Bests & Worsts Reviews from Amazon

I purchased my D7200 recently, and I needed to get a backup battery ASAP. With a backlog on the EN-EL15, I paid the extra $10 for the EN-EL15a. The battery is great, and because it's an OEM part I know I won't have problems like I have in the past with the cheaper aftermarket alternatives. I tried some of those in the past with my D5300 and it was a complete failure. As to any differences between the two versions of this battery; I see none. Both the EN-EL15 and EN-EL15a are 7.0V 1900mAh 14Wh (don't believe the guy who answered incorrectly about the capacity in the Q&A section) . In another one of the questions someone had answered that the original EN-EL15 was Li-ion10 and the EN-EL15a is Li-ion20, but in my case both batteries are Li-ion20. The only noticeable difference is the color (EN-EL15 is black and the EN-EL15a is grey). If you can wait and you want to save ten bucks you may want to go for the original EN-EL15, but I can't say whether or not the one you get will be Li-ion20. Update: After a bit more research, I found that this battery model was originally offered as a free replacement from Nikon to owners due to problems in some camera models. It would seem that the updates have been rolled into the standard EN-EL15. I also posted a picture with both batteries side-by-side. I was recently at a weekend wedding, and I took around 700 pictures over the course of 2 days without changing this battery. I wasn't doing a lot of reviewing, I have an external speed-light, and I don't use my camera wi-fi which all help with battery life. My experience also tells me that these batteries do take a couple of charge cycles to reach maximum capacity, so don't be upset if it dies a little quicker when you first get it. I hope that this review helps sort out the differences between this model and the original. If you have any other questions please ask and I will do my best to answer.