Batteries don't do so hot when it's cold.

If you live in a cooler climate, you may have noticed this in the form of your car refusing to start on a chilly morning,

or your battery level plummeting on your phone as you stand on the train platform in the freezing cold.

But it's not the batteries' fault exactly.

It's not that technology works worse in the cold.

It's chemistry.

And that's a much harder problem to fix.

Batteries aren't just big buckets of negatively charged electrons,

even though that's what moves through the wire when you plug a battery into something.

The electrons start as part of neutral atoms or molecules, and they're released by a chemical reaction inside the battery.

As a result of the reaction, the electrons move through a wire and meet up with positively charged molecules on the other side of the battery.

That movement creates a current that powers your stuff.

The exact chemistry depends on the type of battery, but that's the general idea for all of them.

And it's also where temperature comes in.

Temperature is a measure of heat.

And at a molecular level, heat is movement.

It's particles jiggling around.

Higher temperatures mean more molecular movement and more molecules bumping into each other,

which makes chemical reactions more likely.

So, in general, when the temperature drops, chemical reactions slow down.

But how much depends on what's reacting.

Which helps explain why you might notice some batteries suffering more than others in winter.

Not all batteries are made from the same stuff.

Traditional alkaline batteries, for instance, like many non-rechargeable AAs, AAAs, and the like, contain a solution of water and potassium hydroxide.

That watery solution can freeze at really low temperatures,

but it starts losing its chemical punch well before it actually turns to ice.

So don't try to use your TV remote outdoors in a blizzard.

That's our advice for you.

Then there are lithium-ion batteries like the one in your phone.

They tend to beat alkalines in cold weather, but even they have their limits,

something that's been holding back electric cars in areas that get really cold.

A phone battery's cold-weather performance actually tricks the phone into thinking it's dead.

The difference between a charged, cold battery and a dead battery is that the charged battery

still has the capacity to produce enough electrons to theoretically power your phone.

But because the temperature slows down those reactions, the electrons are released too gradually to do any good.

Your phone doesn't have a thermometer, meaning it doesn't know how cold it is.

So it just assumes there's nothing left in the battery to react -- which is what happens when the battery's dead.

So the phone tells you the battery is low, when really it's just cold.

Warm the battery up, so that more reactions can happen again, and the phone will realize it still has more juice.

One other very common battery is the lead-acid battery, widely used in cars.

Cold slows that reaction, too -- but it also makes oil and other components of the engine harder to move.

Sp that's double trouble for you, making some cars particularly hard to start on cold mornings.

So be nice to your batteries this winter.

If your phone dies on you, just hold it against your body like a little baby duck.

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