5A on alternator sense wire (1 Viewer)

[trr1ppy]

Hi all, I have a 12v HJ47 which I have just swapped out the old alternator and external VR with an internally regulated alternator.
The battery is being charged and the lamp on the dash is functioning as expected but the sense wire is popping 5A fuses on startup. I measured the Amperage across the blade fuse holder and its steady around 5.8A with peaks above 6A. I tried a 10A fuse which also blew so now I have a 20A fuse in there which hasn't blown yet.

From the auto elec's and mechanics I've spoken to they think there should be virtually no current through the sense wire so any ideas why mine does? Also I'm curious why a 10A fuse would blow if I'm measuring 6A peak? My guess is my cheap multimeter is missing what the current is actually spiking to.

Thanks for your help!

 

[lacalvette]

Hi,
Was the internally alternator working properly prior the swap?
You could remove the brush holder and have a look at the voltage regulator, clean all contact.
Like the shop said, I don't think sense should draw much amp.
Could you send your electrical connection drawing?

 

[trr1ppy]

The externally regulated alternator wasn't working and the voltage regulator was aftermarket so I pulled the pin on a new internally regulated alternator.

This is my current wiring to the best of my knowledge I haven't split the loom to trace each wire but the wiring inside the loom looks original and is colored correctly according to wiring diagram inside my manual. I have only added the sense wire with a blade fuse.

The 20A fuse blew on the sense wire when I was driving tonight. I'm going away for work tomorrow and am wondering If I can drive around without the sense hooked up and not do any damage to the alternator or battery?

 

[trr1ppy]

please ignore the bottom image as it is unedited.

 

[lacalvette]

Just an idea, no chance that this Sense wire which blow 20a fuse is the B+ to charge the batterie ?
I can't see why the sense would do that???

 

[trr1ppy]

This is the alternator I'm working with and I don't think B+ would run through the 16AWG sense wire and pigtail without melting it but 20Amps does seem like a lot...

 

[lacalvette]

Sure, the 5 amp circuit is not design to hold more amp. Would be reluctant to run it with a 20 amp fuse as insulation may become damage.

 

[lacalvette]

Just a tough, some alt don't have sense, seem to be internally connected to B+, the regulator must compensate for voltage drop?
Wonder if some alt have both option for S?
And then you would have to remove a jumper if you choose the remote sense?

Could you unhook the the S and see what the alt is doing?

Just an idea...

 

[trr1ppy]

I have been using the alternator without the sense wire attached for the last couple of days and its outputting 14v, alternator lamp turns on when the key is on and turns off once started. Everything seems normal other then the sense wire popping all the 3 fuses I've been willing to try... could the internal voltage regulator be defective and be outputting +B on the sense wire?

I'm not sure what you mean by jumper. Is that a connecter inside the regulator that connects +B and S wires? How would I go about removing the jumper?

 

[lacalvette]

Hi,
I don't know, was just a tough. I wrote that because on some alt S Is internally connected to B+. So I Was wondering that if you connected S to the batteries then the alt use this path to output and charge the batteries .

Without S and if it is not connected to B+, I guess that the alt is always on full charge.
Could damage the batteries on long ride.
Did you notice if the alternator is working properly without the S, not always on full charge...(batteries getting hot)

I was wondering too about the VR being faulty?
Can you contact the manufacturer?
Hope someone who use this alt will chime and help you.