91RRC
A month ago, driving along at night, the lights began to dim. Can't remember if the battery light was on or not. The car was laboring (due to low voltage?) and the wife and I made it to the middle of a busy highway. I would have guessed that the alternator died and then killed the battery on it's way out. Tachometer and speedometer were both working at the time. From the schematics: if the bulb on the instrument cluster dies or does not light, the alternator will not charge.
Put it on and installed a new battery and had the starter rebuilt. Battery light on at ignition and off almost immediately after start. Car runs! Tach does not function. Found another busy highway and it died at a semaphore, the battery exhausted. No light to indicate anything was wrong. Changed battery to a yellow top that works fine in my other Rover (Disco) and alternator will not charge it. Put the battery into Disco and it charged it right up.
Replaced wires and cleaned connections:
+ to starter
starter to firewall
firewall to alternator
- to frame
- to sheet metal and aux wires.
strap from sheetmetal to engine block.
Had alternator tested. I was told that is was not charging the battery. Took battery back to see if it was good. (it was) Had the alternator rebuilt again. (Cooked diodes?) Don't know. Charged battery. Tach worked, things looked good. Wife got a mile away when it died again with what appeared to be a dead battery.
Took the alternator back and had the re-builders check it out. They said it was not generating. Had it rebuilt AGAIN. Tach does not work,
Current Status:

 

Hi their from your battery + to your alternator + you shouldn't see any voltage or very little voltage if your seeing 11.65 you have a wiring issue.
Hope this helps

 

Similar issue today in my 2006 LR3. This morning it wouldn't start, so I jump started thinking the battery would charge, thinking I left a light on or something. Drove to work, tested and started right back u. Checked again at lunch time battery dead again. Had battery tested, battery was good. Tech suggest that the alternator is not sending enough voltage to charge the battery like it should. My guess is the alternator is going bad. I took the battery cable off but it didn't shut off but sounded like it wanted too.

 

Could be the replacement alternator is no good. It takes about 10 min to pull so I would yank it and have it tested. Most auto parts stores do it for free.

 

check your alt output if its less than 13.5 volts its low