Caravan Battery Charging On The Move

Yes but it's more advisable to go from the starter battery or starter motor.

GT
As mentioned, yes you can, but I do not agree with Olcoolone on this.
Because the alternator is the highest charging voltage point in the vehicle, if you want the highest voltage possible to be applied to long, suitably sized wiring via Andersn plugs to a caravan, then the charge terminal on the back of the alternator IS definitely the best place to have the positive cable attached to.

All the negative wires in the charge line must also have the same integrity as the positive wires, so the neg of the big charge wire is best bolted directly to the alternator case or it's mounting bracket. It seems no one does this, they unwittingly connect it to the battery negative.

Because of loads and length of wiring from alternator to main batteries, to connect the charging supply to the +ve terminal of the main battery may deprive you of a very important 0.5v drop or even more. If you are dragging power off the battery the weak link in the charge/flow circuit is the size of the wiring from alternator to battery.
This does develop more and more voltage drop across it while alt is delivering heavy charge loads.
Unfortunately, most people never think of this alt charge wire at all. Funny that, they think the power comes from the battery. How wrong they are.

After all, we are trying to maximize the charge to the caravan, not provide it with ho hum, possibly sort of ok, she'll be right mate type wiring configurations.

Some people do use the DC/DC multi stage switch mode type chargers, they do a good job.

Although you still require good wiring and anderson connections, you can use a 12v to 240v inverter and have it run a multi stage switchmode battery charger to charge the van batteries. This is not as efficient but does work and you may have these components anyway. Many people have all sorts of reasons for not doing it this way though.

Best of luck sorting out the wheat from the chaff on this. I don't go along with a lot of the normal firmly held beliefs people seem to have and stick to, without due consideration to the way charging circuits actually work

Ross M

Thanks to all those who replied. The reason for my inquiry was that I was contemplating using an Ark Pak aux battery set up. However it `s out put is only 6amps, not enough to charge the caravan batteries as well as the aux battery, so I thought that as an alternative I could charge the van batts thru the alternator.
As it turns out my Waeco 80l needs 7.5 amps, so this idea bites the dust!
Thanks again, Regards G.T.