Will my car start when I get back?

[Colonel Cadillac]

I left my car in storage in Houston on the 23rd-ish of May. I did not disconnect the battery, because I would have to reset a whole load of electronics if I did and that would be a huge pain in the ass. I figured it was worth the gamble to keep it connected and pray that it kept some charge. I get back there on the 29th or 30th, what do you think...will it start?

[Onslaught]

I've left the miata parked for much longer then that and it started. In the winter too.

[CJ]

Something may or may not happen. 

[Northlands]

Probably. If not, get a boost.

[Payman]

Unless the battery is really old, it should start the car just fine.

[AutobahnSHO]

I parked the Subie Jan-July 2011, in the garage though. Started up with half a revolution of the starter. (Used stabilizer in the gas too.)  Then it sat Aug-Jan and again started fine.

[hotrodalex]

If it was an older car or one with less electronics, maybe. But Audis and BMWs have lots of stuff to drain the battery. It may still start, but I still vote no.

[MX793]

I parked my Mustang in November of last year, left the battery hooked up, and it fired back up in March when I brought it out for the season.  Unless there's something wrong with the car, battery should be fine.

On the flip side, I parked my Mazda on ramps in my garage sometime in June and when I went to drive it to the dealership for my annual inspection (and to address a few other issues I couldn't fix) two weeks ago, the battery was completely dead.  Not sure if I accidentally left a dome light on or what.  It was so dead that even when hooked up to my (running) Mustang with jumpers, it wouldn't immediately turn over.  I had to wait about 10-15 minutes for the Mustang to charge the Mazda's battery before it had enough juice to turn over and fire.

[Raza]

May until now?  Yeah.

[Speed_Racer]

Trickle charge it when you get back?

[TurboDan]

I take my boat out of the water in late November and put it back in April, and it always starts just fine on the first turn of the key. No trickle charger.

[TBR]

But you probably have some kind of master switch that effectively disconnects the battery, right? Even if you don't, IIRC your boat is fairly simple thus it isn't going to have much connected anyway.

[J86]

But you probably have some kind of master switch that effectively disconnects the battery, right? Even if you don't, IIRC your boat is fairly simple thus it isn't going to have much connected anyway.

[Raza]

I had my Boxster parked for months without anyone ever touching it and it worked fine.

[hotrodalex]

Our BMW wasn't driven much last winter since my dad was out of town every week and it just sat at the airport. A couple weeks ended up killing the battery (it's fine now, just needed to be jumped a couple times).

[Raza]

I wonder if the age of the battery should be a factor.

[shp4man]

The higher the CCA (cold cranking amps), the longer batteries last with parasitic drain that's caused by keep alive circuits in electronic crap. Temperature and age of the battery are also factors.
Auto Shop 101 is dismissed.

[Colonel Cadillac]

Negative. Needed a jump. I've needed 2 now.

[AutobahnSHO]

How long did you run it after the first? Battery might be toast.

[hotrodalex]

Looks like I win this thread.