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Discussion Starter #1
Battery light on, dimmer and flickering at idle but very bright while driving. No fault codes indicated. In upper rev ranges, while driving, engine misses a little bit, does not want to accelerate rpm's in the upper range.

Note: All 2000rpm measurements were estimated rpm's, alternator is aftermarket with no tach lead hookup. All were at the same level.
1. Engine off, all accessories on for 30 seconds, then off. What voltage _11.82v_____
2. Voltage across battery at idle (no electrical load) __13.1v__________
3. Voltage across battery at 2000rpm (no electrical load) __14.7v______
4. Voltage across battery at 2000rpm (everything electrical switched on) __11.9v_______
5. Voltage at ALTERNATOR at 2000rpm (everything switched on)__11.9v_________________
6. Voltage drop between alternator body and battery negative (YES negative). Measure at max electrical load and 2000rpm ___48.mv___________ (millivolts please)
7. Voltage drop between alternator positive and battery positive. 2000rpm, max electrical load __1--.0___________
8. Check Voltage drop from Battery Negative terminal to 1st groundpoint on vehicle__13.-16.mv (varying)(taken where the negative cable bolts to the frame, not the bolt itself)____________
9. Check voltage drop from 1st ground point to block_12.8-14.9mv_________
10. Check voltage drop from Alternator Housing to block_4.3-4.9mv_________

Also:
-What are your symptoms: Battery light on, dimmer and flickering at idle but very bright while driving. No fault codes indicated. In upper rev ranges, while driving, engine misses a little bit, does not want to accelerate rpm's in the upper range.
-What have you done to fix it so far: Have just noticed this problem, truck was just returned from Rover shop, had idling issues that were fixed with a used alternator and new coil. Battery and alternator were new from a few weeks ago, trying to fix the idle issue. They were replaced because low voltages were seen.
 

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Need to think about it properly but...

used alternator and new coil
Would be be my first port of call. Do you still have the old alternator?
 

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Discussion Starter #3
Sorry, my mistake. Used distributed fixed my other idle issue. Alternator was brand new.
 

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i installed a brand new ac delco alternator and after a couple days it fried it. I went back to the lucas alternator and have no problems.
the tach connector were it is soldered melted off and the wire came off so the tach died and the bat light came on. after replacement with old alternator the problem went away. if your lucas alternator still works use it...
 

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2010-2012 Range Rover MkIII / L322
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The alternator isn't putting enough back into the battery. I'd also second the alternator and that the cars are brand fussy. If you don't want to pay out on Genuine, then OEM is the only other option really.

What brand is it and what is the stated output on the box?
 

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Discussion Starter #6
I agree, oem seems to always be the better way with Lucas.
When I picked the rover up, it had a GM alternator from the previous owner. The shop I took it to when I was at a loss with idle issues figured it was charging system, so the battery and alternator were replaced. The alt is a 90 amp GM.

When the battery is charged overnight, and the neg lead is detached for a bit, the battery light stays illuminated when the truck is started. What is directly signalling this light to come on now? The alternator worked fine for a little while, and even if it's insufficient amperage, wouldn't it have the light on immediately at startup with the new alternator (which was the same as the old, which never switched on the battery light), rather than taking some time to turn on, and not turning off once the battery is charged up again? Also, why the slight cutting out under harder acceleration now that the battery light is on? I don't know.
 

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Discussion Starter #7
Weird. I was driving it around a bit, and the battery light was on, seemed to miss a bit during higher revs. This was my issue as it's been since I posted this thread.
All of the sudden, the alternator starts whining, and the battery light turns off. No more missing at high revs. The question is: Why? What changed? I have absolutely no idea.
The only thing that changed otherwise was a used distributer, installed to fix an idling problem.
 
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