Go Back   Jaguar Forums - Jaguar Enthusiasts Forum > Jaguar Models ( Modern ) > XJ ( X308 ) XJ8 / XJR
Sign in using an external account
Register Forgot Password?
Search

XJ ( X308 ) XJ8 / XJR 1997 - 2003

Welcome to Jaguar Forums!
Welcome to JaguarForums.com.

You are currently viewing our forums as a guest, which gives you limited access to view most discussions and access our other features. By joining our community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join the Jaguar Forums community today!


Reply
 
 
 
 
LinkBack Thread Tools Search this Thread
  #1  
Old 01-19-2012, 02:02 AM
Member

 
Join Date: Jan 2010
Location: Ireland
Posts: 50
Thanked 1 Time in 1 Post
Default Accidental reverse polarity while trying to jump start a flat battery

I managed to connect jump leads from a strong battery on a running car with Accidental reverse polarity while trying to jump start a flat battery in the dark on my XJ8.

Hence my year 2000 XJ8 has experienced 12v reverse polarity accross the terminals of an absolutely flat battery. Sparks flew and clearly much energy was exchanged for 5 seconds before I realised.

The car starts and appears to charge the battery. the lights work but the electric seats don't. I will start trying fuses for the seats when I have daylight.


I am worried about diodes in the alternator etc etc . But I am hopeful that the presence of the totally flat battery may have at least partially cushioned the effect by resisting the reverse voltage. Optimism ?


So: How much damage should I expect ???
and Where should I start looking ???


Thanks,

Graham
Reply With Quote
  #2  
Old 01-19-2012, 06:10 AM
Veteran Member

 
Join Date: Nov 2007
Location: atlanta ga
Posts: 2,920
Thanked 526 Times in 461 Posts
Default

Graham:
You are indeed lucky that the battery is intact and the cars seems to run. Alternator diodes would not be my worry, but the ones around solenoids would, I think yo have the right ideav to get it running and check all the fuses. Then figure out what does not work. I know for a fact that many modules are protected from reverse polarity by a diode, which is why the "short the leads together" step in the hard boot instructions usually offered brings a grin to me, although I normally short them myself anyway.
__________________
Ross
MY 89 V12 convertible
MY 99 XJR
MY 02 XJ8
MY 12 XF R
Reply With Quote
  #3  
Old 01-21-2012, 02:24 PM
Member

 
Join Date: Jan 2010
Location: Ireland
Posts: 50
Thanked 1 Time in 1 Post
Smile

I have found one 5 amp fuse blown on the left kickboard fusebox and one 5am fuse blown on the right kickboard fusebox. I believe these were the seat controls. Also one 10 amp fuse blown. I beleive this was the radio.


I have just rememebred the engine bay fuse box and will ventrue there tomorrow IN DAYLIGHT.

The alternator creates 13.5 volts at the battery when the car runs with the totally flat battery. ...so I think my alternator etc is intact.

I have also found a 5 amp fuse blown in the boot / "trunk fuse box. It was on the row nearest the front of the car and it was the fuse closes to the centre of the car.
Question 1: WHAT WOULD THIS FUSE BE ?

Question 2:
Would you still be worried about diodes / Relays or is this all sounding hopeful ???

(I will say a prayer to the god of fuses.)

Last edited by Graham; 01-21-2012 at 02:27 PM.
Reply With Quote
  #4  
Old 01-21-2012, 02:54 PM
Senior Member
 
Join Date: Aug 2011
Location: Chicagoland
Posts: 645
Thanked 50 Times in 42 Posts
Default

Good thing you didn't end up like these guys.

Jumpstart car Fail : theCHIVE
__________________
2002 911tt -Current DD and WW CF Mirrors, CF Ruf Spoiler, GT2 Bumper
1989- Ford Mustang GT 5.8-- far from stock
2005- Triumph Sprint St
2004- BMW r1200c Montauk
1970- Triumph GT6+
1998- Jaguar XJR 4.2 swapped
Reply With Quote
  #5  
Old 01-22-2012, 01:35 AM
Member

 
Join Date: Jan 2010
Location: Ireland
Posts: 50
Thanked 1 Time in 1 Post
Default

Thanks again !!

(I'm assessing whether to just buy a new battery or whether to but a car with blown engine as parts as there's one local right now. Hence would like to test a few things and don't have the ability to just use the car as the old battery is fully flat and concerned about buring out alternator if i run it too long.)

Hence:
Question !:
Is there an easy way to test a diode ??? I have a good multimeter and would be keen to pull and test at least the obvious ones in the boot / trunk and kickpanels.


Question 2: on the left hand kick panel there was a fuse with a yellow protection cover over it. The protector cover gave me the feeling off .... "keep away" and hence I have not tested it. What would this fude be for ??

Question 3:
Is there a way to test the relays and is there any need to test these ??

Graham

Last edited by Graham; 01-22-2012 at 01:41 AM.
Reply With Quote
  #6  
Old 01-22-2012, 03:40 AM
Cadillac's Avatar
Veteran Member
 
Join Date: Mar 2007
Location: Planetarium
Posts: 10,871
Thanked 451 Times in 342 Posts
Default

Quote:
Originally Posted by adam699 View Post
Good thing you didn't end up like these guys.

Jumpstart car Fail : theCHIVE
This is nasty .
__________________

NITROUS OXIDE
Tutte Le Strade Portano A Roma
CHRONOMETRIC PRECISION

If You Drive A Porsche Boxter in Red, You're Unpleasant -Henry Cole
Reply With Quote
Old 01-22-2012, 03:40 AM
 
 
 
Reply



Tags
2012, accidentaly, battery, car, jaguar, jump, leads, points, polarity, reverse, reversed, start, starting, terminals, xj



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Advertising

Featured Sponsors
Vendor Directory
Our Sponsors
All times are GMT -5. The time now is 08:46 PM.

Copyright © 2010 Internet Brands, Inc. All rights reserved.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014 vBulletin Solutions, Inc. All rights reserved.
JAGUAR and its logo are the registered trademarks of Jaguar Cars Limited. Jaguar Cars Limited is not affiliated with JaguarForums.com.