Car - Battery Life

How can you prevent your car battery from dying?  This article from the Globe and Mail has some helpful answers. Here are the key points.

How often do I need to drive my car?

Drive the car on a regular basis, every 3 - 4 days. Each time, you want to drive for at least 10 km a time, and longer in the winter.

“The best thing [to do to keep your battery charged] is to drive the car on a regular basis; every three to four days should be fine,” says Calvin Feist, instructor at NAIT in Edmonton. “It needs to be driven and not idled.”

"...Even if you’re driving every day, but only for short trips to the store, you’re shortening the life of your battery because it never fully recharges...That means driving at least 10 km at a time, and longer in the winter, because you’re using the heater, rear defroster and heated seats – they draw a lot of power, which means less power will be available to recharge the battery, Feist says."

What if I'm going to be away for a long time, like a few months?

Option #1: Disconnect the battery negative cable.

"So how do you prevent the battery from dying? If the car is going to be stored and won’t be used at all for a few months, you could disconnect the battery negative cable, says Stephen Leroux, professor at Centennial College in Toronto. That will stop the car’s electrical system from drawing power from the battery.

Option #2: Install a smart charger.

"That’s probably not realistic if you’re living in a condo and still might need to drive – in that case, Leroux recommends installing a smart charger.
Unlike a traditional charger, which can eventually overcharge a battery, a smart charger only delivers as much power as your battery needs – once the battery is fully charged, it will turn off the current.
They can stay in the vehicle all year round – you end up with a plug hanging out of the front of your vehicle, just like with a block heater.
“You plug the car in and forget about it,” Brown-Harrison says. “For the average driver, plugging it in once a week overnight is enough.”

It can stay plugged in all the time, but if you don’t have regular access to an outlet, even just a three to four hour charge once or twice a month should do the trick, says Sergio Marsili, product specialist with Canadian Tire.

“For only $30 to $40, it can save you from dealing with a car that won’t start and a lot of money in replacement batteries,” he says."

Dealing with Cold Weather

Cold weather is hard on car batteries. "At 0*F, a car's battery loses about 60% of its strength...During cold temperatures starting an engine can take up to twice as much current as needed under normal conditions." So what to do?

* "Before turning off the car, shut off all accessories—the heat, radio, interior lights—any power source that could be a drain for the battery." (link)

* Plugging your car in helps because it keeps the engine oil warm, which helps the car start up more easily, and thus increases your chances the engine will start! So on cold nights, it's a good idea to plug your car in before bed. (I guess this is a separate problem from the battery being weak. It sounds like the cold weather is hard on the battery - and thus you need to drive your car more often/longer to recharge it - and also, the oil in the car gets cold and more viscous, so it doesn't flow through the engine and lubricate things as well. Maybe taking care of the second problem can give the car just enough of an extra push to start, despite having a weaker battery in the cold weather.)

More from this link: http://www.wikihow.com/Start-a-Car-in-Freezing-Cold-Winter-Weather

Wikipedia:

A block heater warms an engine to increase the chances that the engine will start as well as warm up the vehicle faster than it normally would in extremely cold weather.

The most common type is an electric heating element in the cylinder block, connected through a power cord often routed through the vehicle's grille. The block heater may replace one of the engine's core plugs. In this fashion, the heater element is immersed in the engine's coolant, which then keeps most of the engine warm. There is no pump with this type of heater. They may also be installed in line with one of the radiator or heater hoses.

Heaters are also available for engine oil so that warm oil can quickly circulate throughout the engine during start up. The easier starting results from warmer, less viscous engine oil and less condensation of fuel on cold metal surfaces inside the engine; thus an engine block heater reduces a vehicle's emission of unburned hydrocarbons and carbon monoxide; also heat is available more quickly for the passenger compartment and glass defogging.^[1]

Other Facts

Battery life depends on several factors, including:

1. the climate (batteries die more quickly in cold weather)
2. how often you drive
3. the age of the battery

Higher-end cars typically need to be plugged in more often, because they have more gadgets and computers that use up power.

“For BMWs and some Mercedes, it’s possible for a battery to die in two weeks,” says Patrick Brown-Harrison, instructor at SAIT Polytechnic in Calgary. “We used to have to install chargers for clients who left their cars at airport parking lots for two or three weeks. That shouldn’t be as much of an issue with an Acura."

Wpg Free Press article on Battery Life (2014)

"In extreme cold, if your car didn't start one day and you leave it, it only makes it worse."

Vehicle owners are advised to start their cars every three hours if they're parked outside and not plugged in. The mechanics are basic: at temperatures of -18 C or lower, it takes 40 percent of your battery just to get your engine going. "Even if it's just for five minutes, start your car," Young advised.

- From Cleaning up winter's chaos: Snow-covered roads, stalled cars a big job, by Alexandra Paul, The Winnipeg Free Press

Why is it more difficult to start a car in the winter? - Howstuffworks

There are three reasons why cars are hard to start when it is cold.

Reason 1 - Gasoline, like any other liquid, evaporates less when it is cold. You have seen this -- if you pour water onto a hot sidewalk it will evaporate a lot faster than it will from a cooler place like a shady sidewalk. When it gets really cold, gasoline evaporates slowly so it is harder to burn it (the gasoline must be vaporized to burn). Sometimes you will see people spray ether into their engines in cold weather to help them start -- ether evaporates better than gasoline in cold weather.

Reason 2 - Oil gets a lot thicker in cold weather. You probably know that cold pancake syrup or honey from the refrigerator is a lot thicker than hot syrup or honey. Oil does the same thing. So when you try to start a cold engine, the engine has to push around the cold, gooey oil and that makes it harder for the engine to spin. In really cold places people must use synthetic motor oils because these oils stay liquid in cold temperatures.

Re­ason 3 - Batteries have problems in cold weather, too. A battery is a can full of chemicals that produce electrons (see How Batteries Work for more information). The chemical reactions inside of batteries take place more slowly when the battery is cold, so the battery produces fewer electrons. The starter motor therefore has less energy to work with when it tries to start the engine, and this causes the engine to crank slowly.

--> It sounds like "charging a car" by plugging in a block heater works because when a battery, which is basically a container with chemicals inside that undergo reactions, gets cold, the chemical reactions don't happen as fast and so the engine doesn't produce as much power. By keeping the engine and the battery warm, the chemical reactions happen quicker and the battery has more "oomph;" also the engine oil is less viscous.

http://auto.howstuffworks.com/car-driving-safety/accidents-hazardous-conditions/start-car-in-winter.htm