Not using the XK much and the quiescent load on the battery is relatively high so wondered if disconnecting the battery between uses would upset the ECU need an EKA code etc.

Many thanks in advance

 

You would probably be better off by plugging in a battery tender on the car....

 

A battery tender is an American term I guess we would call it a float charger. Dont want the car plugged into the house when not in use.
Still interested to know if its ok to leave the battery disconnected and have the ECU come back to life

 

I keep my batt disconnected winter time, approx 6-7 months/year. No problems so far.
I guess keeping battery disconnected long enough counts so called 'hard reset'.

Windows will lose their memory and afaik original radio (I have aftermarket radio), seat memory maybe.
Also transmission most prob loses its memory and it takes a bit of time it to re-learn.

There is threads about battery disconnection somewhere here.

One note about windows:
- remember to open them bit because automatic lowering when door is opened wont ofc work after disconnect. Otherwise you could end up ripping window seals when opening/closing door.
Also remember not to close trunk after disconnect for obvious reasons (I put big bolt to trunk hatch which prevents it to be closed accidentally)

 

There’s nothing to be concerned about if using a battery tender in good condition . The current flow is extremely low. The battery tenders will automatically shut off and on as the battery reaches 100% capacity. Zero fire or safety hazard.

yes , the ECU should come back to life, but I’m not tempted to test that supposition.


Z

 

I think disconnect on the battery means no CA smog test possible until you've driven far enough to record emissions info again.

 

I have 7 cars and two drivers so I often disconnect the battery in some of my X308 sedans.
The engine will rev over 2,000 RPM when first starting after reconnecting the battery but sometimes you can turn the ignition switch to ON and work the throttle pedal.
Shut the key OFF and back ON. Then start the engine and it will usually NOT REV the dead cold engine.

I get a little worried about an engine that has been sitting for a few weeks and when started, immediately revs to over 2,000 RPM.
I like a little oil flow before spin a dry crankshaft at higher rpm.

 

Everyone has been very helpful so fitting a cut our switch will be ok for the 4=5 days I need if off .
We dont do a smog test quite like the US so I dont think its a problem

Thanks, everyone ..

 

Pistnbroke,

You didn't mention why you want to disconnect the battery. I presume you're in the UK, so if it is for long term storage over the UK winter there are some other things to think about - ie our fuel pumps are known to die during hibernation if not used. (The XKR has 2 and the second pump is rarely used, so Forum members here have seen the second pump die and they didn't know it). There is also washing the underbody prior to storage for rust prevention. Super long term storage will need fuel stabiliser added to the tank, plus things like putting paper under the wipers, covering the exhaust tips, etc. Some people even jack the car up to take load off the suspension - (personally I don't think that's necessary).

If the car is garaged there are other things that can be done easily to make the car more reliable on re-start up (I presume for the UK summer). The battery tender is a very simple addition and I strongly recommend that. Batteries will go flat even if they are disconnected, and then it's hard to bring them back to 100%. Also when you re-start the car, disconnect the starter relay, and turn the crank over to pump oil around the engine first - then you can start the car.

Lots of threads on this forum, of people storing the X100 in really harsh conditions. I remember 1 member even built a purpose made shed for his car for the deep winter snow drifts of Canada. Look these threads up for ideas, as they even mention an optional engine block heater!

As like other people in this forum, my Jag now sometimes sits unused for months , so I did plan for it. I've put in fellow forum member Rothwell's fab idea of a little data panel in the trunk and so at a flick of a switch I can easily check the battery voltage. Plus I have an easy access to another 12V cigarette lighter socket to plug in an old fashioned battery tender/maintainer (which has the auto off function). Pictures are below. In my eyes why take the risk of fully discharging old capacitors (as they can burst from expansion/contraction). Saying that you know the X100 has a deep sleep mode, which turns off virtually everything and you'll need the master key to get into the car. I also keep a rechargable torch in the tool kit of the car powered from the panel's USB socket - I've always seem to need the extra light at night for some reason - last time was because my wife dropped her phone under the seat.

 

Indeed, its not only unnecessary but its detrimental. The rubber suspension bushings are installed specifically so that they are neutral, no stress, at normal ride height. When the suspension is fully extended, the rubber bushings are under extreme tension. Since we're talking an x100, those bushings are probably 15 to 24 years old, pretty well worn and a bit dry-rotted by now so you don't want to stress them like that. I learned the hard way. We've discussed methods to prevent tires from flat-spotting in other threads but that's not the topic here.

You might not have emissions inspections but the car isn't going to be operating at its most efficient until it re-learns its optimum fuel and ignition mapping. Decades ago I used to have an 89 Toyota Supra that took two weeks driving to finally settle down after disconnecting the power. I dreaded having to work on anything that required disconnecting the battery and would sometimes "take my chances" just to avoid it. Today I have five cars "plugged in" at all times. Just be sure to buy a high-quality "smart" charger like a CTEK that shuts itself off completely if it detects anomalies in the float charging system so that it doesn't overcharge the battery. The electronics in some of the cheaper units don't have any redundancy and can fail in the "full on" position rather than shutting down. Learned that the hard way too.

 

The battery tender is connected directly to the battery (in the trunk/boot) right? Not to the charge points in the engine compartment?
I'll likely only drive my XK once or twice a week. I worked from home most days, pre-pandemic, and all the time now, for the past year. I just look for excuses to go for a drive. I have many: It's nice out, I need a break from these screens, I gotta run an errand, it's a day that ends in "y." You get the idea. However, once or twice a week at best and less with the heavy rain (and SNOW last week!!!) I figured I needed a battery tender.

 

I leave my battery connected with a battery tender hooked up to it for the 6 months that I have it parked in a non heated shed for winter. Temperatures can get to -30C with 1.5 - 2 meters of snow build up here and it starts up first crank every spring with no reprogramming of the windows, radio etc and none of the annoying fault warnings that come with a low battery. After a few minutes of rough idle it settles down to it's usual purr and drives like when I parked it. Along with Davids great ideas I give it an oil change and an Italian tune up before I park it adding fuel stabilizer and a full tank of gas on the way home. Adding a few Bounce dryer sheets in and around the car seems to keep the rodents out.

 

tEd

i found if you lock the car most of the electronic junk shuts down and doesn’t drain the battery. Then once every two to three weeks or so I start it up and drive it around the block a couple of times if weather permits.

 

That's be a problem if you leave the key(s) inside the trunk, in the rear right corner there is a small key hole to open it manually ;-)

 

For what it is worth (I live in the UK too) my battery used to die every couple of weeks no matter what I did regarding locking and alarm, etc. Over the past year I have been slowly removing all the rust from the front end of the car and completely repainting so have had the radiators out, unable to start the engine. The battery was disconnected for nearly a year but yesterday I reconnected it and unbelievable as it is the engine fired up instantly.

obviously windows and radio need resetting but this is the same if the battery dies. Haven't noticed any issue with TCM but I have a 4.2l with zf 6 speed so may be different with the older model.

 

For what it is worth..................
When the Jaguars are sent to North America, they have installed what is referred to as a BATTERY ISOLATION DEVICE or TRANSIT ISOLATION DEVICE.

We were required to remove the device and return it to the parts dept for 'recycling'.

The batteries were required to be DISCONNECTED during the time the car spent on the transport ship and waiting in yards at ports.
The BRAND NEW cars suffered NO DAMAGE due to the battery being disconnected. I promise that disconnecting the battery will not damage your car.

bob

 

"VERY INTERESTING"

Was going to post picture of Artie Johnson but it might seem
Inappropriate today.

 

I would agree with that.

Thanks

 

Why would it be Inappropriate Today?
I am of British and German heritage.(with some Irish & Scottish thrown in)
I am not triggered or offended by jokes, memes or other forms of humor aimed at races or ethnic groups.

Remember that in order for a joke to be funny, there has to be an element of truth or it 'falls-flat'

 

After reading this thread I was interested in finding out my cars quiescent current. (2004 XKR 4.2)
I connected a data logging multimeter to measure/monitor the battery drain after locking.

The 1st graph is of the initial 2 hours and shows that it drops in stages until reaching 30mA after approx 1 hour.



The 2nd graph shows the full 72 hours. The current drops slightly again after approx 6 hours to an average 26mA for the rest of the test.