Rover wouldn't start yesterday (2001 D2, 124,00k). Wouldn't turn over, just kind of grrrd & tried to turn over a little. OK, must be a dead battery (27 mo. old interstate). Tried to jump start it, finally after a lot of revving from the donor vehicle, it cranked right up & we drove home. I took the battery out ( it was reading 12.1volts) & took it to the local tire/oil change /etc/etc/ store-the only one open on Sun. that carried Interstate (I want my pro rata discount). They checked it, charged it & said it was a good battery. I went home put it back in the Rover ( cleaned the terminals & cables really well & put dielectric grease on both) & tried to crank it up. GRRRR-no start. Lights inside are bright nothing to point to a dead battery. Hooked up the jumper cables again & she roared to life. Shut it off, waited a few minutes, tried again-started right up. Turned on the A/C, radio, wipers , hazards, windshield heater. Everything's good. The tach by the way, was normal, about 800 at idle, revved right up no problem. Shut it off again, waited a couple of hours, started again, no problem. Is this just an anomoly or should I have it checked out further??
I checked the voltage again while it was running & it was 12.84V.

 

Sounds like possibly a starter issue. If there is/are bad spot(s) on the starter, the amperage output from a single battery will cause a no-start condition, but when jump starting, the combined amperage, the current may burn through the bad spot on the starter armature and the vehicle will start.

 

Get a new battery. Voltage should be in the 13.5V-14.5V range.