This might be a stupid question, but here it goes anyways... How long is it safe to leave the car on without the engine running just on the battery without having it die out?

Thanks!

 

depends on your batt size, how much it's charged, and the temp outside.

So impossible for us to say without the batt specs.

 

Well I guess the battery that comes with a stock RX-8, unless they have different ones?

 

If you are not running anything special while the engine is shut off, there still will be a very small current drain--sometimes referred to a dark current--which should be in the neighborhood of 20-50 milliamps (mA). Things like the clock, radio button settings, and other housekeeping systems are responsible for this drain. A healthy battery should last for several weeks before dying in this case.

If you are running an aftermarket audio system with a big amp and speakers, the draw will be significantly greater than that and just how long it would be before the battery dies will depend on the specific current draw and the duration of the draw. If the draw is say 10 amps, a fully charged, 50 amp-hour battery would theoretically last for 5 hours before dying.

 

Dominator, I will relieve your sense of stupidity with an even stupider question: can somebody tell me where the battery is? I haven't had a need to find it in my first 3 months, but if I ever need a jump, I won't be able to tell anyone where to hook the cables.

 

^under the hood









But seriously, take the engine cover off and its under the 2nd cover from the left.

 

Yeah, I think it says BATTERY on the cover. I think I'll pass on a flight in your Learjet.

 

^

 

What if i just have my radio on and everything is off, stock audio system and all. Last time I waited in the car for 3 hours with the engine running and it ate up way to much gas, so thats why I'm wondering if i can just shut the engine off and run the radio off the battery?

 

Running the OEM radio for 3 hours with the engine off should not be a problem for a healthy battery. Key words are: healthy battery. By that I mean a battery that's in good electrical condition (no internal shorts, no corroded posts, good grounds, not worn out, etc.) and is fully charged.

 

I wouldn't run it more than an hour with the stereo on. Even then you are pushing it. It drains the battery and the starter needs alot of power to crank the engine. You definitely run the risk of not being able to start the car with anything more than an hour. This is assuming you have a brand new battery if not, then I wouldn't go past 30 minutes without starting the car and charging the battery. I also wouldn't suggest doing this very often as the stock batteries aren't meant for it.

Other options are:

1. Keep the car running and don't worry about the gas.
2. Stop sitting at idle for 3 hours, just shut the car off completely and go inside
3. Get a deep cycle battery that is meant for this sort of thing. I would go with an Optima Yellow Top Group 35.

 

Does the RX-8 have a 10 minute limit on the retained accessory power, of course, that is if you take the key out.

From my experience, I can usually tell when the battery is starting to die and that is usually when I turn the car on. How long that takes to happen depends, I wouldn't run off the battery for three hours though.

 

Don't worry. I'm not offering.

 

If you know before hand, you're gonna be spending that much time in your car listening to the radio, bring your Ipod.

 

haha, well done.

 

Someone in another recent thread reported not being able to start his car after 45min with the radio on, engine off.

Seriously if you're going to be around the car for 3 hours listening to the radio, I'm guessing you're either washing/waxing/cleaning it or changing parts / toolin' around, so just get a portable radio/boombox of some sort and plug it in nearby. Might want to get a cooler and some beers while you're at it