Charging trailer battery from 7 Blade connector

[XJINTX]

If improper to post here please move or delete.

I have a Jeep Cherokee that when tent camping I pull a small off road trailer.
The trailer has on board water, dual batteries,inverter and charges from solar and shore power.

I want to also charge the batteries from my Jeep while towing. I have setup an isolator and want to fuse at both sides of isolator near battery.

My question is if I use a 30 or even 50 amp fuse is that enough? I know the trailer will not draw a lot of current just charging. BUT asking electrical question: The Jeep side I will hook to battery and fuse before the isolator. On startup and say I have to use my winch there will be a lot higher current draw... does it effect that fuse on the charging side... would it blow every time or does the fuse only see current draw from the trailer.

I know I can unplug trailer if needed to winch but don't want to at each startup.

What am I missing or am I overthinking it?

 

[camelracer]

I would think the isolator should open when the voltage from the Jeep drops due to starting or winching. If it doesn't open you could be drawing power from the trailer batteries under those circumstances. Check the isolator specs to see how it works.

As for the capacity of the fuses they should be sized to protect the lightest gauge wire in the circuit.

 

[ntsqd]

What type of isolator is it?

 

[XJINTX]

I purchased a Pac 80 Isolator. Nothing fancy isolates trailer battery from truck and is activated by an ignition hot 12vdc. Think it will work?

 

[ntsqd]

With only a 10 ga. wire and guesstimating a ~20 foot distance between the batteries you're only at 25 amps max carrying capacity at a 10% voltage drop.

I wouldn't expect it to drop out if there is a high current across it, even if the system voltage drops below it's minimum hold voltage. You might want a manual kill switch in the trigger wire for when you expect high current demands. I would use a SPDT switch and wire it to light an indicator light when the solenoid is turned off so that you don't forget it or find out the hard way that it got turned off accidentally.