My fiver was supplied with 2 x 110 amp/hr batteries linked in parralel. When on EHU they charge as they should. However when at home and not on EHU they lose charge over a 4 week period, mainly due to a proactive tracker system fitted. Could I expect to boost the battery charge condition by hooking up the TV and running for a period, and if so, for how long. Hooking up to the house mains is a possibility, but requires about 60 feet of cabling.
I believe that using the tow vehicle to charge the 5th wheel's battery isn't very effective unless you run the vehicle for hours.
The length and size of the wires and the connections all cause resistance and at idle the alternator only puts out mimimum amperage. Some have used jumper cables between the batteries in the truck and trailer but that could lead to other issues.I would plug the trailer into the house even though you need a long extension cord.
I recommend you install a battery disconnect switch (simple knife switch) as long as you go into storage at home with full batteries. No need to recharge during up to a four-week period, IMHO. Remember that your CO2 alarm will be sucking juice, too, while the batteries are connected.
2002 Keystone Cougar 286, 8,400lbs loaded, pulled with a 2004 F150 Supercrew, 5.4, 3.73 gears. Retired and enjoying life
If the proactive tracking system is wired direct to the battery, which in my opinion it should be, then you can do as suggested above and use a battery disconnect to remove any drains in the trailer but still leave the tracking device operable. Might gain some more time that way. Or spend a few dollars and get a solar charger and mount it either on the trailer or close to where you park it so you can hook it up to charge while parked.
2008 Dodge Ram 2500 Diesel
2009 Open Range 385RLS
Pull-Rite Super Glide
Thanks for your answers. I put a meter across the batteries this morning, they were down to 12.4v after being parked for 15 days. I ran an extension out and have had it on EHU for 5hrs. Its now dark and after 10pm, so I will check voltage in the morning.
Thanks for your observations and ideas they are much appreciated