Barrow, Alaska, generally is recognized as the coldest spot in the United States. Its average temperature is a balmy 11.7 degrees Fahrenheit and has a recorded best low temperature of -56 degrees Fahrenheit. On the other side of the coin, the world record for high temperature is 134 degrees Fahrenheit, and a few cities in California were close to breaking that mark during the heat waves experienced this past summer. And while this article is going to talk about preparing for the low side of the scale, many of the tips shared apply equally to hot or cold climates.
Let’s Start With The Battery
A battery provides electromotive potential via a chemical reaction, and that reaction slows as temperature drops and increases as temperatures rise. Compared to a standard temperature of 77 degrees Fahrenheit, a battery that hits freezing will typically produce 20 percent less energy, and at -22 degrees, the capacity can be cut in half.
This alternator may be rated for 110 amps, but it is not designed to deliver high current for an extended time. Test the recharge current as part of your overall charging system analysis.
But it’s not just the cold. According to a 2010 Battery Council International (BCI) failure mode study, even though batteries have become more heat tolerant over the last decade or so, heat can still have a drastic impact on the life of the battery. Back in 2000, a change of just 12 degrees Fahrenheit took roughly one year off of the battery’s estimated lifespan. In 2010, it takes a 22-degree change to have the same impact. Overall, improvements in battery design have resulted in an average lifespan of roughly 55 months (compared with an average of 41 months during in the 2000 study). And you might be surprised to learn that batteries in the South are used up (with an average of 47 months) long before their northern cousins (averaging 59 months).
To help make sure your customer’s battery will deliver as promised, perform a complete battery/charging system test. All you’ll need to do a complete set of tests is a digital multimeter (DMM) and an amp clamp.
The battery might start the car fine while the weather is warm, but any weakness in it will be magnified when the mercury heads south.
Start by measuring the Open Circuit Voltage (OCV) of the battery. A fully charged battery with healthy electrolyte should read 12.66 volts (2.11 volts per cell). This is an indication of the state of charge of the battery. If your meter reads more than 12.8 volts, there is a surface charge on the battery. This also can tell us something about its condition. Surface charges higher than 13.5 volts or so can indicate that water has been depleted from the electrolyte, due to evaporation or overheating. If the fluid level has dropped low enough to expose the plates even a little bit, it’s a good idea to replace the battery. If the plates are still submerged and you can access the cells, use a syringe to add water (distilled only please) to just below the vent well. A reading of 12.5 volts or less indicates a battery that is discharged more than 20 percent, and you must recharge the battery before proceeding with a load test. An OCV reading of less than 10.5 volts indicates a shorted cell and the battery should be replaced.
Be sure to test the battery connections. Look for (and clean) terminal corrosion and the battery case. Corrosion on the terminals is usually caused by outgassing of the electrolyte and might indicate a leak in the battery casing. Dirt and grease on the case (if it forms a path between the posts) can be a source of battery drain and accelerate the wear and tear on the battery. Perform a voltage drop test on both the positive side of the starter circuit (one lead at the positive post and one lead at the end of the starter cable where it attaches to the starter) and on the ground side of the same circuit (one lead at the negative battery post and the other on the starter case). Be sure to have an assistant crank the engine while you’re testing. Voltage drop tests must be done with the circuit on. Correct the cause of any excessive drop found.