Hi I would like to set up a dc dc charger to van my current set up is

Vehicle is a 2017 dmax running a redarc 25 amp dcdc to 120 amp agm duel battery running a 65 litre fridge freezer works great

Van has enerdrive 60 1600 watt inverter 2 x120 amp agm and 2 x 160 watt solar panel 2 way 195 fridge freezer

Would I best wire directly from start battery or alternator, through Anderson plug then to 40 amp dcdc charger redarc or enerdrive charger close to battery then  wired directly to battery.The distance of cable is approx 11 metre all up and what size cable would best handle voltage drop .I also have a honda 2.2 generator but just want to cover all bases any extra info from someone who has a similar setup would be greatly appreciated I mainly free camp and rain and clouds seem to follow us and when its to hot I'm looking for shade.

Cheers

You put the DC-DC charger near the batteries being charged. I take it 11 metres is one way, so 22 metres for + & -

travelyounger wrote:

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[deletia]

Would I best wire directly from start battery or alternator, through Anderson plug then to 40 amp dcdc charger redarc or enerdrive charger close to battery then  wired directly to battery.

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 Yes.

This is a similar setup to what we have. The DCDC charger close to the battery is an effective way to overcome voltage drop in the, sometimes long, journey from alternator to camper / caravan battery.

Thanks for the info everyone

Cheers 

An issue with DC - DC chargers they don't have any inbuilt delay mechanism after the engine starts or the ignition feed switches the DC - DC charger on.
Is well recommended you use a battery isolator like a Redarc SBI-12 or similar to let the vehicle systems stabilise prior to dropping the load of the DC - DC charger directly on to the alternator. We do find high alternator failure and other vehicle electrical issues because of this. Battery isolator will only connect the DC - DC charger once the battery voltage gets to 13.7V and generally give a 30 to 60 second delay to let vehicle systems stabilise.
This YouTube vid is on the money https://www.youtube.com/watch?v=EcVjPap9dkY
Was only sent it yesterday by somebody that suffered alternator failure caused by a DC - DC charger connecting directly at vehicle start up.

My car is charging at 80amps instantly after starting then drops to 50amps after about a minute. Without other loads.

I have two 9amp Victron DC-DC chargers in parallel (do as many as needed). As it's only 18amps I run it through a car's circuit, 60amp fuse. Typically both in total are only charging at 7 to 12 amps depending on the state of the batteries, & about 3 amps when charged. DC-DC voltage set to 13.87 volts. The car's voltage in 14.4 volts. So I'm actually dropping it back a bit. If I increase voltage the DC-DC output current is higher.

Most of the time there will be a far lower current than the rating of the charger. Use decent gauge wire so you keep losses at a minimum on your setup. I'm using 6awg wire & my runs are short & lower amps.

Another thought is to get a 12 to 24 volt DC-DC charger & run it into the MPPT controller as it has a great charging profile. Mine has 20amps maximum output.

My Victron MPPT controller has a delay as it calculates the state of the system when it turns on. So this could be useful when starting the car.