Tuesday, March 25, 2014

Jaguar battery drain

So you've got a battery drain... well don't feel so bad today and many times I got one kicking my behind too! So today I decide to start this article today and I will improve it and keep adding information as I do more battery drains on these cars and hopefully create a good reference for others with the same problems.

First off this is what the drains are supposed to be according to specifications by Jaguar literature:

  • XJS 3.2L: less than 30 mA after 1 hour
  • Sovereign 3.2L: less than 37.3 mA after 1 hour
  • XJ6 4.0L: less than 38.6 mA after 1 hour
  • XJS: less than 43.9 mA after 1 hour
  • XJ6 (X300) '95 MY: less than 43 mA after 1 hour
  • XJ8 (X300): less than 30 mA after 1 hour
  • XK8 (X100): less than 30 mA after 1 hour
  • S-type (X200): less than 30 mA after 1 hour
  • X-type (X400): less than 30 mA after 30 minutes
  • XJ6 (X350): less than 30 mA after 40 minutes
  • XJ8 (X350): less than 30 mA after 40 minutes
  • XK (X150): less than 30 mA after 3 minutes if locked and after 33 minutes if unlocked
  • XF (X250):  less than 30 mA after 3 minutes if locked and after 33 minutes if unlocked
  • XJ (X351):  less than 30 mA after 3 minutes if locked and after 33 minutes if unlocked

Knowing these is a good place to start, but I learned that they are not very accurate. So (lucky me) there were to XJs in my shop that day, one with the battery drain problem and one completely unrelated. So I was able to test the battery drain on the good known Jag and compare it. So I decided to start testing the battery drain in good known cars for when I have the problem I know EXACTLY how they are supposed to behave. Here are my findings (check back because I am planning of testing hopefully every type of Jag):

I did a battery drain test on good known cars. The way I did it is I unhooked the battery negative side terminal and hooked a DMM in series and press record (my meter is expensive as he** so it can record ok?!) So now with the cars I tested I can tell you what the different current was at different times. I did and will continue to do these test only on cars with no aftermarket equipment. If you have aftermarket equipment then unplug that first.

1998 Jaguar XJ 4.0L N/A
As soon as you hook up the meter you get about 1.9 Amps which drops quickly to about 250 milliamps and remains like that for about 15 minutes. Then it drops to about 48 milliamps in the next three minutes and it drops steadily to about 27 milliamps for the next twelve minutes.

2001 Jaguar XJ 4.0L N/A
As soon as you hook up the meter you get about 1.6 Amps which drops quickly to about 1 amp and then drops steadily for 15 minutes to about 0.8 amps. In the next 5 minutes it drops quickly to about 30 milli amps and stops dropping at 30 minutes.

4 comments:

  1. I just bought a 1998 XJ8. Same issue. Brought car home. After a day or so the battery was dead. Not sure how old that battery was, so we spent $170.00 on a new battery. After a week or so went out to start it and that battery was dead! There are no add on equipment in this car.
    Not sure where to look next.

    ReplyDelete
    Replies
    1. first off im assuming u have no aftermarket equipment. if u do unplug it and see what happens. next is to do a battery drain test with a dmm and see that the drains match the description i typed for the 98 xj8. if u see to much drain then u get a buddy to start removing fuses as u look at the meter. when the draw drops to the specified value that means whatever that fuse powers is the problem

      Delete
  2. It is my ems what could that mean do I have a bad computer

    ReplyDelete
  3. It is my ems what could that mean do I have a bad computer

    ReplyDelete