Originally Posted by RossB
I have just purchased a 2011 landmark and am heading south in a week, I had a 40 foot travel supreme and I figured I'd try something different. I knoticed when I hooked up my truck the batteries don't seem to be charging off my truck, is that normal ?
Best case you only will get 4 ~ 5 amps of charge rate to the RV on any truck. To get a higher rate of charge you need one of two things to fix this. the length of the wire from your alternator to the battery in the coach is the problem!
We have an inverter and a residential refrigerator so keeping the 12 volt battery charged is very important to us. First thing I installed was a Victron smart shunt battery monitor. Then I could see we are draining the 240 amp hour battery bank below 50% state of charge while towing for 9 hours (with the truck only charge rate). Next I installed the DC to DC voltage booster and now we can keep the battery at full charge as long as the refrigerator doors stay closed and the compressor cycles on and off at a normal rate.
#1 install a 15~20 amp DC to DC power booster , I have a Victron energy Orian smart 18 amp unit that is powered by the 7 way power cord. Any larger then that and you must run a seporate wire and connector. To get 18 amp at 14.4volt at the trailer battery It draws about 25 amps through the 7 way connector. I know there are other brands but Victron is considered the industry gold standard. I know that I am getting a full 18 amps , I can see it on the shunt battery monitor .
#2 Much larger wire from your battery to a Andersen connector and add larger wire to the trailer battery.