I went on a 3+ week vacation leaving my Z in the garage. I didn't think about it, but something ran the battery down, when I tried to start it, it just clicked. I threw on the charger for a minute and it started fine. However, my Compustar won't work, and when I get out of the car, and shut the door, both windows roll down about half way. Also, the red factory alarm (which is disconnected, I believe) LED is on while driving.

Any idea?

Thanks

 

LOL. next time disconnect the battery when going for a long break.

i really dont know what to say. its just funny.

 

Turns out that the Alarm brain died and that was messing with the windows .

 

Hey Billp,

I have the same issue with a dead battery after long periods of not using the car, around 3 weeks. I am currious to know if your car is completly stock or if you have done some aftermarket electrical things ie: stereo, ecu, etc.?

I tested for a parasitic drain and found my car is drawing 100mA with the car off after the timeout period. All modern vehicles draw some small current to maintain the memory on the radio, ecu, etc. I am wondering if this is a normal amount of draw for our vehicles.

What caught my eye on your post is that you mentioned 3 weeks. That is about the same length of time it takes for my battery to go dead and if we do the math it seems to verify that length of time.:

100mA or .1 amp/hour X 24 hours = 2.4 amp draw per 24 hours or 1 day
Our OEM battery is rated at 52ah so:
52/2.4 = 21.66 days to discharge or 3 weeks.

With your experience of 3+ weeks of non use, my experience of around the same amount of time, and the math, maybe this is normal for our cars?

With a little search and talking to several mechanic friends it seems that other cars draw less. For example Hondas have a spec that says 30mA or less. Certain GM vehicles 35mA or less. Mechanics have said 50mA or less. Any of these scenarios would allow the car to sit for 2 months before a dead battery. I tested the parasitic drain on my 06 Landrover and that was only 10.6mA! With the 75ah battery in that truck it could sit close to a year before a dead battery!

It seems like a short period of time for our cars to go dead as compared to other cars but with the multiple computers, can system, etc. maybe it is normal. I guess I am looking for more info on this too.

What are others experiencing? CHIME IN!

Jeff

 

Thanks Jeff, I agree that the 3 weeks were normal, I thought that if I disconnected the battery, I would have to reprogram the car. It was the Compstar alarm, they replaced the brain and all works well now. In the future, if I'm going to be gone that long, I'll take off the cable.

 

You consider buying a Battery Tender. They do an excellent job keeping the battery properly charged.

Les