My 96 XJR is a bit power hungry. I bought it as a basket case and the next part to tackle is the current draw. When the car is off and just sitting it draws 2.25 amps. I know there will be some current draw for the security system and what not, but 2.25 amps seems high.

Does anyone know what is normal before I start my wild goose chase? Knowing what is normal would be nice so, as I get thing sorted out, I'll know when to stop.

 

My poverty pack 3.2ltr was 0.38amps, and had NO aftermarket elecrickery at all.

Both S Types are 0.41 after the customary 40 minutes sleep cycle.

 

N3yyz_XJR,

A general rule of thumb for modern vehicles is that quiescent or standby current draw should be under 50 milliamps (0.05 amps). The '90s and '00s Jaguars I've measured have drawn in the range of 40 mA (0.04 A). Your parasitic or leakage drain of 2.25 A is enormous and will quickly ruin your battery if it is continuous.

As Grant mentioned, you have to measure the drain after all the systems go to sleep (all the doors closed, all lights off, key out of ignition switch, etc.). The 40 minute wait that Grant mentions sounds right, though I can't recall whether that is the exact time stated in the Workshop Manual or other service literature.

You can usually track down a parasitic drain by pulling fuses one at a time until the drain disappears - that will tell you which circuit is malfunctioning to narrow things down. It may just be that you didn't wait long enough before testing the quiescent drain, but if the 2.25 A drain is continuous it could be something like a dome or trunk lamp failing to extinguish, a relay failing to unlatch, etc.

Cheers,

Don

 

I have a 95 XJR (which I'm parting out) and the PO had jump started the car and connected the cables the wrong way around. It seemed to drain a battery reasonably quickly, and occasionally would act up and go full rich and flood the car and stall it.

Once I replaced the ECU the drain went back to normal levels and it could sit for months and still start.

 

Gotta luv old age, forgot the ZERO.

So 0.036 and 0.041 should have been typed.

 

I sat in a comfy chair, JD on hand, and LONG leads extending from the closed boot lid, and WAITED.

Started at around 5amps, then dropped to 2.38, and then 1.6, then the sleep kicked in, just as the JD ran out.

BUT, if, when sleep mode is reached, and the system senses less than 11.8V it will NOT go to sleep.

Soooooo, the continual issues we read about batteries that are getting old causing all sort of havoc, also prevents sleep taking place.

The numbers above are from memory, and close, coz I cannot find the paper I scribbled the exact numbers on.

 

These may help.

X300 Quiescent Current Drain Jaguars describes a method for tracking down the cause of the current drain by systematically removing fuses and observing the result. X300 Quiescent Current Testing is a Jaguar/Land Rover document showing detials of the shutdown period and current drain for various models.

 

Just for a FYI, it's possible to keep doors and boot open for access during this and other testing by using a suitably sized screwdriver to push in the appropriate latch - emulating the striker plate - and fool the car in to thinking the door/boot is closed.

Use the same screwdriver to pull outward on the latch while operating the door handle or boot release to open.

This is particularly useful for chasing down alarm and locking issues.