charging Travel Trailer's house battery from truck main battery?

[vetto]

1) Best I can tell, the Ram 1500 doesn't seem to have a "built-in" isolator" for the tow power pin, meaning that when I'm parked somewhere for a while with the camper hooked up, truck off, any DC loads in the trailer will draw on the Starting Battery and the Camper's House Battery. The only way to stop this is to unplug the 7pin.
Is this correct?
Does any of you Travel Trailer folks use an Isolator on your rig?

2) Is the alternator a "Smart" or "traditional" alternator?
This matters when trying to recharge the trailer's house battery with the truck.
As I understand it, when truck is running, trailer connected, and house battery needs a charge, a traditional alternator will charge both main battery and trailer's house battery - 14.2V from the alternator pumping electrons and not caring.
However, if the alternator is a "smart" alternator, when the main battery is full, the alternator will shut off. This also stops the charge on the trailer's house battery, which could leave it not full.
Anyone know how to tell? Is the voltmeter check on the main battery a reliable indicator? (12.5-13.5VDC = smart alternator / 14-15VDC = traditional alternator)

 

[SnowBlaZR2]

Yes, my camper's charging system draws from the truck battery when it's plugged in.

Does your camper have a battery disconnect switch? Our charging system is set up so that the battery is charged from shore power whether the switch is off or on, and only charges from the truck when it's on.

 

[Richard320]

What you want is something like this. It sends juice to the trailer battery while the system is charging, shuts it off when the voltage drops. https://www.etrailer.com/Battery-Charger/Redarc/331-SBI12.html

 

[Vicdog]

My 2021 seems to stay around 14.5 v. Never seen it much lower. Don’t think it’s smart. My Silverado would drop to 12 some volts With the smart alternator. I use a renogy dc to dc charger. Keeps the battery charged much better than just the isolator.

 

[vetto]

Yes, my camper's charging system draws from the truck battery when it's plugged in.

Does your camper have a battery disconnect switch? Our charging system is set up so that the battery is charged from shore power whether the switch is off or on, and only charges from the truck when it's on.

I honestly have no idea how my battery disconnect on the trailer is wired, because I haven't looked yet. We just got it this past fall, took it on one long trip, and then put it in the shop for warranty repairs. As soon as I get the trailer back, I will be tearing into the 12V system to create a power diagram.
What i do know is that there is three positions on my disconnect, on/off/disconnected, but right now I have no idea what is tied in where.

 

[vetto]

What you want is something like this. It sends juice to the trailer battery while the system is charging, shuts it off when the voltage drops. https://www.etrailer.com/Battery-Charger/Redarc/331-SBI12.html

... I use a renogy dc to dc charger. Keeps the battery charged much better than just the isolator.

If the alternator is "dumb" I cant tell the difference in basic function between the smart-isolator and the dc charger.

If the alternator is "smart", then the DC Charger seems to be the proper choice, however installing it would seem to be a huge challenge. The smart-Isolator looks like a simpler installation, but in this case, it doesn't seem solve the problem of the alternator shutting off and leaving the trailer house battery still in need of charge. "As long as your vehicle is on and the alternator is supplying power to the start battery, the Smart Start will transfer some of that power to your auxiliary battery."

Guess I need to figure out the alternator before deciding.

 

[Trooper4]

I honestly have no idea how my battery disconnect on the trailer is wired, because I haven't looked yet. We just got it this past fall, took it on one long trip, and then put it in the shop for warranty repairs. As soon as I get the trailer back, I will be tearing into the 12V system to create a power diagram.
What i do know is that there is three positions on my disconnect, on/off/disconnected, but right now I have no idea what is tied in where.

Usually a battery disconnect in a trailer is so you can shut down the house batteries for storage.

 

[BK1]

If the alternator is "dumb" I cant tell the difference in basic function between the smart-isolator and the dc charger.

If the alternator is "smart", then the DC Charger seems to be the proper choice, however installing it would seem to be a huge challenge. The smart-Isolator looks like a simpler installation, but in this case, it doesn't seem solve the problem of the alternator shutting off and leaving the trailer house battery still in need of charge. "As long as your vehicle is on and the alternator is supplying power to the start battery, the Smart Start will transfer some of that power to your auxiliary battery."

Guess I need to figure out the alternator before deciding.

Hey Vetto,
Did you ever figure out a way to determine if you have a smart alternator? I'm planning to install a DC-DC charger and am wondering the same.
My truck is 2018 Ram Ecodiesel.
Thanks.