I will go on an three-week camping trip around Iceland. My primary power sources will be the 12V socket of the mini camper (while the engine is running) and a 62Wh power bank (charged via the 12V socket with a USB charger). The camper itself has no 220V supply, so even if there is a "regular" power supply on camp sites, it might not be very convenient to use that (let's say it is raining).
Which charging equipment would you recommend in that situation?
I came across USB battery chargers like this one for the Nikon EN-EL15 battery (I have a Nikon D7000). I could use it with the 12V car USB charger and the powerbank (and also with a USB wall charger if I come across a usable 220V outlet). Also, it is small and I would not need to carry the original MH-25 charger (and cable) which is quite bulky.
The reviews I read are quite mixed (as with many cheap 3rd party accessories). Some claim that a 2-pin charger may even damage the battery, opposed to the original 5-pin charger.
Are there any (verified) objections against such chargers?
Side note: I am also thinking about buying a second battery. From my travelling experience, going with two fully charged batteries should (almost) be sufficient for three weeks. It increases the likelihood to have access to a 220V socket before both batteries are empty. I would have to carry the original charger but I would not have to rely on cheap equipment. What do you think?
Update 2022 (for the record)
I went with an RP-PB057 (dual EN-EL15 USB-Charger from RAVPower) and have used it ever since without problems. Turned out I was worrying a bit too much beforehand. The only issue was that the powerbank ran a bit low on occasions having to charge two smartphones and two camera batteries throughout the journey, draining more power than the car charger could supply. However, I could usually use regular 220V outlets in communal areas of the campsites (the rally point of the 21st century outdoor traveller 😉️).