Hello

currently the Super V8 is in its garage, unlocked. Does anyone know if, all other things being equal, the battery will drain faster with the car locked or unlocked?

cheers people
dave

 

Ideally get a ctek-type device so it doesn't matter.

My car is a bit newer but people used to say lock it. I tried both ways and it doesn't matter for a week or two. Haven't tried longer.

Left long enough, without a ctek-type device, the car will flatten the battery and damage it so it will need replacing.

If you want to be sure, test the current draw - it's not hard just boring.

 

I'm going to guess that a ctek is the same as a Battery Tender here in the US? If so, I agree and wouldn't go more than 2 weeks without one attached. Personally I don't let mine go more than a week. My battery is around 10 yrs old I believe and before I started using a battery tender, I was going through batteries in about 4-5 yrs. So the money saved on another battery purchase alone pays for the tender (ctek) 5 fold. Plus it maintains the voltage to within a volt so power draw items never starve and keeps the electrical ghosts away.

 

Yeah, that would be ideal. I have a trickle charger but no power outlet in the garage. I'll test the current draw. But I'm v ignorant; how do I do it? Previously I'd just been disconnecting the battery, but that always results in the fobs not working for a few days and occasionally alarmingly high revs at startup

 

To answer the initial OP Q, which I got sidetracked with the ctek, no the locks will not draw anymore power locked or unlocked, they are an activation and respond to the relay, they don't have holding power. Since you don't have outlets available, is there any reason you simply couldn't go out on a Sat morning once a week and start her up for 5 minutes?

Those startup quirks you speak of is the ECU relearning as it resorted back to its default settings from no or low power from sitting, ...but excessively high revs I suspect, could be a small vacuum leak? The ctek/battery tender is what chases those ghost quirks away.

 

Thanks Highhorse

my Saturdays get full with kid stuff. My whole life gets full of kid stuff.

The thing that bugs me most about disconnecting the battery is that after reconnection the fob buttons have no effect. Then gradually the car seems to 're-learn', and I mean gradually. it takes about a week, and the lock button is always the last to be recognized. it's bizarre. I cannot think of any electronic explanation which makes sense.

Anyway, you reckon a 5 min idle once a week will do the trick?

 

Yes, it should, barring the condition of the battery. 5 minutes should be allowable time to recharge the battery and let the car run on the alternator. The only purpose of the battery, technically speaking, is to start the car primarily. Its secondary function is to maintain the ECU memory, clock, radio memory, ect, etc...while the vehicle is off. So those milliamp draw items shouldn't affect the battery as long as they are in good condition (no shorts). But when you get to periods of over a week without refreshing the power, you start to notice issues (ghosts). Your higher power drawing items will supersede the smaller ones and those will suffer if they carry a memory and even the higher power units will eventually succumb to the battery not being replenished.

Another advantage is to allow the oils to lubricate as they need to for the seals and such.

 

I did once many years ago after reading about it on this forum, test the amperage draw for locked and unlocked. After locking the doors, the current dropped quite a bit within a few seconds. I don't recall how much exactly but it was clear that there must be modules that remain active until you lock the doors. What I didn't test though was whether or not the amperage draw would have gone down on its own after some time had passed. I kind of suspect that Jaguar would have programmed it so that if you left it unlocked, but didn't get back in the car after an hour or so that it would go ahead into hibernation mode.

Just an idea, but since you don't have an electric outlet in the garage, you might research the systems used for powering gate openers and electric fences. They basically operate on 12 volt car batteries and recharge via a solar panel. I just don't know how comparable modern ones are to the CTEK or Battery Tender units.

 

It's also used to keep the alternator voltage down and to smooth it plus provide the high peak currents demanded by such as coils. The alternator can't respond fast enough for such as those. In summary, a good and working battery is essential or you get misfires as well as, commonly, weird codes.