Battery goes DEAD in Minutes on my 2002 4.6 HSE Rover!

[mictouch]

Hello All... I have a 2002 Rover 4.6 HSE with 77,000 miles and it has a brand new AC Delco Battery. I took the new batterey back to the shop where I purchased the battery and they charged it at 20 amps for 2 hours and load tested it right in front of me at 600 amps and they said it was alright. I took it back home and charged it at 2 amps all night. Got in the Rover and it ran in the driveway for about 3 minutes then drove it down my hill to go shopping and everything electrical went dead, ie, Speedo, Tach, Lights and more. Funny the electric windows worked and the Rover was still running. I turned around to take it back home and this is when I realized it was stuck in something like 3rd gear. Made it back home and the battery is so dead it won't start. I charged it back up and it all sounds good again. Kind of afraid to drive it anywhere... Any thoughts would be greatly appreciated...

[Savannah Buzz]

Battery was not dead, because truck still ran, fuel pump pumped, ECM calculated how many micro seconds of squirt of fuel per cylinder to apply, on and on. You were in limp home mode for the tranny.

What is bad is a connection, or several of them.

Places to look and clean:

Main battery terminals

Other end of main battery negative cable (goes to frame)

Every terminal and big wire you can see in the underhood fuse box. Include the fuse links (bolt down fuse) as well. Normally a fuse link runs a group of components.

Regular fuses might have a crack in them.

This would be a good time to have a volt meter.

[Disco Mike]

How mechanical are you, what is the CCA rating of the battery? Remove the battery, get it recharged and get it to a shop as soon as you put the battery back in the truck. If you let it sit, the discharge on that battery is so bad you may have a really bad short that could burn your truck to the ground.

[threalassmikeg]

When you turn the key on do you have the lil battery light on the ipack.
If it doesnt illuminate, the battery will not charge.
I dont think a 600 cca battery is correct for your application.

[mictouch]

I have a little mechanical and electrical background - I was a mechanic at Beverly Hills Porsche / Audi in the early 80's and since then I design electronic ignitions for racing and I have wired around 50 race cars from the ground up. I know just a little about wiring but this Rover is kicking my ASS...

No lights on the dash. Battery is brand new in August and I took it back to a AC Delco shop to insure it was still okay. All the terminals are squeaky clean and I did add a 4 gauge ground wire from the alternator bracket where the 2 gauge battery negative is located to the ground buss under the fuse panel under the hood. It does have its issues with one window saying "It's Not Set" then another one pops up a day later and then multiple windows come in the act and join in during the ignition key off sequence. Even the sunroof joins in at times and sometimes they all go away on vacation.

When I got the battery back I charged it a bit more per their instructions ay the AC Delco Shop. I check the output voltage with my Beckman Voltage Meter and it only registered 12.1 volts even at 4,000rpm. I drove it for 1 hour today and everything seemed normal with 4 stops out shopping, just 5 minutes after I just left a business I hit the freeway and on the freeway onramp the check engine light came on along with the ABS and the speedo and tach died. I was very close to my friends shop and when I got there the battery registered 7.9 volts. I made it 3 more blocks before it started to sputter and peter out.

I am just guessing that the alternator is giving up... Sometimes it reads 14+ volts output and other times a lot less...

Thanks for all your help... I love the Rover and I hope it doesn't burn to the ground before I get a chance to bring it back to life...

[Spike555]

Yup, sounds like a failing alternator to me too.

[atancreti]

Make sure you don't buy a cheap one from auto zone, or napa ect... They are made with inferior Chinese parts and fail often.

[Savannah Buzz]

Your best bet on the alternator, if it is original equipment, is to have a local shop rebuild it. Probably the voltage regulator module, perhaps a diode. But this can be done for like $100. Or you can oder the parts and DIY. If you buy a reman from any of the national chains, the failure rate is above 50%. Where ever they get their parts they just won't take the heat under the hood.

If it was a diode that was bad, it would show OK voltage at idle with nothing on. But as load increases it would drop, drop, drop.

12.1 volts is a discharged reading for a truck battery. 2.1 to 2.2 volts per cell X 6 cells = 12.6 to 13.2. Charge at 13.8 - 14.2