Almost Dead Battery in 10 days

[marysc6]

I didn't drive my new M45 for 10 days. When I went to start it the engine barely cranked over, like the battery was almost dead.

I have had other cars which rapidly drain the battery when not driven. In one case it was a program error which was fixed with a computer reflash. This was a C6 Corvette.

Is it common for the M45 to drain the battery this fast? Thanks

[Q45tech]

Yes common due to large numbers of system memories/ alarms. But the question is was the battery fully charged prior to the 10 days?Simple test is does battery read with an accurate VOM 12.7 volts with engine and loads off?12.7 = 100%12.2 = 60%12.06 = 50%

The usually battery life is ~ <3 years.

[szh]

Dennis's comments not withstanding, I find it extremely unusual for the battery to drain the point where it does not crank well after just 10 days. Particularly on a new car and new battery (my assumptions here ... please correct me on that - how old is the car and battery?).

Assuming that there is nothing wrong with some car component that is draining the battery (have the dealer check it out for current draw when turned off!), then it is most likely that some light was left on during that time, or the door was ajar, or something like that anyway.

Something similar happened to me a while back ... I was on a business trip and left my car at the airport parking lot for about 4 days. When I came back, the battery was stone cold dead and needed a jump start from the parking lot folks (free jumps at San Jose Airport Parking ... one saving grace for the high cost of parking there).

After I got the jump, I discovered that my son had left both the rear reading lamps on when I dropped him to school that morning, before I went to the airport. Since I parked outside (in broad daylight), I did not catch the lights being left on - I probably should have, in retrospect, but I was rushing to catch my flight!

Sure enough, this was enough to drain the battery ...

Z

[Q45tech]

Always a good idea to measure the current draw of each individual system when cruising along. You will see the sum leaves little if any reserve to recharge a dead battery.

Fuel pump [7], ignition [8], injectors [6], fan [10], radio [10].............A nearly dead battery may require 5-6 hours at 60 mph to recharge to 80% if ac fan is on low and headlights are off.

What happens is a typical half charged battery unless you are careful to modify driving style to keep it properly fully charged.

That 30 minute cummute may leave it worse off than when you started.

[szh]

Good info. Thanks, Dennis!

Z

[FB3]

I had an '06 C6 Corvette, but never had a problem with a dead battery that was common with the '05 manual transmission cars.

The first thing that I did with my new M35 when I got it home was hook it up to my Battery Tender. It took almost a full day to get the battery up to full charge.

New cars are started, moved around the lot, into service, etc. and the battery never does anything but discharge.

Anyway, try to trickle charge it and see how long it lasts. If it still runs down in a week or so, I would have the electrical system checked.

[szh]

Anyway, try to trickle charge it and see how long it lasts. If it still runs down in a week or so, I would have the electrical system checked.

Good advice.

Z

[Pashdut]

Always a good idea to measure the current draw of each individual system when cruising along. You will see the sum leaves little if any reserve to recharge a dead battery.

Fuel pump [7], ignition [8], injectors [6], fan [10], radio [10].............A nearly dead battery may require 5-6 hours at 60 mph to recharge to 80% if ac fan is on low and headlights are off.

What happens is a typical half charged battery unless you are careful to modify driving style to keep it properly fully charged.

That 30 minute cummute may leave it worse off than when you started.

One thing I love about my 06' M35 is that if I leave the map lights on by accident, the car will automatically turn them off for me (when engine is off) because the system knows I did it accidentally. So then it would be impossible for battery to drain with map lights on.

[JerrySC]

Did you happen to leave your seat heat/cool on?

[mazz]

seat heating cooling turn off with the ignition on my 06 m35mazz