Two DC-DC chargers

I have a Projecta DC-DC charger supplying a lithium battery in my Ford Ranger.
I am setting up a camper trailer with a seperate Renogy lithim battery with a Renogy DC-DC charger. The tow bar is fitted with an ignition supplied Anderson plug.
In connecting the trailer DC charger should I connect to the main vehicle battery (as is the case with the vehicle installation) or should I connect to the ignition source available at the Anderson plug?
Is it likely that the two chargers will interfere with each other?
should I revert the Anderson plug (installed by Ford) to constant supply and pick up the ignition signal from the 12 pin trailer connector?

your advice would be appreciated.

kind Regards.

Is the Anderson plug fused anywhere (if so where and with what size fuse? What cable is supplying it? What model is the dc to dc charger? How many amps total are you going to be pulling from the alternator when both chargers are running at max?

If the cable is rated and fused correctly to supply the charger I would use it

H

Yes, fused and the cable gauge is correct. It was installed by Ford at delivery. M question is really whether I should swap it over to the battery supply. Thanks

Saabpilot said:

Yes, fused and the cable gauge is correct. It was installed by Ford at delivery. M question is really whether I should swap it over to the battery supply. Thanks

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If it’s fused and sized correctly I’d use it.

Is it switched at all? I’d hazard a guess hopefully it only powers up when the engine is running?

The charger needs to only power up when the alternator is running.

Thanks. I agree. The supply is via a high current relay unless I’m missing something, I can see no reason why it needs a direct connection to the battery. It has the advantage of providing a source for the ignition sensor on the charger.

Some vehicles electrically isolate the alt from the battery with the ign switch off through a relay. Others like my honda odyssey have the alt and bat pos electrically the same thing with only a fuse or fusible link between them. My redarc charger is ok with this and switches open the charging circuit once a certain voltage is achieved, IIRC 13+ volts.