Cold, dead batteries: Does fate hate me, or does science?

Cold: Cold and snowy.
Cold: Cold and snowy.Courtesy jpmatth
JK! It’s science, of course.

Usually science loves us, and we love science, but when the temperature drops (or, here in Minnesota, when the temperature drops and drops and drops) science starts to hate us just a little bit.

How do I know this? Because, like so many other lost and lonely souls, when I went out to start my car this morning… it did nothing. And I think I heard it mutter an awful, awful word at me from one of the dash vents.

So what gives, science? Yes, I understand that I would die if I were left out all night in -30 degree weather, but my car is a robot, and robots can’t even comprehend the weaknesses of humans, much less experience them. Why did my car die?

The car died, of course, because the battery died, and the engine couldn’t be started.

Why do batteries die in the cold?

It boils down to my old acquaintance, Chemistry. (I’m Science now. Pretend I’m Science.) Batteries can work in the first place thanks to a chemical reaction taking place between the positive and negative terminals. In a car battery, the terminals (to which you clamp jumper cables) are made of lead and lead dioxide (which is a lead atom with two oxygen atoms). Between the terminals is sulfuric acid (which is a sulfur atom with four oxygen atoms and two hydrogen atoms). The lead terminal wants to react with the sulfuric acid, and so it does—it kicks the hydrogen atoms off the sulfuric acid, and combines with what’s left to create lead sulfate (which is a lead atom a sulfur atom, and those four oxygen atoms). When the hydrogen is kicked out of the sulfuric acid, an electron is also released. On the lead dioxide side, hydrogen is getting kicked off the acid, and oxygen is getting kicked off the lead dioxide. Lead sulfate is formed again, and, with the help of the free electron from the lead terminal side, that spare oxygen and hydrogen combines to form water (which we all know is two hydrogen atoms and one oxygen atom).

All of this is only going to happen, however, if there’s a wire connecting the lead dioxide and lead plates outside the battery, so electrons can flow from the negative (lead dioxide) terminal to the positive (lead) terminal. If there’s something in the middle of that wire, like the starter for an engine, those electrons can do some work.

Unfortunately, this chemical reaction also depends on temperature. The colder it is, the less willing all these molecules will be to mess around with each other, and fewer electrons will be tossed around. If it’s really cold, there may not be enough of a reaction to start your car. Also, because the reaction produces water, there’s a chance that the water could freeze if it gets cold enough, cracking the battery case altogether. Then you’re really up Brown Creek.

If you’re battery is just low, and the cold has made it weaker, you might try jump-starting it (remember, positive terminal to positive terminal, negative terminal on the live car to a metal spot on the dead car). With the help of a fresh battery, your weak battery could build up enough charge to start your engine, which would warm the battery and start to recharge it. If your battery is frozen, however, don’t try to jump it—it could explode. Now, an explosion would be kind of awesome, but flying battery acid is scary, and it doesn’t matter if it’s science’s fault or not if your face gets burned off.

So that’s why our cars didn’t start this morning. Feel better? No? Me neither.

Your Comments, Thoughts, Questions, Ideas

Liza's picture
Liza says:

But, JGordon, how do you know if your battery is frozen? :)

posted on Fri, 01/16/2009 - 6:07pm
JGordon's picture
JGordon says:

I was hoping no one would ask that, actually.

I'm not sure. You jump start it, and then see if your face has burned off or not?

Or you could check to see if the casing is cracked.

Maybe when the world is frighteningly cold, you assume the battery is frozen. That's what a manual would say (but, then, we all know who uses manuals: losers)

posted on Fri, 01/16/2009 - 6:41pm
Anonymous's picture
Anonymous says:

If its frozen is it garbage or should I just bring it indoors, wait for it to reheat and then re-charge it?

posted on Sun, 01/18/2009 - 11:03am
JGordon's picture
JGordon says:

If it froze and cracked, then, yeah, it's no good to you any more. But if it just got cold to the point where it was no longer able to produce enough current to start your car, you might try letting it warm up.

When I tried to start my car on Friday morning it was about -15 out. and my car had no interest at all in starting. When I got home from work, the temperature had risen to about 3 above, and the car started on the second try, with no jumping.

However, I think that a battery that freezes or dies very easily in the cold is probably on its way out anyhow—when enough water has built up in it for it to freeze, that means that chemical reaction I described has been going on for a long time, and it's not a very young battery any more.

posted on Mon, 01/19/2009 - 11:09am
ARTiFactor's picture
ARTiFactor says:

Back in the good old days when temps often went to 30 below (before you were born, John) I would bring my car battery indoors overnight so I could be sure to get to work in the morning (teaching 9th graders about how batteries worked, etc.).

posted on Mon, 01/19/2009 - 12:16pm
ARTiFactor's picture
ARTiFactor says:

The best I could do to verify that "temps often went to 30 below" is this link to Brainerd temperature records.
Lows of -30°F or Lower in Brainerd, Minnesota
check out 1978-79
16 days in January had lows of 30 below (or more)

posted on Mon, 01/19/2009 - 2:29pm
ARTiFactor's picture
ARTiFactor says:

The winter of 1977-78 was brutal.
In MPLS/S Paul, winter of 1977/78, the temperature did not get above freezing for 66 straight days.

LONGEST PERIOD.................. 66 DAYS 16 HRS
8 PM DEC 18 1977 THROUGH 11 AM FEB 23 1978

posted on Mon, 01/19/2009 - 2:43pm
shaunalynn10's picture

my battery died twice this winter it sucks

posted on Thu, 01/22/2009 - 6:49pm
plee057's picture
plee057 says:

good thing I"m not getting a car for a while

posted on Thu, 01/22/2009 - 6:53pm
spark plugs's picture

i really hate snow.. all my car parts including spark plugs, engine, batteries and even wheels are really got affected..

posted on Tue, 10/27/2009 - 11:47am
CaveMaster's picture
CaveMaster says:

Most batteries too will expand (get odd shaped and rounded) on it's walls if it's frozen. Sometimes cracks dont even occur, but rather 'expansion' of the battery walls that you will definitely notice (if it doesn't crack first)


posted on Wed, 12/16/2009 - 12:26pm
Sean's picture
Sean says:

As a precaution measure you can carry in your car a portable jump starter. This should be really mandatory during harsh winter and when you drive in isolated areas, so you're not running the risks of being stuck until spring time:-)

posted on Thu, 03/29/2012 - 5:09am
neeraj's picture
neeraj says:

cold weather are maked from mix hot and rain weather mix weather are mostorised temprature cold weather time sunlight is very slows and air is up and down so this time air is makeing cold temprathure cold temprathure time battory shell not obgerb into the water so the battory sheel is jamed sao battory not passed the current and car are not stareted

posted on Sun, 07/14/2013 - 2:40am

Post new comment

The content of this field is kept private and will not be shown publicly.
  • Allowed HTML tags: <a> <h3> <h4> <em> <i> <strong> <b> <span> <ul> <ol> <li> <blockquote> <object> <embed> <param> <sub> <sup>
  • Lines and paragraphs break automatically.
  • You may embed videos from the following providers vimeo, youtube. Just add the video URL to your textarea in the place where you would like the video to appear, i.e. http://www.youtube.com/watch?v=pw0jmvdh.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Images can be added to this post.

More information about formatting options