Anyone who has bought non original batteries for there Nikon and had any problems. I have just bought a EN-EL4a for my battery pack ready for Silverstone and forgot about hindsight as usual. I paid £25 for a battery and charger just as a back up, my original battery is a nikon but I'm 6 days away from home and sometimes finding a socket can be a nightmare..... bloody people hogging them with phone chargers. So have I put my camera at risk in anyway or are they a smart buy??
Can't speak from personal experience as I use Canon, but on a recent shoot with a couple of friends, one of them using a Nikon D800 started having unusual problems. He took battery out, took lens off put it all back and it worked again for about 5 minutes then started playing up again. He took the battery out again (3rd party battery) and put a Nikon original in and all was well for the rest of the shoot.
Who knows! I've always used Canon original batteries and never had a problem.
I've used Nikon originals and non- Nikon batteries and never had any trouble due to the batteries. The few times I've had bother (batteries registering empty when fully charged) were down to the camera as it would happen just as often with Nikon batteries as with 3rd party ones. I'm fairly certain it was a problem with the contacts. However, I've always used the genuine Nikon chargers and am not sure I'd trust others.