Choosing your DC charging and split charging system.

Right straight down to it. No waffle.

Here is a wiring diagram of the most basic system. An engine with it's own battery and alternator as it comes from the engine supplier. We have added to it a domestic battery bank

As you can see, the starter motor only operates from the engine start battery and the alternator only charges the engine start battery. Obviously we need to change this to enable the alternator to charge the domestic battery.

The first idea many people come up with is a diode splitter. Often they install one, then wonder why the charging system is such a dismal failure.

So let's have a look at the same installation, modifed with a diode splitter and see what is wrong.