[bibby]

hey guys,

i did the falcon 110 amp alternator swap and also upgraded all my charging wire and negatives cables with 2 guage cable to help prevent voltage drop and now when the car is on its reading 15 volts of charge is this bad or good?
is it over charging?

any response would be great thanks

Sam

[Blkfxx]

Did you hook up a relay on the sense wire like that diagram I sent?

[bibby]

yup sure did

[bibby]

why would that effect it anyways?

[Blkfxx]

The original sense wire is quite long, so voltage drop is inevitable (which causes the alt to output a higher voltage) The relay bypasses it.

[murcod]

Blkfxx wrote:

The original sense wire is quite long, so voltage drop is inevitable (which causes the alt to output a higher voltage) The relay bypasses it.

A sense wire should have next to no current being drawn through it - so negligible voltage drop. (That's the whole idea of using a separate wire for sensing the voltage.)

[Blkfxx]

It has sorted mine and everyone elses that has had a high charge voltage. Weird.

[bibby]

so is it okay or not?

[Blkfxx]

15v is too high IMO.

Mines charges no higher than 14.5v

[bibby]

what could it be do you think?

[murcod]

Yes, that's strange.

Have the engine to chassis and battery to chassis earths been cleaned up/ checked/ replaced. Perhaps you're developing a voltage drop over those connections?

Also, where is the voltage sense wire hooked up to?

Perhaps try checking the voltage from the alternator's body (use that as your earth) to the sense wire terminal - see what voltage reading that gives you.

[bibby]

yes as stated all earths and charging cable was replaced with 2 guage to stop voltage drop, also the volt guage is hooked up to the battery and an ignition 12v as it is suppose to. i also tried with a multimetre on the battery and same reading?

its a optima d34 battery just so you know aswell

[murcod]

Try measuring between the alternator's metal body and the sense wire terminal on the alternator - see what voltage you get.

[bibby]

why do you think i may just be getting an incorrect reading?

[bibby]

and thats the bottom pin when installed correct?

[murcod]

bibby wrote:

why do you think i may just be getting an incorrect reading?

Measuring at that point will be as close as you can get to reading the exact voltage the regulator is sensing. It bypasses all your wiring loom (ie. external voltage drops) and will give a better idea on what the regulator is really seeing.

[bibby]

and what should that be? 13.6-14.8?

[murcod]

Yes, that's probably a good ballpark figure (high 13v to low 14v range.)

[bibby]

no worries ill be at the shed tomorrow ill test it, what do i do if that reads good?

[JrZook]

bibby wrote:

and an ignition 12v as it is suppose to.

There's most likely a voltage drop where you are picking up your 12V from, thus causing overcharging. Measure the sense voltage at the alternator as Murcod suggested and you will probably find that it will be a volt or so lower than at the battery terminal. In this case, add a bypass relay like Blkfxx suggested

[Reubs]

murcod wrote:

Blkfxx wrote:

The original sense wire is quite long, so voltage drop is inevitable (which causes the alt to output a higher voltage) The relay bypasses it.

A sense wire should have next to no current being drawn through it - so negligible voltage drop. (That's the whole idea of using a separate wire for sensing the voltage.)

The 'sensing' wire to the alternator is fed from the same circuit as the ignition coil and meter cluster, through the same fuse and ignition switch contact. There is a few amps being drawn there, and I'm not entirely sure how the regulator is wired but I thought the field current was sourced from that terminal also.

[bibby]

i have a relay in the system like this but ill do the test on the alternator and if its correct ill check the connections on the relay

[Reubs]

The above diagram has the pin numbers correct but the connection inside the relay is drawn wrongly.

Also don't forget to fuse the wire between the battery and relay.

[Blkfxx]

Reubs wrote:

the connection inside the relay is drawn wrongly.

I drew it pretty quickly, That's my excuse and I'm sticking to it

[got_bar_work]

15v is way to high u will boil the battery.

[murcod]

Perhaps (if the voltage measured directly at the alternator is within spec) all that will be required is to run a new sense wire to the battery positive terminal.

(.... and perhaps check for voltage drops across the earths from the alternator body to the battery negative terminal.)

[bibby]

15 amp fuse from the battery to the relay?
and okay guys ill give it a check this arvo

[want33s]

Sometimes when the built in voltage regulator fails the alt will put out 15+ Volts.

[bibby]

its a brand new alternator still haven't checked it but ill check it today i think it was doing it as my sensor wire was going to the fuse on the charging cable instead of the positive terminal would that cause a difference? ill check it when i get home today

[bibby]

yeah dosent seam to be working must of been manufactured with a faulty regulator so now i gota try and get warranty which i cant see happening urgh