Warming up the engine to recharge battery

[CosmicWizard]

My car has been sitting undriven for more than 24 hrs in Below Zero wind chills. I'm concerned about the battery ( 4 yrs old, $160 ) in my 2012 Honda FIT. I've read conflicting reports about the effeciveness/dangers of starting it and idling the engine. Would like to hear back from someone who has actual experience with this issue. What are your recommendation? If YES, how long to let it idle.

[reed303]

See https://www.interstatebatteries.com/support/faqs
where it says:
"The amperage or current output of an alternator is more than adequate to power the vehicle and charge the battery as long as the vehicle is driving down the road. At idle, the current is lower and may be less than adequate."

Excess idling when cold is also bad for the engine. Raw gas can get in the oil if engine does not get fully warmed up.

[CosmicWizard]

Originally Posted by reed303

See https://www.interstatebatteries.com/support/faqs
where it says:
"The amperage or current output of an alternator is more than adequate to power the vehicle and charge the battery as long as the vehicle is driving down the road. At idle, the current is lower and may be less than adequate."

Excess idling when cold is also bad for the engine. Raw gas can get in the oil if engine does not get fully warmed up.

Thank You! That makes sense.

[kwong7]

Originally Posted by reed303

See https://www.interstatebatteries.com/support/faqs
where it says:
"The amperage or current output of an alternator is more than adequate to power the vehicle and charge the battery as long as the vehicle is driving down the road. At idle, the current is lower and may be less than adequate."

Excess idling when cold is also bad for the engine. Raw gas can get in the oil if engine does not get fully warmed up.

And water can sludge the oil from excessive amounts of cold air not running through a warm engine cycle. As for the OP, it's best to run the car and drive somewhere to get the drive belt to turn the alternator at a faster RPM...idling would just be around 600-1,500rpm. If your car is garaged parked, you can hook up a battery tender every 3rd day or so to make sure the battery voltage doesn't drop too far. A digital battery tender can be bought on Amazon for like $10 these days.

[NORTY FLATZ]

Originally Posted by CosmicWizard

My car has been sitting undriven for more than 24 hrs in Below Zero wind chills. I'm concerned about the battery ( 4 yrs old, $160 ) in my 2012 Honda FIT. I've read conflicting reports about the effeciveness/dangers of starting it and idling the engine. Would like to hear back from someone who has actual experience with this issue. What are your recommendation? If YES, how long to let it idle.

Since you are located in an area that gets cold, and you have a battery that's 4 years old, I'd do a little preventative maintenance by replacing the battery, BEFORE you are stranded. If my life depended on a battery, 100% of the time, I'd be replacing it every 2-3 years.

If you're car doesn't get driven much, then I'd hook up a battery tender to it, for those down times.

As other posters mentioned above, it's NOT a good idea to let an engine "idle" with the hopes of charging up the battery. Now, if you drove the car for 45 minutes, THEN you'd have it hot enough, LONG ENOUGH to boil off the water condensation that is in your oil sump. But, beware, as the engine cools down, it'll start pulling humidity from the atmosphere and depositing the water vapor back into the oil pool once again.

It's a vicious circle we live...