Just back from a 2 week tour around the West coast and Skye in the van. Only used the hook up once (a day of heavy rain required some drying out of children and clothes!) otherwise used 12v all the way. I'd taken my multimeter with me and this was fine but in the first few days of the tour I thought I'd prefer something a bit easier to see so I could have piece of mind. I'd ran the battery flat by leaving a light on and subsequently blown the fuse a few weeks back and hadn't known about it until stuff stopped working. I wanted to avoid such a situation! Thanks to the wonders of mobile internet I logged onto Ebay and bought one of these whilst camping at Loch Rannoch; http://www.ebay.co.uk/itm/12v-LED-b...?pt=UK_Sound_Vision_Other&hash=item2eb1979361 £12.49 delivered. It was a good job I did it here as I was soon heading into the land of no phone reception (which was very liberating btw!) My wife met us half way through our tour at Arisaig and brought it along. I fitted it there and then and it works a treat. I have one of my auxiliary fuse boxes next to my OG box and a PO had made a hole in the plastic cover for some reason so I just used this to thread the wires through. Connected it to a spare fuse on the box (connected to the leisure battery) and voila! It has an internal fuse but suggest an external 3 amp fuse also. The unit is tiny and is programmable to flash in various ways. I have it so it blinks every second or so showing me the battery status. It basically uses a traffic light system and also shows overcharging etc (comes with very detailed instructions). I can see the unit as I drive along and also when parked up so I always know what's going on with the leisure battery in a subtle way.
I dont like not knowing the state of charge of my leisure battery either, I got a volt meter that plugs into the cig lighter, I can move it, I have one socket on the dash connected to the starter battery and 2 in the glovebox connected to the leisure battery. you could use a switch with that unit if you have two batteries.
I looked at those as well. Look good. Also saw some designed with motorbikes in mind. Single LED which flashes various ways to show various things.
Oh, and yes, I might install a 3 way switch at some point; Leisure/off/Main. As the unit is mounted in the main fuse board it'd be simple to wire it into an existing fuse to also show the health of the main battery.
I fitted a couple of those to our pair of bikes, very good design, guy that sold them to me was very thorough with his instructions. I found them extremely sensitive and not always 100% accurate... but once you understand the flashing code they're ace. *edit* In the van I have a VDO voltmeter in the dash and 3-way toggle to it. Shows leisure or starter at a flick with an off position too
I have a 3 way rotary switch with my VDO voltmeter which does the same but looks more like the original switches
