Winter is a rough time of year for vehicles—particularly for their batteries and electrical systems. Because of this, there are two times a year that a truck should be checked over thoroughly; in the spring before the heat hits, and in the fall before the cold sets in.
After the first cold spell of the season, it’s common to hear people say things like, “That cold snap ruined my batteries!” But that’s not how it works. Hot weather is what ruins a battery, cold is just what makes it show up. When it’s a nice warm day, the batteries have a lot of capacity. They gain and output charge relatively easily—rather like pouring water into or out of a glass.
In the cold, however, batteries do not easily accept or release energy—more like the difficulty of squeezing cold toothpaste out of the tube, or, even worse, trying to get it back in. In the same way, the colder it gets, the harder is it to crank the engine. Weak batteries that worked fine in warm weather suddenly can’t provide the needed energy for cranking.
This can be seen if you look at the amp requirements for cranking in the cold versus when it’s warm; if the vehicle has 4 batteries and the current needed to start the engine is 760 amps, each battery should provide 190 amps of energy while starting. On a cold day, however, the current required could be 1600 amps or higher. This means each battery would need to contribute 400 amps—more than double the amps needed for a warm weather start.
In fact, if it’s cold enough, a driver can jumpstart a truck because of dead batteries, drive a couple hours, shut off the truck, and still have dead batteries because they were too cold to take a charge. Batteries will always have a harder time taking a charge in the winter than in the summer. So, if the batteries do die, they will need to be brought in and charged where it’s warm.
Because of the difficulty in charging cold batteries, another big thing to consider is trucks with EPU’s (electric power units) or battery powered air conditioning units. While these can reduce idle time, save fuel, and allow fleets to conform to anti-idle laws, they must be managed carefully. These are often set to run the batteries to a very low state of charge to give the truck the longest runtime possible off the batteries. This will negatively impact the battery life. As the batteries age and lose capacity, no-start events can easily result. Fleets should weigh the pros and cons and set this equipment up in such a way that they can find a happy medium between the two.
The bottom line is that before you spec batteries for your truck, you need to know what they’re going to be powering so you can make sure they’re not being overly depleted during the summer and causing issues during the winter. To prevent issues from coming up in the cold months, a fall PM check is crucial to keeping your trucks on the road.