Advice on a charge controller please :)

[m_c]

I did just type a big response, but just hit the wrong button, so here's just the summary!

Running a full split charge system will not cost you much on terms of fuel.
Even relying on the vehicle to fully charge the Aux batteries from totally flat, and assuming poor engine and alternator efficiency, will only take around a litre of diesel in addition to what you're taking to drive around. If you use the wind/solar to provide a continual charge, then the vehicle will not see that much of an increased load. Even if the batteries add an additional continual 20A load, it's only an additional 100ml of diesel an hour needed.

As for what split charge system to use, I'd personally build one using a large relay (200A range), and an Arduino.
Programme it so it monitors the vehicle battery, when it hits a set voltage, it connects the relay, if the vehicle voltage then drops too much, have it drop-out until the vehicle voltage recovers then add an additional time delay (will stop the relay continually switching in a short time frame, and give the alternator a rest instead of hammering it continually), and repeat until voltages stabilise. You could also programme it so it doesn't charge the Aux if the Aux batteries are above a set voltage.
That way you should get a reliable system, without the issues with conventional relay systems, and without the over-priced 'smart' systems.


Alsom, if you're van is only putting out 13.5V, then it has issues. It should be above 14V. Is it an old D, or a newer CDI?

[blackburn mark]

I did just type a big response, but just hit the wrong button, so here's just the summary!

owch! i hate that

I am having second thoughts about my tactics (ish)
its an 08 CDI and I measured through the lighter socket with a cheap meter... ill take my fluke out tomorrow and see what It reads at some heavier terminals

I have been convinced that I should be pushing 14.8v into my auxiliaries for at least an hour after they stop drawing lots of current... if I can get anywhere near that out of my alternator ill go with a split and maybe boost the voltage a tad somehow....id have to manually isolate it though... and watch an amp meter for it to tail off... why is shit never easy ? LOL