My friend and I started with a Blu kit, then moved to the 510. When I forgot my charger for the 510, I used the blue charger with the 510 batt. (I can already see all the pros laughing...).
Of course , my batt wouldn't work, so I proceeded to do the same with my second batt...
That was stupid in itself and it got worse: she landed me one of her batts and I decided to "charge it" before returning it.
I fried 3 batts in one afternoon without blinking.
In this forum, I read that the polarity of the blu and the 510 are reversed. DUH! I checked, and sure enough...
Lesson learned!