[mordzy]

Hi all.

Just come to wire up my alternator with a lucas type 3pin plug. Have connected the two larger connectors back to the +12v on the starter. On cranking the ignition fuse blows (30 amp.)

I have disconnected and run the engine and checked the output with a meter and it's 18.4v is this correct?

Any ideas why it's blowing fuses?

Engine is 3.5v8

Thanks

 

[oxides]

Which fuse? That voltage sounds a bit high, should be a little over 14 volts but there isn't a fuse between the alternator and the battery to blow.

 

[mordzy]

That's what I thought.

Inherited DIY wiring... I'll have to pull the dash out to work out the connections for this fuse. Once it's b blown I get nothing ignition wise such as fuel pump, power to coil etc. it does still crank though.

Is the voltage dangerous though

 

[Brown]

That's what I thought.

Inherited DIY wiring... I'll have to pull the dash out to work out the connections for this fuse. Once it's b blown I get nothing ignition wise such as fuel pump, power to coil etc. it does still crank though.

Is the voltage dangerous though

Well, it won't kill you but it might over-stretch a few components on the car, such as that fuse. What's the history of the alternator? If it was new I'd take it back if I was you.

 

[Oldseadog]

If you are measuring the voltage on an opoen circuit you will get a higher reading than if the alternator output was connected to the battery.

The two large spades are linked together, and usually one goes to the starter solenoid and the other to the battery.

The smallest spade will go to your igntion light.

There should be no fuses in that circuit.

 

[timtheenchanteruk]

where is this ignition fuse?
is it one in the fuse box under the bonnet (ie a maxi fuse) because it sounds like it to me, and if thats the case, it should be a 60A.

 

[oxides]

What vehicle is this? says 2a on your profile. If it's anything like a S3 the only things that are fused are the lights, gauges and wiper.

 

[Datatek]

Hi all.

Just come to wire up my alternator with a lucas type 3pin plug. Have connected the two larger connectors back to the +12v on the starter. On cranking the ignition fuse blows (30 amp.)

I have disconnected and run the engine and checked the output with a meter and it's 18.4v is this correct?

Any ideas why it's blowing fuses?

Engine is 3.5v8

Thanks

Shouldn't be above 14.8 volts and running with no battery connected can destroy the regulator.

 

[mordzy]

It's an open circuit, as in meter on the spade connector and alt casing measures 18+ volts. It's not a new alt. came with the engine I'm fitting so don't know it's history other than it's from Hobson industries

Both large spades are connected together and to the starter solenoid.

Fuse wire is aftermarket by previous owner, not sure where it connects yet. I could try a 60a fuse but the wire would be about as thick as the fuse.

Vehicle is a mixed mess of all sorts. G reg 90. Frigged up defender parts. Rr v8 3.5

 

[Brown]

That 18 volts sounds a bit high to me. Other components won't be happy so I'd try and find another suitable alternator that delivers the appropriate voltage. As above, many regulators don't like being run on a completely open circuit. In this situation I've rigged myself up a temporary 'load' (a headlamp bulb and a couple of bits of wire) to give it something to do whilst it's spinning.

 

[mordzy]

That 18 volts sounds a bit high to me. Other components won't be happy so I'd try and find another suitable alternator that delivers the appropriate voltage. As above, many regulators don't like being run on a completely open circuit. In this situation I've rigged myself up a temporary 'load' (a headlamp bulb and a couple of bits of wire) to give it something to do whilst it's spinning.

Thats a good shout. ill run it again with the bulb on and check the load. also need to work out where this wire is going to and from. I have a spare alt but its a right hand one. not sure if i can slacken the bolts and rotate the housing.