Battery Question

[Mark86]

How long should a car be able to sit idle and still have enough juice in the battery to start? The battery was replaced 6 months ago and it died after around 2.5 weeks of being idle. At that time, the car was driven around a total of 30 minutes.The car in question is a RAV4.

 

[JP4RNR]

Depends on the size of the battery CCA (cold cranking amps). Most Alternators cannot sufficiently charge a battery at idle. You need at least 1000 RPM's before the alternator puts out any decent charge. Starting a vehicle and letting it run only at idle will overtime completely discharge the battery.

Any battery where the charge has fallen below 11 Volts will not start the vehicle

 

[Mark86]

Thanks for the reply. I meant to say the car was not started for 2.5 weeks.

 

[toto]

It depends on the amount of fancy electronics. The newer the car, the more power it draws even with everything appearing to be off. Plus there are certain features that will draw more power. For example, the automatic on/off headlight function (if you have it) will do that, and the Owners Manual warns against leaving the headlights in the "Auto" mode for more then two weeks without driving the car.

Electronically-controlled battery chargers are cheap and effective. Even the ones that sell for about $30 come with a couple of different cabling options, including a style that can be permanently attached to the terminal posts and has a quick-disconnect plug. If the RAV4 is a second car that doesn't drive a lot, you may want to check out something like that.

 

[drmorbius]

How long should a car be able to sit idle and still have enough juice in the battery to start? The battery was replaced 6 months ago and it died after around 2.5 weeks of being idle. At that time, the car was driven around a total of 30 minutes.The car in question is a RAV4.

If it sits for long periods like that you could install a battery switch and just remember to turn it off when you park it. Then the battery won't discharge. The downside is you will have to reprogram your windows and radio but at least it will start.