Jump start major question:2002 RR 4.6 P38 - Land Rover Forums

RROJ · #1 07-03-2011, 01:42 PM

Someone once told me that these vehicles are wired opposite from U.S. cars. positive is where our neg is and neg is where our positive is. I did not believe or think about it until today. I need to jump start my RR and would like to jump it like a U.S. car. I know its a strange question but do RR have the same set up as American cars? I will not jump until I hear from the knowledgable people of the forum. I left the key turned on due to using the cig light for compressor to pump up a tire and got distracted. ugg!
Thanks in advance.

Rovin4life · #2 07-03-2011, 04:25 PM

first off, is the door unlocked and is the alarm deactivated. if its not then you have close the door by pushing the latch in and pushing down the passenger side bonnet switch and then jump the vehicle. any other way and the vehicle goes into alarm mode and wont work.

but its not opposite, or backwards. its positive for positive and negative for negative. And don't listen to the person that told you the other advice for now on.

Mrmerlin · #3 07-04-2011, 08:15 AM

I think your asking about if the vehicle has a positive or negative ground.
the answer is it has a negative ground,
so the black wire - of the jumper cables connects to the chassis.
the red wire + connects to the hot post or stud .

This postive ground thing was from the early 60s English cars,
and has been changed since to be negative ground in virtually all vehicles from the 70s onwards

RROJ · #4 07-04-2011, 08:52 AM

Thanks guys. i never had to jump her before and wanted to triple check before I did any damage.
Last question. Once its jumped does the battery have to be taken to the garage and put on a slow charge (6-8 hrs.) for it be fully charged. i heard this for the first tme yesterday and need someone else to confim this belief. "jumping a battery leaves it partially charged enough to get you home but it then needs a slow charge to reach its orginal state"????
Any clarification is most appreciative.

LRScott · #5 07-10-2011, 01:09 AM

Go get an automatic charger and let it charge the battery. I will usually put it on a 6 amp charge or 12 amp if I am in a hurry. When it is done, it will turn off.

RROJ · #6 07-10-2011, 09:16 AM

Before I read your note Scott I had purchased a "jump box" and a "battery tender." I plan on jumping the RR and then going for a 1/2 hr. ride bring it home and put the "battery tender" on it until the battery is up to 100% . If this does not work I will open the ole wallet and purchase a new Interstate battery to replace the AC Delco that is currently in there. Any thoughts on this by Scott or anyone feel free to comment.

LRScott · #7 07-10-2011, 12:48 PM

A tender should work fine. It will probably charge the battery a bit slower though.

Disco Mike · #8 07-11-2011, 07:25 AM

A new 800 CCA battery will work even better, bet your's is dead.

RROJ · #9 07-15-2011, 12:24 AM

Hey DiscoMike or any member,
If I bought a 800cc batt. and left my lights on all night would I be able to jump it in the morning run the RR for 20 min then put it on a batt. tender until the indicator light on the tender showed fully charged would it be just as good as a batt. that was purchased?????
Or once a battery is completely dead from a human mistake it will never ever be the same/strong again?

Mrmerlin · #10 07-15-2011, 07:03 PM

If you run down the battery dont use the alternator to recharge the battery thats not what it is made to do.
You can usually cause other damage to the alternator by doing this ,
usually you will fry a diode, then the alt wont put out its full current,
then the battery will slowly go dead as it wont be receiving enough of a charge to recover .

If you do a check of the charging system with a good battery you should be seeing about 14.2 or so with the engine running at about 1500 RPM,
if the alt has a bad diode then you wont see more than 13.4 Volts.

In short if you discharge the battery then recharge it with a charger, a jump start can also fry the BCU computer with a voltage spike, so that should only be used as a last resort, and running the engine with a low battery can kill the alternator.

If you have an older battery then it may also be wise to replace it with a fresh unit.

If you dont follow this advice then things can get very expensive quickly