"Drain the battery, can't start the engine, still stuck, no more heater..."

That's basically where you would be if you didn't use the heater, and croaked due to hypothermia, right? They would tow you out, anyway.

Trying to get the last six starts out of old or defective batteries in winter is just begging for trouble, anyway. There's no point in waiting to where someone's life or well-being could be in danger.

But it would be an interesting experiment for someone who knows about that stuff. If it's really do-able, it would ease the mind of people: "It's okay, Honey! If you get stuck with the kids, just set the heater on full blast and turn the engine on for a minute or so every five or six minutes, it won't hurt anything."

Ignorance isn't bliss, it's scary in a survival situation.

Sue

Very timely discussion on the subject of car batteries and I have a few things to share.

In almost another lifetime ago it now seems, I was employed by a auto repair shop that did a lot of fleet maintenance for some very big companies at the time. One of my main responsibilities was vehicle electrial work, specifically diagnosing battery/starter and associated problems. Today, battery and vehicle techologies have changed, however the basic building blocks and theory are all the same.

To answer couple of questions that I read here. Disclaimer: This is my opinion so always do your own research and planning...


Q) Anyone have any idea if your typical alternator can mostly recharge the power lost to start the engine in just 10 minutes? I'm also concerned that with cars getting stuck for 10+ hours, a cold-weakened battery could eventually get too drained by following this hourly warming schedule.

A) Yes (and no)

Assuming a good battery and properly maintained charging system. Yes, the alternator should be able to suffuciently recover the battery in 10 minutes, Keep the engine from dead idling and press down on the gas pedal so that RPM's are around 1200-1500. This will assure that there is suffucient charge going back into the battery. Keep in mind that if during those 10 minutes you have the heater on full blast, heated seats on, listening to the radio, wipers on etc all at the same time then no, 10 minutes will not be enough.

Somewhat timely and related. I just returned from a very quick trip north about 550 miles from the Canada/US border. On the way up, the highway was closed for just shy of 2 hours due to a rockslide. The outside temps were around -8F. I ran the car for about 5-7 minutes at a time with the heater fan on medium and it warmed enough to be comfortable for me in a T-shirt, light unlined jacket and pants for about 20 minutes at a time or so. On the otherhand, my girlfriend was cold and bundled up in an extra sweater and had the wool blanket wrapped around her lower half. The starting of the car routine was repeated over the 2 hours and we could hear slight variations of it up and down the line of cars as we waited. Mind you, it appeared that some vehicles did not get turned off at all during this time and I thought more then once that someone may run out of gas and the spare 3 gallons in the trunk of our car would bring about some easy $$$ for us (our gas tank was filled about 40 miles back previous) but no car ran out...

One last point on this above question. Many fleet vehicles such as delivery trucks/cars do a lot of stop/start of the engine of short durations during the day and they do not have any trouble over the long term that would be comparable to your question.


Q) Anyone up north with an ammeter/voltmeter equipped car to determine how long it takes for the voltage regulator to click off from the high charge rate?

A) Way too many variables such as ambient temps, car alternator manufacturer, charging capacity etc,


Q) Related would be how long it takes warmed motor oil to reach a viscosity that produces undue drag on the starter motor.

A) Depends on temperature, oil viscosity, engine type: aluminium or iron, is the car in a garage or out in the driveway. Any engine will start much easier even if it has been off for 2 hours @ -20 as compared to an engine that has sat overnight at the same temperatures without a start.

How about using "Hot Hands"?
As far as I know, these release no dangerous gases.
A supply of these will keep a body warm enough for long enough to last through just about any unscheduled stoppage.
They seem to have a long shelf life.
They can be bought in bulk for about a buck a pair, sometimes less.
I would guess they could even be used to warm drinks and food.