When I opened the box to assemble my new Olympus E-5, I noticed the battery and charger is gray, not the traditional black. Since I’ve amassed a collection of the standard black batteries over the years, I wanted to find out what was behind the switch. I contacted Rich Pelkowski, Product Manager for the Olympus PEN and DSLR products.
It turns out, the change in battery color indicates a significant change in battery technologies. Pelkowski explained “The new battery and charger have an additional circuit to better monitor charging, and therefore the charger can charge the battery more efficiently for better run times.”
He also pointed me to a technical paper which outlines an additional feature of the intelligent batteries, their ability to stop the charging process when the battery is fully charged. This not only preserves the life of the battery by not overcharging, but it also prevents the charger from acting like a vampire power source, continually sucking power even when not actively charging.
Given that many new E-5 users also have the existing black batteries lying around, you should know the gray batteries are backwards compatible to work with your old cameras, but cannot be used with the old chargers. Nor can the old batteries be charged in the new chargers.
You may consider gradually phasing out the old black batteries and replacing them with the newer, gray batteries for better performance.