Just bought the car 6 weeks ago, the coach battery is not recharging while driving. I'll put test numbers and symptoms below. After some messing around I've decided to:
1) change the relay on the firewall above battery,
2) put in 2 golf cart batteries instead of single coach battery,
3) change the charger (either Progressive Dynamics [PD9245CV] 45 Amp Power Converter per David, or a ProMariner ProSport 20, 20amp, 2 Bank 43020).
My main question is "Where is a switched connector (on/off with ignition switch) that I can attach the relay to." The relay in my car is not stock. I believe the body of the stock relay was grounded to the firewall, and a 3rd wire was attached to a switched circuit. In the picture below there is a purple wire that has been cut off (right arrow). When the ignition is on it is hot, when the ignition is off it is grounded (or maybe I have that in reverse...). I believe this is the wire that once went to the old relay, I know Winnabago used purple wires.
If you take a look at the pic of the relay below, I believe that the relay put in by a PO is wrong or it's wired wrong. It's a 3 wire relay, and is screwed in through plastic, so the body is not grounded. The 3rd wire was hooked up to the neg terminal of the battery. It's a voltage sensitive relay, It says on it: "cut in 13.7V, cut out 12.8V" It was basically closed (current went through) no matter what.
Here's the symptoms and what I've found out, coach battery was dead (11.8V across contacts disconnected):
A) The relay: Engine on, engine off, coach battery connected or disconnected the relay stays closed (current goes through it). The car battery died when not driven for 2 weeks. I assume it was trying to charge the dead or dying coach battery while it sat. Thus a new relay.
B) The charger works; 15+V if the house battery is disconnected, 13.8V with the battery connected. Still, i'd rather have a smart charger. Looks like an easy switch.
C) Coach battery was at 11.8V. I charged it overnight on shore power, and it was up to 13.8, dropping .01 every few seconds when I disconnected a terminal. Wanted to change out the battery for 2 6v golf cart batteries anyway.
D) Car battery is at 12.75V with house battery disconnected..
The parts I've ordered/purchased are:
-2 6V golf cart batteries from Costco
-Stinger SGP38 80-AMP Battery Isolator and Relay from Amazon.com
-Battery box:
http://www.allbatterysalesandservice.com/browse.cfm/4,573.html-2 of Camco 47440 Black 5/16" Stud 18" Long 4-Gauge Marine Battery Cable and Lug Assembly Tinned from Amazon
-E Support Car Battery Isolator Disconnect Cut OFF Power Kill Switch
Haven't ordered the charger yet, but I'll probably get the "Progressive Dynamics (PD9245CV) 45 Amp Power Converter with Charge Wizard" from Amazon for 168.99.