What do we need this Relay? Why did Hatteras put it there?

[Gusshr]

Why do we need this Relay? Why did Hatteras put it there?

Hi,Troubleshooting alternator external regulator no-charge issue, I am puzzled to see why Hatteras put a relay at this locationositive 32V line goes to one side of the relay awaiting activation through a line coming from pressure fuel sensor that would also carry 32V!?The output of this Relay would send 32 V to the positive side of the voltage regulator of the alternator when the engine is on. I am so puzzled of why Hatteras put a relay there because it is activated when the motor is on buy a 32 V line and when it’s activated it’s just connecting a different 32 V line to the voltage regulator. Wiggling that Relay created a spark and therefore I’m thinking of eliminating this relay completely because there’s really no need for it when the engine is on the pressure sensor of the fuel will connects the 32v to the voltage regulator regulator so I don’t think I need it. Anybody has any idea of why I should keep this Relay? Thank you

 

[Nonchalant1]

It sounds like the engine hour meter sender that turns on the engine hour meter when the engine is running. Don't know why it would be connected to the voltage regulator.

 

[Gusshr]

The hourmeter line also comes out from the same fuel pressure sensor that would carry the 32 V when the motor is on.Additionally people usually put a relay when there is a stark difference in amps or different voltage, but the electric lines are all comparable in gauge nd cary similar voltage here.

Thats why I am inclined to get rid of the relay.

 

[RichardM]

I'm not entirely sure why but here's a theary. Mine is wired like that Too. When cranking the engine, it would prevent the alternator to start putting out power while cranking. Which would be sort of like a dead short for the alternator diodes. Once the fuel pressure is reached, either the engine has started and the starter is disabled or it's at the end of the starting cycle where current is much lower. Sort of a 2-3 sec start delay for the alternator. Plus if you leave your key at the on position with the engine not running, it would prevent energizing the field of the alternator unnecessarily. Just a theory...

 

[Gusshr]

I'm not entirely sure why but here's a theary. Mine is wired like that Too. When cranking the engine, it would prevent the alternator to start putting out power while cranking. Which would be sort of like a dead short for the alternator diodes. Once the fuel pressure is reached, either the engine has started and the starter is disabled or it's at the end of the starting cycle where current is much lower. Sort of a 2-3 sec start delay for the alternator. Plus if you leave your key at the on position with the engine not running, it would prevent energizing the field of the alternator unnecessarily. Just a theory...

That is a great analysis about the delay in activating the alternator. The relay does not have built-in delay, and the delay is coming from the fuel pressure switch so the delay will be maintained if we had the fuel pressure switch to hook directly to the voltage regulator instead of the relay and then the regulator. Also leaving your key on Does not build up fuel pressure and therefore no current will be delivered through the voltage regulator to the alt.