My Canon 40D was purchased in 2008. The Canon factory battery is showing end of life signs. So, I purchased a set of INSTEN Batteries for Canon BP-511 batteries. These INSTEN definitely hold their charge much longer than the old Canon's. I have been using the Canon factory battery charger on the INSTENs. Just like with my XSi batteries, I think I better get an INSTEN BP-511 charger. Plus, it makes sense to have two chargers, trying to charge up 4-batteries for a photo shoot can take up a lot of time, when using only one charger.
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