So the other day, I left my lights on for several hours. Of course the battery died, so I had to jump it. After the jump, I let it sit running for a few hours and then drove it around. All was working fine. Went out a few hours later and it was dead again. This time, whenever I got it started, it would cut off as soon as I unhooked the jumper cables. So now I'm thinking alternator. I got a battery off my tractor that I charged overnight (it's a 12v car battery) and hooked up and she was running fine. I broke out the multi-meter and I was getting 12.5v+ not running and around 14v running. So I got a new battery and put it in and all is well. But this where I have a question / or maybe someone can confirm for me. If I start the truck and don't hit the gas at all, I get a 12.5v+ reading running. I let it run for about 5 minutes and it didnt change. Once I revved the engine a little, it jumped to 13.5v - 14v. So is this typical that the alternator doesn't kick in until the engine RPM's are above idle? This could be the reason why it would shut off when I removed the jumper cables...it seems to be running on battery power until the RPM's are above idle. Oh, I also checked the parasitic draw and it is around 20 milliamps. Thoughts?

Thanks,

 

The alt will put out more volts at a higher rpm, however at idle when you turn on your lights, a/c etc. it should start putting out more volts.

 

yea even at a low idle there should be a noticble jump in voltage across the terminals from the alternator.

bring it out to an autozone or advanced and have them check it on the car for free. theyll hook up a machine across the terminals and a pickup ring around the alternator wires and test it at idle and at rpm, and the machine will make the call about the alternator. they can also do a simple quick load test to see if you killed the battery while its still in. if ur handy and have a second car, remove the alternator and bring it in for a test on thier alternator/starter machine, its the most accurate way and still free to test!

 

Thanks guys, I appreciate the suggestions.

I guess what I'm asking for is that someone with a DII hook up a multi-meter and check their voltage with the engine off and then with the truck started WITHOUT hitting the gas (mine reads the same). From under the hood, you can then rev the engine and see if it increases (mine goes to 14v). Just want to know if this is typical of the Disco II.

Thanks.

 

I wish I could, but almost 3 weeks later and I still dont have my damned disco from the crazies at the dealer.

 

Aw, man. You took your rover to the dealer?

 

nope, i BOUGHT it from a used car dealer... he hasnt done a single repair on it, nd then I find out the check engine lights not working, and the inspection place printed out 10 codes for me... then i varified at autozone. brought it back to him, has been there 2 weeks now, he still hasnt touched it. read some of my other posts, hes actually on here, the scariest part!