Here is a little backstory.

About 2 weeks ago I noticed my battery light was intermittently coming on. I tested the alternator in my vehicle using a DVOM and found at idle it was not really charging (12.3v). At 2000 rpm it was charging at 13.6v. For the past week the light has not come on at all. Today while I was sitting at a light it stalled out. I barely got it restarted and pulled it over where it died again. I could start it and rev it but it would die again. My theory is the alternator failed and at idle was actually bleeding my battery dry and at rev was allowing it to run.

One caviat, I did smell a really strong running rich smell when I did get it to idle afterwards. I wrote it off to the ignition system failing due to power loss and the cylinders loading up on fuel. Let me know what you think.

TIA

 

13.6 seems low. Both alternators I had charged at about 13.9-14v at idle.

 

And the bulb could have been burned out from flickering on/off, or inside problems in alternator. The alternator is a three-phase AC generator that uses diodes to turn alternating current into direct current, and pass that thru a regulator to maintain the 13.6- 14.8 charge voltage. When some diodes are out, your 100 amp alternator becomes a 66 or 33 amp alternator, and can't keep up with demand. On my D1, with everything on and running at idle, that is about 80 amps. So you have been sucking power out of your battery, and the end result is you have a very dead battery, which can't keep ECU up below 9 volts or so.

You'll want to charge your battery with an external charger (new alternator will charge it up but very slowly), and repair or replace alternator. You can meter the DC volts on back of alternator at the two bolted on wires. Both should have positive volts. One of these wires goes to the underhood fuse box and powers the truck. The other is a smaller wire that comes from that battery warning light. + volts is switch on thru the bulb to "excite" the alternator and make it produce amps.

You can buy new, used from dismantler, salvage yard, have rebuilt by local indy shop, or buy reman unit from auto parts chain. If going the last route, get a lifetime warranty, because the reman units have like a 50% failure rate. Sub of a Saturn or Range Rover alternator, or perhaps others is possible, you may not have the luxury of experimenting time.

 

Thanks guys!

I can get a beck arnley for $223 which is the direction I am thinking of going. I have had great success with their parts. Anyone heard otherwise?

 

Normally I've had good luck with their stuff, but most of my experience was for Japanese cars. It always seems like a gamble with rebuilt alternators on these vehicles, but I've never personally used a beck arnley.

One thing to think about is upgrading to a higher amp alternator. A buddy of mine used one on his RRC. I THINK it was a mean green, but those are like $350. I think I read on discoweb that Will Tillery may also sell high amp alternators. Maybe his prices would be better?

 

I wanted to go that route but thought I had to run a 2 batt setup due to the higher amp rating. Would I need a specific voltage regulator for a single batt system.

 

I got a brand new Denso from British Pacific for $200 which is nearly identical to the Magneti Marelli.

 

You do not need a second battery to run higher amp alternator. The extra amps are just reserved capacity, like the truck having 180 HP (rumours, I'm sure) - you seldom use that much. Or having a 5000 watt generator on a job site to run the boom box radio. Not much load....

 

Anyone have any specific model #'s?
I have been searching but cannot find any.

 

British Pacific AMR4247G
Land Rover parts, spares, Land Rover accessories - Search results for AMR4247G