Hello everybody,

Winter is coming and, with it, the usual issues of more difficult start-ups and weak batteries.
In principle the alternator is designed with sufficient power to cope with the consumption of the various systems and accessories used in our Jags.
At idle though and with numerous systems working, I was wondering if that was still true and if the battery would not pay a toll when driving in demanding conditions during winter.

Do you know the electrical power produced by:
- the alternator (say on a V8 SC) at idle and say at above 1500 rpm;
and the one consumed by (non exhaustive list):
- the engine and ancillaries;
- all external lamps;
- all internal lamps;
- air conditioner and heating;
- heated seats;
- audio system;
- etc.

 

Jaguar thought about this before you did, so the X350 cars have an Electrical Load Management System that sheds a particular load if the total exceeds the alternator output. There are two pages on this in the Technical Notes of 2003.5 but I'm not going to reproduce them here, but essentially, it keeps the essential stuff going and inhibits certain things in an order of priorities. Unfortunately this may not be your order of priority !! Essentially the high load stuff is electrical heating so anything that is heated on the car that is in use is examined by this module to see if it can reduce the load. It also protects the battery from rapid discharge by deselecting features.This could occur if the ignition is on, but the engine is not running but with seat and screen heaters on.

 

Thank you, I did not know that.
Quite clever!
I also understand better why there is never any ignition worsening (kept as a priority) at idle.
I did not find the related technical note (TSB?) but found an interetsting thread on the voltage behavior of XK's-XKR's (2006-2014) that probably have a still improved electrical power management:
https://www.jaguarforums.com/forum/x...rnator-157912/

 

When I attended NP04 (New Product 2004) for the X350 we were told about the load management and the heated steering wheel was one of the first to be 'deselected' from the priority list.

The XJ range Introduction 2004 Model Year is a large file .pdf. I think I uploaded a copy to the large file area and I think I sent a copy to GUS for his site.

350nas_New XJ RANGE.pdf is the file and it is over 11 MB.

The Student Guide for the Jaguar training (NP04) will explain a lot but mine is a paper 3 ring copy.

bob