Olympus made this information more obvious in their manual and battery descriptions.