I have a 2004 petrol V8 RR and for the past 2-3 months I've been chasing an incredibly frustrating alternator/battery/charging problem. I'm really hoping someone can shed some light on this, as I'm completely stumped. It all started with several flat batteries and the occasional battery light. After replacing multiple components and a trip to the dealer I'm still experiencing intermittent charging problems. Most of the time everything works flawlessly, then with no warning the alternator will quit charging sufficiently and the battery will lose charge. Here's what's been done/replaced so far:

- New Interstate battery
- New Bosch alternator
- Replaced FSR
- Completed HVAC drain TSB

So despite replacing/repairing the usual suspect items listed above, I'm still having intermittent charging problems. I actually replaced the alternator a second time thinking that I may have received a defective unit the first time around. I know the charging system is tied to the ECU/BCM, so is it possible that the issue is related to one of these computers? Any guidance you guys can provide would be much appreciated.

I once had a fracture in a battery lead. I replaced batteries etc. I found it by chance, I was pulling at the lead to get at something else and I noticed a light flickered. By pulling the lead just a fraction I could switch all battery power off! Previously..
Vogue SE TD6
Defender 90 2.4
Defender 110 TD5
Vogue 3.5 EFI

Have you checked the condition of the engine earth strap and it's bolted connections?
The earth strap is part of the alternator charge circuit.

I was also going to say that the earth connection could be loose. A dodgy cable is hard to diagnose but could be the case. Discovery 4 HSE
1998 110 TUM HS FFR Hard Top XD WOLF
1982 Series 3 Hard Top

*Gone:L462 D5 HSE LUX, L663 Defender 110 HSE, Discovery 3 HSE, 2014MY Range Rover Sport 5.0 Supercharged AB Dynamic; L405 Exec Vogue SE 4.4, 5.0 Supercharged Autobiography, Defender TDCi XS CSW, Defender TD5 HT, Vogue SE TDV8, Vogue TD6, RRSport SC 4.2V8, Classic 3.9 Vogue Auto, Land Rover Series 3 SWB

I did check the earth cables. In fact, I also replaced the battery earth cable and I even ran a new earth cable directly from the alternator housing to the earth connection on the strut tower. Unfortunately this made no difference. 2004 RR Westminster 4.4 V8
Bonatti Grey/Jet

Does your car have the hidden menu on the display that lets you see the battery voltage when you are driving?
It might be handy if you see it suddenly go from 13 or 14v down to 12v and you could investigate when the fault was active. Previously..
Vogue SE TD6
Defender 90 2.4
Defender 110 TD5
Vogue 3.5 EFI

I just ordered a voltmeter that plugs into the cigar lighter for this purpose. It will be interesting to see how the voltage behaves while driving. The real issue though is the fact that the alternator appears to have a mind of its own and will stop charging for periods (usually at the most inconvenient times). 2004 RR Westminster 4.4 V8
Bonatti Grey/Jet

Don't forget that even though you replaced the alternator doesn't mean that the new one might not also be goosed. It can happen. Discovery 4 HSE
1998 110 TUM HS FFR Hard Top XD WOLF
1982 Series 3 Hard Top

*Gone:L462 D5 HSE LUX, L663 Defender 110 HSE, Discovery 3 HSE, 2014MY Range Rover Sport 5.0 Supercharged AB Dynamic; L405 Exec Vogue SE 4.4, 5.0 Supercharged Autobiography, Defender TDCi XS CSW, Defender TD5 HT, Vogue SE TDV8, Vogue TD6, RRSport SC 4.2V8, Classic 3.9 Vogue Auto, Land Rover Series 3 SWB

Does sound like a bad connection.
Have you checked the integrity of the pyrotechnic charge assembly?
Have you checked the condition of the plastic sleeving where the bolt for the +ve jump stud passes thro the battery compartment wall? They have been known to burn and cause a short.

That's what I thought as well, so I replaced it a second time thinking maybe I got a bad one out of the box. I'm not keen on replacing it a third time - at least not until I understand why it's failing. There seems to be an underlying issue that so far I (and the local dealer) have been unable to identify. 2004 RR Westminster 4.4 V8
Bonatti Grey/Jet

Forgot to mention that I also replaced the battery positive cable, thinking the pyrotechnic charge assembly might be faulty. I also checked the remaining connections at the firewall, rear of engine, etc. 2004 RR Westminster 4.4 V8
Bonatti Grey/Jet

You seem to have done everything.
The alternator should be charging the battery given what you've done.
I would wait until you get your voltmeter and you can see whats going on whilst driving.

Based on some of your comments, I ran a separate wire directly from the alternator lug to the firewall lug. So far so good. Perhaps I do in fact have a break or short in the alternator cable. Time will tell. Thanks so much for all your comments & suggestions. 2004 RR Westminster 4.4 V8
Bonatti Grey/Jet