12V stuff, power supply

opus · April 30, 2011, 11:23:39 AM

It seems to me to be the simplest and most straight forward way to get power to everything without constantly charging and drawing batteries.

Jeremy · April 30, 2011, 11:27:02 AM

If I understand your diagram correctly, yes it will work the way you want it to, assuming the assorted devices you are trying to power are connected to ground via various places on the bus chassis, rather than directly to the negative cable / terminal of the battery.

I must admit I'm with everyone else though - I'd have a house battery. Keeping your start battery isolated is sensible (although actually charging it while on shore power is even more sensible), but the logic of not having a house battery escapes me. To me the benefits far outweigh the disadvantages - but then this hobby is all about 'doing it your own way'.

Jeremy

opus · April 30, 2011, 11:35:02 AM

I understand what you are saying. First I have no room for more batteries nor the desire to make boxes and room. We get in this thing, drive to our venue. We turn a few lights on and the webasto when needed. We sleep, wake, sing and go to the next venue then come home. We have nothing else in there that requires power. Sure, if I was going camp in this thin or live, I might reconsider. All it is is a mode of travel and a bed.
I really don't want to leave the batteries in and draw and charge, right? In this case wouldn't it be best to use the batteries just for starting and running stuff going down the road?

Lin · April 30, 2011, 12:11:09 PM

Your start batteries should just be for that. However, I still think you would be better off installing at least one separate battery for the house. It won't take up all that much space. The way you describe your needs you certainly do not need a large bank, but a house battery will give you a lot more flexibility. It can even serve as a backup for your starts and generator. Anyway, nothing you do is final. You can always change or upgrade later on.

opus · April 30, 2011, 12:17:51 PM

How would a house battery give me more flexibility than a 55A power supply does?. I carry a generator and a small gas powered battery charger already.

bevans6 · April 30, 2011, 01:12:31 PM

In your described situation, you don't need a battery at all. You only use the webasto, and maybe a few lights, when you are plugged into outside power, and the webasto happens to need 12vdc rather than 120vac. You're only using it to power up the webasto. If you had a battery, you'd have to worry about it, maintain it, store it, and you don't feel that the added benefit of being able to use the webasto and maybe a few 12v lights when not plugged into shore power is worth the fuss. I get it.

I see nothing wrong with the plan, the wiring diagram, or the choice of power supply. If you ever decide to add batteries, you can with complete ease. You can switch at either the positive side or the negative side of the battery to take them out of the circuit, little to choose between it.

Brian

opus · April 30, 2011, 01:18:49 PM

Got it, glad it makes sense. Well it made "sense" to me, but that can be highly underrated.

gus · April 30, 2011, 04:05:46 PM

A single Gp 31 battery will provide you with a backup in case you find you can't use your gen or it fails for some reason.

This battery is about the same size as some auto batteries and your converter will keep it fully charged.

This is a very inexpensive solution to a real pain in the neck of a problem down the line. Any bus electrical or mechanical system will fail at the worst time.

I've used my two Gp 31s more than once as starting backups when my alt failed. Would have been in a bind without them. I got rid of one of my two 8D starters and installed the two 31s in its place. One 8D is plenty for starting but the two 31s are my backup.