Hi Lg, if you only need to run a 10w pump a little alty will be enough, pretty much any nissan micra has a 55amp or so alty, regs have been built in most alty's for a long time.
There are 3 wires, bigun from the case of the alty to battery -, the larger of the 2 spade connectors is batt +, (if there are 2 large spade connectors look closely one of them will be linked straight to ground, you can usually see this from the outside of the alty), then the small terminal is for the charge indicator light up in the dash, you need to switch this to battery + through a 12v 1.2W bulb when you want the battery to charge, it'd be a waste of power to leave it there all the time, so maybe rig up a relay that closes when the mill is going quick enough to charge.
Some have actually modded a car alty so it starts on its own without the 1.2W bulb, by bunging a magnet behind the rotor, but thats a bit tricky to do.
Some later cars have a silly can bus interface to the alty using 2 wires, sometimes yellow, probably not worth bothering with one of these, even the rev counter works from this.