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Topic: Relay or Mosfet as switch. (Read 706 times) previous topic - next topic

sounduser

Hi,

Im not too sure what I'll need.

Ive added a second battery and alternator to my car. I want a relay to be turned on by the ignition, to switch on the charge/excite circuit of the alternator.

At the moment the excite circuit is coming straight off the ignition, with a charge light. But this is causing engine interference (a whistle) that disappears, if alternator number two is excited by battery number two directly. Thus the desire to have a switch/relay.




If you're not familiar with how alternators works. They need 12 volts to excite the electromagnet that produces power from the motion of the engine turning it.

Thank you

Goofballtech

Why not just get a diode isolator and let one alternator charge both batteries?

http://www.victronenergy.com/battery-isolators-and-combiners/argo-diode-battery-isolators/

sounduser

Ive got everything fitted and wired up almost perfect. Im thinking of trying the kind of relay that are used for heat lights and putting the + through it.

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