chris roberts

Discussion in 'General Electronics Chat' started by roberts, Aug 23, 2009.

  1. roberts

    Thread Starter New Member

    Aug 23, 2009
    i am at present wiriing up my autocaravan with a 240 volt battery charger
    to charge up the leisure battery whilst stationary and also run the 12 volt
    caravan electrics via a 12volt consumer unit. The problem i have is that
    the leisure battery also charges from the caravan alternator whilst the
    engine is running. I need a diode to block the voltage from the alternator
    getting to the electronic battery charger come supply unit. My question is
    what sort of diode do i need, what size should it be and where will i get one
  2. JDT

    Well-Known Member

    Feb 12, 2009
    The trouble with all diodes is that they have some voltage drop in the forward conducting direction. The best sort of diode diode for your application is a Schottky diode that has a smaller voltage drop of about 0.5V (a normal diode is about 0.8 - 1.0V).

    A better method for you would be to use a relay with a 240VAC coil which is only energised when the 240V supply is connected. Use the contacts to do the switching you want. Make sure its a nice big relay with contacts rated 20 - 30A.