very tough circuit breaker question on Volvo 5.7GS

[bruceb58]

Re: very tough circuit breaker question on Volvo 5.7GS

A current clamp will tell you the average current through a wire(worth looking at). They are typically not good at showing current spikes which is what is tripping your breaker.

I shouldn't have even brought up the EMF. It is not enough current to worry about.

 

[wire2]

Re: very tough circuit breaker question on Volvo 5.7GS

A current clamp will tell you the average current through a wire(worth looking at). They are typically not good at showing current spikes which is what is tripping your breaker.

I shouldn't have even brought up the EMF. It is not enough current to worry about.

No, it's good Bruce, we need all the possibilities here.

Scott, I did forget your fuel pumps, (mine is mechanical) but again, it's not going to create the kind of current spike to trip the breaker. And motors don't create as much of a spike as a solenoid coil.

Some clamp on ammeters have buttons to choose average, instant or peak reading. On peak, it will hold the display at the highest it sees. You may be able to rent one at an industrial rental shop. But it must read DC current to get an actual reading.

AC clamp ons are far more common and *will* show a spike of DC current but not display a proper value. As I mentioned earlier, a hand compass will also deflect from DC current in a conductor.

You may well be looking for a voltage spike though, higher volts means higher amps through a given circuit.

 

[scott76310]

Re: very tough circuit breaker question on Volvo 5.7GS

Thanks everyone for the replies. I think I may have found the problem??? Don't know for sure because it hasn't done it and its such a random problem that it is hard to tell when it is fixed.
When I tested the alternator output it was overcharging. At an idle it was only 13.5 volts and whenever I shut it off and the circuit breaker pops it is always at an idle so that doesn't really make sense, however when the rpm is increased it would go up to 17 volts and it would hit this by 2500 rpm. I think this is as high as it would go though.
The reason it was overcharging is because of the low voltage on the sensor wire of the alternator. Basically the alt has the large charging post that goes to the battery and 2 smaller post. Both of the smaller post where connected to the same wire. One post was the exciter post and the other is the sensor post and the sensor post senses the voltage. The sensor wire is about 2.5 volts lower than any other wire I tested on the boat at any time so when the alternator was at 17 volts the sensor wire was only at 14.5 volts and the alternator thought it was charging at 14.5 volts. Basically there is a poor connection somewhere or to much resistance in the sensor/exciter wire and that throws everything off. All I did was unhook the the sensor wire and connected the senser post to the big post that goes straight to the battery. It is a very large wire going directly to the battery and whatever it reads is what the batteries are at and that to me seems like the best place for the alternator to sense from. Everything has worked perfect since I have changed that. Wouldn't you want the alternator to sense the exact voltage of the batteries not sense off some wire that is who knows how long and goes through who knows how many connections and possibly the voltage gauge and the ignition switch?