Hi
I have read all the posts I can find regarding battery drain in an attempt to solve a problem on my RR Vogue 2008 tdv8. i've been left with an almost flat battery 3 times in the past 3 weeks so bit the bullet and installed a brand new Bocsh 110amp S5 a few days ago. After checking the new battery was charging OK, used a Gunson meter and found that there was a continuous parasitic drain of 700 milliamps (enough to brightly light a 12v bulb). After pulling every fuse in turn (almost 100 in total) to try and isolate the leakage, I am no further forward. Every electrical facility works fine when driving including aircon, blower, suspension, A/V, etc etc. I understand that a faulty diode in the alternator could be causing the drain when parked even though its giving a 14.6V reading at the battery when fast idling. Has anyone experience of a similar fault before I start shelling out for a new alternator? I note that one member in particular solved his problem by fitting a new FSR but as the aircon/blower works fine throughout the range I feel this is not the problem - or am I missing something?
Incidentally, after fitting the new battery I put the old one on test and found it to be in excellent condition and holding a no load charge of 12.8 volts. Any help/suggestions gratefully received!

I think you will find that the FSR could be seen as working fine but still be the cause of the drain.

I would change it.

A faulty FSR draining current whilst the car was asleep could well be your problem. Even with a current drain they can work perfectly and show no signs of failure. Unfortunately they don't seem to be testable for faults.
You can test the drain to earth thro the alternator by disconnecting the heavy brown cable from the battery to the alternator making sure its at a point where nothing else is connected to the alternator end of the cable and connecting an ammeter with a scale 0-1A across the gap ie one end to the cable you disconnected and the other end to the point you disconnected the cable from.
Your ammeter should read zero if it reads 700mA the alternator is your problem.

And make sure the ODB port in the drives footwell is closed - this was the source of one battery drain issue on here! 2007 Zermatt Silver TDV8 Vogue SE - now sold but was a great car!

Thanks for all your suggestions. Will be checking the alternator tomorrow and ordering a replacement FSR if no fault found. Any idea where I can source a genuine FSR?
Yes I already checked the OBD cover was shut but thanks for the reminder.

FSR from Dan@Duckworths..... site sponsor.

http://www.fullfatrr.com/forum/duckworth-parts-vf24.html

Ask via a new topic or send him a pm.

I too had a dead battery after a number of "leave the boot open" moments !

I have since changed battery and replaced all internal bulbs with LEDS'  Is this where I put the car details and a bit about myself ?........

Definitely change FSR before doing anything else. Like you, I replaced the battery first with a recommended one from a battery specialist, but it made no difference and I believe to this day it was a brand (Alphaline) and it just wasn't up to the job. Your choice of Bosch was the right one.

Forgive me for asking, but I assume you did your parasitic drain test after waiting for the FF to "go to sleep" (at least 20 minutes after taking key out)? If not, you'll start off with a reading of over 600mh (I did) and with the glove box open whilst you're carrying out the test you'll get a constant drain from the courtesy light bulb in the glove box itself. So you need to remove that fuse to isolate it. I did at least 4 parasitic tests and the lowest reading I could get was 200mh.

Not everyone on this forum is a believer that the OBD flap being open causes battery drain, but Stan told me to check mine (top man that Stan!). It was open and when I closed it the reading went down to under 100mh. Because I had no confidence in the new Alphline battery, I re-fitted the old Exide one (which was still in the garage and holding it's charge ok) and touch wood I've had no problems in the last 2 months! Even started first time after being left for 10 days whilst on holiday!

So I am convinced it was the FSR that was at fault all along. It's cheap at less than £40 and it's a DIY, if not fiddly, job. I'd be surprised if you still have problems after that. I also got my FSR from Dan (don't risk buying from ebay - there are a lot of poor quality ones for sale on there). Price here (although this was in June, so may have gone up a little):-

http://www.fullfatrr.com/forum/topic19282.html

HTH  Cheers

Greg

Go ahead punk, make my day........

Previous vehicles:-
Far too many to list (in excess of 45!)

Update - further checks done today.
After removing ign key, waited 20 mins then connected meter between -ve battery and earth - still showing 700Mamp drain. Removed FSR completely to no effect. Removed cable between starter solenoid and alternator to no effect. Not sure if this latter test was any good as could'nt get at the alternator properly to remove the right cable and check whether regulator/diodes OK.
Now ordered replacement FSR from Dan (£36 inclusive) and hope to refit before this weekend.
Any further thoughts from anyone?

Removing the heavy cable between the alternator and the starter solenoid isolates the alternator.
The fact the current drain measured battery -ve to earth stayed at 700mA indicates to me there is nothing wrong with your alternator the current drain is elsewhere on the car.
It's still worth waiting until you get a new FSR fitted before venturing further.
You don't live near any radio transmitters do you?
It's quite a drain 700mA, 8.8W you'd think something would be getting warm somewhere.
Definitely no light bulbs on in the car anywhere when it's asleep?

Alternator!

Hi Wealy
That was a very positive reply - do I take that you have had a similar problem?

Yep
Been through this pain threshold a couple of times now.
If you have fin the parasitic test with no conclusion it has to be the alternator.
I would disconnect the alternator before you start pulling fuses!

I went around in circles with my car and only when I changed the alternator (for a new one, as i had a local shop recondition it with new diodes and rectifier etc) did I cure it!

It cured a couple of other issues too!

Compressor and radio problems!

Oh
And an alarm problem

Not forgetting I had bought a new battery prior to this and my old one was probably ok?

Thanks for that. If new FSR doesn't fix it then it will probably be a replacement alternator (under warranty all being well)