I didn't drive my car for months.

Jump-started it once for a minor drive, but then didn't drive it again for a few weeks.

All of this happened during cold winter.

Now I jumped it again, with the intention of driving it regularly again. I let it idle for 30 minutes, and it wouldn't start again after I turned it off. I jumped it again, drove around for 45 minutes (and I forgot to turn off the AC and radio during this ride), then parked it and turned it off (and I did not try to re-start it immediately).

My question is, when I wake up tomorrow, if the car doesn't start, is that an indicator that the battery needs replacing, or should I try to jump it again and drive it around for longer with all AC and radio off?


You can do several things prior to assuming the battery is dead, but more than likely it is.

Put the battery on a 2Amp charge overnight. Then turn the headlights on for about 10 seconds. Then test the batter with a digital multimeter (DMM). If the charge is above ~12.5vdc, it should be able to survive, at least for a while. If it is below the 12.5vdc mark, take the battery to a local auto parts store. They can put it under load and give you the approximate life of the battery or it's actual capacity. They can tell you for sure.

The problem here is, you've let the battery sit too long. A battery will lose energy over time as it sits, but then throw a the minor load of a car onto it and it will completely drain the battery. A battery likes to be charged and lives a long, healthy life if you can keep it that way. In the future, if you plan on letting your car sit, put a battery tender type charger on your car. They are relatively cheap and will keep the battery up to shape without overcharging. A "trickle charger", or even the 2A charger (most low settings on regular chargers) will overcharge the battery given enough time and will cause it to (in most cases) boil over. The battery tender won't do this, but rather will help the battery stay where it likes to be ... charged.

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