XSeries-forum

I have just replaced the FSR unit and have put some instructions into the how to forum if anyone else needs to do it

Really easy job(except trying to see it) and only took about 25 mins

Will test it again tomorrow to see if the alternator is ok now, don't think it was the FSR though as the one i removed was the new type so must have been replaced before

[quote="Ubatoid"]
[quote="X5 4.6IS 2003"]
Hi
i have tested the car by reving to 2000rpm and pit a meter accros the terminals, i got between 13v - 13.3v with no electric working.

I then did the same but with all the electrics on and only got about 9.8v - 11v does this mean the alternator is definatly  knackered?

Has anyone tried to repair an alternator before as i'm thinking it should be repairable unless the windings have gone.
[/quote]

Those readings are well down. I would expect to see  14 v running.
[/quote]

Yeah i agree, but people have said that a faulty FSR can play havoc with the alternator so thought i would replace as my heating was weak also

Just an update in case anyone else has the same problems as i have, it turned out to be my alternator in the end, i also had a slight growling noise which went after i had replaced the alternator.
Running like a dream now(touch wood)

That's good news you managed together it sorted out, and I guess you're nice and warm with a new FSR

[quote="Ubatoid"]
[quote="X5 4.6IS 2003"]
Hi
i have tested the car by reving to 2000rpm and pit a meter accros the terminals, i got between 13v - 13.3v with no electric working.

I then did the same but with all the electrics on and only got about 9.8v - 11v does this mean the alternator is definatly  knackered?

Has anyone tried to repair an alternator before as i'm thinking it should be repairable unless the windings have gone.
[/quote]

Those readings are well down. I would expect to see  14 v running.
[/quote]

So 13.7 volts (measured across the battery terminals) at 2000 rpm with nothing switched on is too low?

I'd be more worried about 9.8V with the systems running.

13.7 volts is marginally low, but could be explained by a less than perfect volt meter (I assume your just testing with a off the shelf uncalibrated multimeter.

Around the 14V mark should be pretty ok.

With the engine off, there will be an initial surface voltage which can be higher than expected, just run the headlamps for a few minutes, it should drop to between 12.4 - 12.7 volts.. If so your battery should be ok. (assuming no parasitic drain problems).

If the voltage drops too low, the battery's either flat, or has a bad cell.

It's not always the battery though, I had a 3 amp drain from a faulty Alternator on my E34 bmw.. Flat battery every morning. Ironically the car worked great, and the alternator still charged/recharged the battery no problem.. Full voltage with car running etc.. But 12 hours later.. flat .

Between 13.5 and 14.5v with engine running should be ok, it will probably vary depending on the underlying condition of the battery.

Voltage should drop to around 9.5v for a short period after starting the engine. Ideally testing this with a 200amp load for 15 seconds.. Kinda hard without a proper battery tester, as even starting the engine.. its not like it takes 15 seconds to start up

You can also check the voltage on the dash as long as you have the high cluster. Need to unlock it to get the voltage test up.

[quote="X5LeMans"]
I'd be more worried about 9.8V with the systems running.

13.7 volts is marginally low, but could be explained by a less than perfect volt meter (I assume your just testing with a off the shelf uncalibrated multimeter.

Around the 14V mark should be pretty ok.

With the engine off, there will be an initial surface voltage which can be higher than expected, just run the headlamps for a few minutes, it should drop to between 12.4 - 12.7 volts.. If so your battery should be ok. (assuming no parasitic drain problems).

If the voltage drops too low, the battery's either flat, or has a bad cell.

It's not always the battery though, I had a 3 amp drain from a faulty Alternator on my E34 bmw.. Flat battery every morning. Ironically the car worked great, and the alternator still charged/recharged the battery no problem.. Full voltage with car running etc.. But 12 hours later.. flat .

Between 13.5 and 14.5v with engine running should be ok, it will probably vary depending on the underlying condition of the battery.

Voltage should drop to around 9.5v for a short period after starting the engine. Ideally testing this with a 200amp load for 15 seconds.. Kinda hard without a proper battery tester, as even starting the engine.. its not like it takes 15 seconds to start up

You can also check the voltage on the dash as long as you have the high cluster. Need to unlock it to get the voltage test up.
[/quote]

Actually I'm using a recently calibrated Fluke. And also using the dash. 13.8 volts (dash) is the best I see although typically 13.7 whilst cruising. I'm trying to decide if I have a current sucking starter motor, dodgy alternator, or a parasitic drain. Since my alternator charging test seems to be inconclusive (i.e. ~13.7 volts), I guess I'd better rule out a drain issue next.

A fully charged battery with the engine running should show 14.2V to 14.4V on these cars, so 13.8V is low as said but not seriously so. 

Engine off for four hours and car asleep should be 12.6V.  Anything below 11.5 is a problem battery, or parasitic draw, or starter issue though the latter tends to cause system resets when starting. 

Starters are a known issue with some drawing in excess of 900A which exceeds the battery capability and hence a large volt drop which takes time for the alternator to put back.

[quote="X5 4.6IS 2003"]
Thanks horizon, i have also ordered a new FSR as i can hear a very faint buzzing from behind the heating controls when the car is switched off, coupled with no hot air blowing and a rather week air flow so i though best change it,
I will fit that then re-test the alternator just in case is is causing the problems and if still the same i will remove the alternator and test it through a panel
[/quote]

The slight buzzing is a good thing, that should be the tiny fan in the climate control panel. Its supposed to run any time the car isn't in sleep mode. Without that fan the climate control gets very temperamental.

If your battery is low, it could be that some of the climate control systems, and the valves are not being operated correctly, If you have no heat when everything is dialled up to max, you probably have an issue with the valve that diverts heat to the matrix.

[quote="Bargain Bucket"]

Actually I'm using a recently calibrated Fluke. And also using the dash. 13.8 volts (dash) is the best I see although typically 13.7 whilst cruising. I'm trying to decide if I have a current sucking starter motor, dodgy alternator, or a parasitic drain. Since my alternator charging test seems to be inconclusive (i.e. ~13.7 volts), I guess I'd better rule out a drain issue next.
[/quote]

Right. Just measured current drain once it's gone to sleep. ~35ma so none of those pesky parasites sucking precious power from my battery. So either poor charge or dodgy starter.

was it a amp hungry starter in the end?