Interesting Paradox: Heat Zaps Your Battery, Just like Cold

Here's an interesting paradox - one that is probably a lot more familiar to folks in the Northwest this summer than elsewhere or even Australia where the weather has been abysmally hot for some years - the hotter it gets, the worse your car's battery works.

It almost seems like an oxymoron to say it, but it is true because batteries are meant to work most efficiently within a certain range of temperature -- that range is usually right between 40 degrees Fahrenheit or just above 0 Celsius and about 75 degrees F or about 27 degrees C.

Even the modern NiMH (Nickel/Metal Hydride and) and others operate most efficiently within this same narrow temperature band. Surely, there are technologies that do stretch this rather optimal range, but they are still highly experimental or expensive (fuel cells come to mind as do other forms of batteries like lithium-ion) and they have their limitations, too.

So, we are left with the good old standards that occupy the engine bays of many cars today, the lead/acid or, in some hybrids, the NiMH or variant. This means that when the weather turns super warm, these batteries, especially if they are on the edge of oblivion.

What is oblivion for a battery? It's that sickening sound when you crank your vehicle over and it seems to start up find and then suddenly the cranking gets harder and harder and the noise from under the hood becomes less and less until finally all you hear, if you are lucky is click, click.

So, what do you do? There are several solutions to this problem. If you are the lazy type and have the money to for AAA or roadside assistance, you pickup your cellphone and call their assistance number and wait. If the weather is hot enough, don't be surprised if the wait is long, but they will get to you and they will get you started or at least get you to a service area where you can fix the problem (on some hybrids this might be the only way to do things because they have 144-volt racks of batteries and if one the cells goes or a bank goes bad then you might cook the engine if you tried a conventional jump, that is if the roadside assistance person has the right equipment in the first place).

If you are one of the not so fortunate that does not have AAA or roadside assistance, then you have some options, especially if your vehicle is equipped with a standard battery. If you were a nice person and Santa left you a jumper box for Christmas, then all you have to do is make sure it has a full charge, pull it out of the trunk, match the "+" and "-" arrows and attach the red wire to the "+" and the black to the "-" and then wait a couple of minutes while the battery takes a bit of a charge and it should turn right over.

If you were not as lucky at Christmas and have to do it the old fashioned way, then find a good friend with a good set of jumpers and get your cars as close together as possible. Hopefully the jumper will stretch from your car to his.

Take care in wiring things up. On your side, be sure that the red or bright jumper cable (there are yellow and black cables as well as other colors, with black universally as ground), is on the positive terminal of your battery or the battery post labeled "+" and be sure the black wire is secured to the "-" post.

On the other side, be sure that the red wire is hooked the positive or "+" side of the battery and then find a good ground point for the black cable, say a solid metal engine stay or sheet metal screw and attach the black wire to that point.

One thing to do in a situation like this is let the vehicle with the good battery put a charge into the vehicle with the failing battery so that you will see if the battery is totally hosed or it's just something silly like a door left ajar and a light left on for too many hours. In many cases, this is exactly what happens.

With today's battery technology, it isn't unheard of for a standard battery to run fine for four years or so, but when it decides to go, it goes. The only way you know that it's going to happen is if your lights darken when you take your foot off the accelerator at night when you are idling at a light or if the turn signal speeds up and slows down as you turn a corner. Those are two telltales that something is wrong. The biggest, though, is the vehicle that just won't start and for which you need a jump.

Be sure to handle the jumpers correctly because it is very easy to crosswire everything red/black-black/red, instead of red/red-black/black. Cross wiring is catastrophic to your electrical system, as it will burn everything out.

So, whether it's high temperatures or low temperatures, batteries have their range and their longevity. As long as you stay within the right range or keep your battery relatively fresh, you'll be all right.

One last note, it's a good idea, despite whatever the manufacturers may say to swap out your battery every 36 months, whether it needs it or not. It just makes sense not to tempt fate.