There is no such thing on sale in the US as a rechargeable, battery-powered coffee-grinder. We have rechargeable battery-powered saws and angle-grinders but not coffee grinders. I don't know why but I suspect a patent troll.
Anyway so if you like freshly ground coffee as I do, on a boat, the options are limited to using an inverter to power an electric grinder -- and a coffee grinder doesn't really burn a lot of power -- or using a manual grinder.
The problem with the manual grinders are that they require two hands to operate, except for the wall-mounted ones which instead are usually very large and ornate pieces with glass bits that would never safely fit on my boat. On a boat, you need at least one hand to hold onto something, so you rarely have both hands available to make coffee.
However I was lucky to find this particular grinder on Amazon, and thus far I'm happy with it but for a single issue: the little bowl that receives the coffee below, attaches to the body of the grinder only with magnets. This means that the slightest bump of the finger and the receptacle and ground coffee it contains goes flying everywhere. I wish instead of magnets, the receptacle was screwed-in. Anyway that's my only problem with this grinder. The receptacle is perfectly sized for a single cup of coffee in my shatter-proof coffee press. The aluminum body can take the humidity of the sea as can the ceramic blades. It grinds coffee pretty fast too, I haven't counted the turns but It doesn't seem to take much more time than using a regular coffee grinder.