I don’t understand what is different that prevents cars from starting right up in cold weather. Fuel is present, air is there..spark plugs are …sparking ..and as long as you have a strong battery the starter is turning the engine…why the struggle?
In: Technology
The oil in the engine gets thicker and harder to move when it’s colder, it is harder to turn everything in the motor over to start it, so it turns slower.
They shouldn’t have a hard time with a strong batterie. If it is older or just not fully charged for some reasons there can be problems tho, because the capacity decreases with cold temperature.
Batteries are powered by chemical reactions that make an electric current as a product. Most chemical reactions occur much slower in cold temperatures. Slower reaction = less electricity generated per second. Less electricity per second means your car can’t make enough sparks to ignite the fuel in your engine, which means it can’t start.
If you have a strong battery, these effects are small, unless you’re in like, *really, really* cold weather.
**Edit:** Another user pointed out that sparkplugs don’t actually carry the current to the engine to make it start. That’s done by a separate motor carrying an inrush current. It’s still an issue with current, just not with sparkplugs
**Edit 2:** Those claiming that engines won’t start at low temps because of oil being more viscous or that moving solids are packed closer together and introduce friction as a result aren’t *completely* wrong, but it’s not the primary reason for this occurrence. The density of a liquid or solid (such as motor oil or the metals used in your engine) does change with temperature, but the scale at which this occurs is not enough to prevent your engine from starting (at least for the majority of cars on the road). It is enough, however, to increase the amount of work required by your engine to do its job, which would increase the current needed to start your engine. You’ll also have lower gas mileage when your engine is cold vs warm for the same reason.
Lot of people are forgetting that when a reciprocating engine is cold, the tolerances between the moving parts become tighter, meaning there is more friction.
They dont have a hard time, only a diesel generally would.
Modern cars with fuel injection should never have a hard time unless the Cold Cranking Amps of the battery are so low as to cause a problem with turning the starter. It would have to be extremely cold for this to occur.
Diesels are another story entirely since they use glow plugs and rely on compression of gas to create the explosion rather than a spark plug initiating it. But modern diesels are pretty damn good with cold starts these days.
In general its probably going to be the battery more than anything else if a car is having trouble starting in cold weather.
It is not the liquid gasoline that burns, it is gasoline vapor. Fuel injection helps to vaporize gasoline better than a carburetor, but it’s still not good if the temperatures are extra low.
If a four-stroke engine is spinning at 600 rpm to idle, then it needs a spark to ignite gasoline vapor 300 times a minute. That means the spark has to try to ignite a new sample of gasoline and air about 50 times a second.
This is why you can smell gasoline in the exhaust on a cold engine. Half of it vaporized and burned, and the other half was pushed out of the cylinder before it was able to vaporise.
Also, use synthetic oil when its extra cold, to reduce friction.
Have you ever tried to move your hand after not wearing gloves in freezing weather? You might notice your hands moving slowly. In other words, your hands have a hard time moving. Your car is like that.
I would add that the majority of the power being used when starting your car is used just to get the engine moving. In ancient cars this was done with a hand crank on the front of the car. Eventually this was replaced by the electric starters we use now that uses electricity that spins a gear that engages the flywheel to get the engine to start turning.
Getting that flywheel turning takes a lot of force (energy). Think of starting your lawnmower and how much force that takes. That’s just one small, low compression piston. Now imagine the force (energy) that it would take to start much larger, higher compression engines especially ones that are turbocharged. That’s a lot of force or energy that is required to be converted from electricity to mechanical force.
Batteries work by using chemical reactions to make electricity. Chemical reactions happen when molecules bump into each other. When the molecules are warm, they’re bumping into each other more often. This allows the chemical reactions to happen faster, which allows for more electricity to come out of the battery.
The engine of a car is started with a starter motor that’s powered by electricity. If the car is cold, the battery produces less electricity, and the starter motor can’t turn over as easily. This makes the engine harder to start.
> I don’t understand what is different
The battery has less power, AND is fighting more resistance.
1. Cold makes chemical reactions go slower. That includes batteries – which have less power as it gets colder.
2. The engine has a bunch of parts sliding through fitted openings, with a lubricant. As it gets colder, the engine block shrinks and all the fittings get tighter. At the same time cold also makes oil (the lubricant) thicker and harder to move.
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