The wiring to this fridge is limited in its ability to deliver current,(just too small). If the battery is discharged enough you will get the result you see due to voltage drop. Drive for a while and you should see the voltage rise as the battery charge increases. Of course make sure you have a healthy battery. The source for the relay actually comes from the fuse box so there are a lot of places for voltage drop. If you really want to get the auxiliary battery charged quickly you need to do some upgrade work. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of J Stewart
Sent: Sunday, December 12, 2010 6:41 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Weekender Second Battery Question

Good Morning Folks,
I'm trying to figure out how the second battery set up works in my '85 Weekender. When I bought it there was no battery under the drivers seat. I just installed one, and even though I sold off the fridge unit, I'd like to use it to power other things. I got some time to play around with it yesterday, and with the engine running, at the relay under the drivers seat, one lead was showing 13.94 volts (so that one is coming from the engine battery) and the second battery lead was showing 12.51 volts-shouldn't the second battery be charging when the engine is running? It doesn't seem that it is. Or does it need to drop to a certain level before it starts charging? TIA, Jeff

Jeff Stewart