Battery Light: Alternator Or Battery Or Voltage Regulator?

[sauguest]

Hey All,

I have just returned from a long holiday trip to find the battery was completely flat. Jump started car without issues but noticed the battery light was on

Car = 1999 R34 GTT

So far the checks have revealed:

- After charging the battery overnight, the voltage across the terminals was approx 12.5volts (Car is off).

- Once the car was started, the voltage reached 14.7volts (battery connected)

- Removed the battery while the car was on to check the output from the alternator which was about 15.1volts. (alternator overcharging?)

Help

I don't think the battery is stuffed because i installed another battery and yet the battery light was still on.

I am not sure if its the alternator or the voltage regulator on the alternator... or something else..

Does anyone know where the voltage regulator sits on the R34 alternator? I couldnt see it from the top. Usually you can unscrew the regulator and installl another one.

Is there another way to check if the alternator is stuffed or could it be something else?

Thanks in advance guys!!

[paulr33]

i had this issue in my R33, the battery light stuck on, not sure if the same as yours, but i replaced the alternator and battery and the light was still on

it ended up being a missing fuse in the boot for part of the battery / alternator circuit

i have no idea

how it was missing

what fuse it was

or why its in the boot

but maybe check the basic fuses in the boot

a long shot. from memory i put a ford el falcon alternator on my car as well if thats any help

[sauguest]

Hey Paul,

Thanks for your response.

My guy feeling tells me its a fuse. I will have to trace back along the wires to find it.

The annoying thing with the alternator in the R34 is that it has an internal voltage regulator so i cant even pull this out to check it.

I will look for the fuse!

Thanks man!!

i had this issue in my R33, the battery light stuck on, not sure if the same as yours, but i replaced the alternator and battery and the light was still on

it ended up being a missing fuse in the boot for part of the battery / alternator circuit

i have no idea

how it was missing

what fuse it was

or why its in the boot

but maybe check the basic fuses in the boot

a long shot. from memory i put a ford el falcon alternator on my car as well if thats any help

[paulr33]

yeah from memory mine was the same

i had a friend replace the alternator before hand and then the same problem was present

then took it to auto elec and the car sat at the auto elec's for 2 days while they debugged it

eventually found a missing fuse in the boot

[sauguest]

Good news people

Its fixed.

Took it down to Righton Electrical (recommended by Racepace) in Knoxfield. Nice guys

I couldn't find any fuses relating to the battery in the fuse box or any fuses around the battery/alternator.

And ofcourse being a noob and no time i didnt bother checking all the fuses in the fuse box!!

So turned out, a fuse in the fuse box which is for the horn was blown causing an issue. and voila its all fixed !

Lesson:

Check all the fuses when you see the battery light come on.

Some repairers (i wont mention who) will say its the alternator and that you have to replace it! But get another opinion.

The R34 has an inbuilt voltage regulator (some places may charge u for a new/reco alternator)

Joke of the day:

I asked Nissan (FTG) how much it would cost for a new alternator for the R34.

Response....

$2000!

I just laughed at him and left!

yeah from memory mine was the same

i had a friend replace the alternator before hand and then the same problem was present

then took it to auto elec and the car sat at the auto elec's for 2 days while they debugged it

eventually found a missing fuse in the boot

[PIOTREK]

2 grand maybe with a new engine hahaha

[JamieR]

Funnily enough I have a very similar issue...

I've got the battery on charge tonight so will be testing again tomorrow. It's pretty much a brand new Varta, so struggling to see that is the cause.

It's bizarre though as it was fine one day, then fired up another and hey-ho the problem was there.

Where did you locate the fuse for the horn? I've checked all the fuses in the unit in the driver's footwell and all are fine there, although I did notice one 15A fuse missing, but listed on the fuse diagram on the backface of the fuse cover. Doesn't state what the fuse is for though.

EDIT: I've just found this, so I'm sharing as it's probably of use to some of you amigos on t'other side of the Earth

Therefore I don't have a missing fuse.

If you can advise on the other fuses I'd be very grateful.

Cheers,

J.

[paulr33]

yeah its weird with the fuse problem hey

there are two whacko issues i see on the skyline with fuses

1 is std ecu works when 10amp is missing/dead but powerfc doesnt

2 is battery light remains on when a specific fuse in the boot is dead

[JamieR]

The fuse in the boot was just on the R33 though, am I correct?

If the original author of the thread finds this, it would be handy to know the whereabouts of the fuse he had to change

[paulr33]

no idea what fuse, i think it was one in the boot

[t_revz]

never disconnect a battery on a running engine to test output. alternator cant sense voltage and therefore goes to max and overcharges and destroys electronics such as radios etc.

[08yannch]

no idea what fuse, i think it was one in the boot

alt fuse is in the boot from memory. but from what i have read above any angry fuse can cause problems

never disconnect a battery on a running engine to test output. alternator cant sense voltage and therefore goes to max and overcharges and destroys electronics such as radios etc.

^+1. this has been addressed b4.

the battery regulates the power acting like a buffer and if u remove it. it is very likely u will kill your ECU

concerning alternator. does any1 know of a model of car the has a higher output alt that fits the RB25DET?

[JamieR]

Morning y'all,

Does any1 know of a model of car the has a higher output alt that fits the RB25DET?

I'm afraid I don't pal, but I'd like to confirm that a change of alternator on my car has fixed all problems. Battery light off, sluggish turn over vanished and GT-T performing perfectly once more

[t_revz]

how much bigger do you want and why? you can get a sparkie to change the windings internally and output increases but output drops at idle. did this to my commodore years ago and went from 85 to 150 amp output but the lights flashed at idle when the stereo was on. from memory its a decent size alternator on 33`s already

[08yannch]

Morning y'all,

I'm afraid I don't pal, but I'd like to confirm that a change of alternator on my car has fixed all problems. Battery light off, sluggish turn over vanished and GT-T performing perfectly once more

nice to know ur skyline is fixed

how much bigger do you want and why? you can get a sparkie to change the windings internally and output increases but output drops at idle. did this to my commodore years ago and went from 85 to 150 amp output but the lights flashed at idle when the stereo was on. from memory its a decent size alternator on 33`s already

"well for me" i what bigger because of a 400w RMS a/b amp + 500w rms D class amp = high power demands. and the stock one should be able to handle it as long as i dont crank the system all the time. but i think knowing about alternative alternators would come in handy in the event my alternator shits itself.

[t_revz]

mine has lasted 6 years with 750w rms and 300w rms amps without any dramas. including a drive from perth to gold coast and back with volume on max for complete trip and only stopping for fuel...