Seriously, I'm hoping there is some sensor that remains on that may have caused my battery to die over the course of ten days sitting with the hood open in my garage. I just went out there to fire it up to test for another problem and the battery was dead as a door nail (it's a brand new battery, as of September).

This is the first time I'm noticing any slow leaks; just trying to eliminate the obvious before delving further. Thoughts? Is there a magic gremlin in the hood latch?

 

There is no under hood light and therefore no sensor that I am aware of that would drain the battery. Did you leave the key in the ignition switch over that time? That prevents the systems from going into a 'sleep' state. Without that there is enough electrical drain to have pulled the battery down.

 

I have left mine open, closed but not latched waiting for parts. Never had a dead battery. If you start the car with the bonnet open, it will state bonnet open on the dash. If the boot is open the lights turn off but will still give you a warning on the dash. So I would think with the ignition switch off there would not be a power drain. But I have read on the forum that the car being unlocked would drain the battery, I have never locked the car in the garage and it has never been an issue. But this is a jag, anything is possible. Personel I think your battery drain is not related to the bonnet being in latched. Jim

 

Thanks, now that I think of it no, the car was not locked. Will have to experiment there.

 

There was no key in the ignition. Hm.

 

I was advised by my dealer to keep the car locked, whenever it is not being driven, in order to minimize (or eliminate) battery drain.

Can you open the hood/bonnet, when the car is armed, without triggering the alarm? If not, there must be a sensor.

 

Hi.

There is a sensor, a microswitch in the RH bonnet latch. This gives you the hood open warning.
If this is connected to the security system is somewhat unclear to me.
Try to lock the car with the remote with the hood/bonnet open. If it locks you should be ok.
If not. you will have a slight battery drain as the car doesen't go fully asleep.

 

Normally car alarms go off (if enabled) with a CHANGE in a sensor like a microswitch. I've left the bonnet of my STR (and previous cars) up on occasion for at least a week and had no apparent battery drain.

 

It is connected and you will hear a long beep rather than the usual chirp when locking the car with the key fob. The doors will lock, but this is to inform you that the bonnet isn't latched. Same happens when the boot is unlatched and you lock the car.

It shouldn't be a problem though, I have left the car with the bonnet entirely off for weeks without an issue.

 

I am surprised at the dealer recommending that the car should be locked if parked long term. I would normally do this, but not in my own garage.

A dealer probably found out by having tons of them left unlocked on his lot, all going dead mysteriously. Weird, but if it works I'll try it.

 

I trickle charge my battery with the hood open (unlocked) After a few weeks the charger stops charging for a couple of days because full load reached.

The car is locked; The moment I touch the outside door handle, charching light lights up immediately.

And all other explanations I have experienced (like leaving the door open, key in the lock, etc)

 

When you remove the key from the ignition check that the cover on the barrel closes - I've read somewhere that if it is stuck open the system does not go into sleep mode and will drain the battery - it can be freed off with WD40 or the like.

 

With the car un locked and no key in the ignition the 5 main modules in the car are in "stand by" and pulling power from the battery. With the car double locked and the alarm "enabled," the car is essentially asleep apart from the security module.

 

Wow!!! I'm sure glad I read this as I keep my car unlocked almost all the time, probably about 10 hours a day I wonder what kind of damage I've been doing to my poor battery?

 

Keeping it busy for no reason !

 

Make it a habit to always lock your vehicle when it is parked, even if security is never an issue for you. Your battery will thank you and last much longer....

 

Just in case anyone would like the official figures.

 

There you have it in black & white.....the additional advantage to locking the car is that it makes it a bit more difficult for somebody to nick it!!

 

Thanks all for this info - will be leaving the car locked from now on, even in my own garage!

 

This has been an excellent thread. So much good information from very experienced guys...kudos all.