12v alt to charge 24v bank?

[John Z]

While setting up a house bank solenoid for keeping charged while OTR, it was suggested i should set up a 24v house bank instead of a 12v bank. I have been doing some research and reading on it, and i am starting to see the advantages (i think). But how do i keep a 24v house bank and a 12v bank for smaller items, charged while OTR with my coaches 12 alternator?

[NJT 5573]

I think the advantage is to use 6 volt batteries and have a 12 volt system.

[John Z]

From my reading it appears that it saves a lot to run my inverter off a 24v versus 12v bank. Is it not true if i have a 600 watt, 110v draw on my inverter, that on a 12v bank/inverter the draw is 50 amps; and that on a 24v bank/inverter the draw is 25 amps, and requires much smaller wiring? Can anyone clarify this?

[belfert]

It sounds like your coach is 12 volt.  You are probably are better off with a 12 volt house system if you want to charge from the alternator.  The downside to 12 volt is the extremely large cables necessary if you have a large inverter.

Most of the 24 volt systems are suggested in part because many coaches have 24 volt systems.  This makes it easy to charge off the alternator.

Brian Elfert

[rayshound]

One advantage is the smaller gauge wire. I have converted my entire bus to a 12v system, I  had replaced all wiring and installed a 12v alt.  I also kept the 50dn 24v Alt that powers just the inverter as the inverter draws around 250 a at full load. In a 12v system the wire for the same application would be very large about the size as a water hose!  Ray

[Don4107]

You can put a separate 24V alternator on the engine hooked only to the house bank.  Works if you have the same voltage house bank (12V) too.  Simplifies keeping both battery systems at optimal charge without complicated gear.  Gives some redundancy also. 

If going 12V and 12V I would used the big alternator already on the engine for the house bank which is normally a lot larger and discharged more than the start bank. Use the auxiliary alternator for the start batts.  Requires some careful wiring changes if you are not familiar with this sort of thing.   

An advantage to having the same voltage for both banks is you can use a interconnect to help start if the starting batts are low.  As you said a 24 volt house bank has some advantages though.  My old bus has two 12V banks.  Have not made up my mind on which way to go with the new one but I think it will have dual alternators no matter which way I go.  Something else that the new one will have is an independent start battery for the Genset.

There are many ways of doing this and I am sure other will have a different slant.