Using sola battery charger and charging altrrnator.

[Gregory]

I am connecting up Solar panel ,battery charger and a a alternator charging from my motor vehicle to a battery in my Caravan would I have to place a Diod on each + lead from each charging device to prevent any damage to either one of the charging device's.
The car will charge the battery when towing and the solar will charge when free camping and the battery charger will charge when stopped at a caravan park.They are all connected together.
Or am I overlooking something else to prevent damage.
If you see a problem could you advise me how to go about fixing it

 

[MikeMl]

G'day Mate,

Power Schottky (low forward drop) diodes can be used as you describe. It will work fine for the solar panel and the AC charger, but not at all for charging the carvan battery under tow. The problem in trying to charge the caravan battery in parallel with regular automobile battery is that the car's voltage regulator senses the front battery, and throttles back its voltage to keep a constant 14.25V across the front battery. If you put wiring resistance and the forward drop of even a Schottky diode in series with the caravan battery, it will not charge at all.

The solution is putting a diode between the alternator output and the automobile battery/car; this raises the alternator voltage (but not the actual battery voltage, or car's system voltage) high enough to cause current to flow into the caravan battery. In the industry, this is called a "diode battery isolator". Note that to do this right, the voltage regulator still must sense the front battery voltage directly (not it's own output voltage, hard to do on some modern alternators with built-in voltage regulators).

btw, even the AC charger needs to have its output voltage adjusted higher by whatever the forward drop of the diode you are adding.