We are frequently asked for tips on caring for batteries in cold weather. However, keeping your battery running at full capacity during the cold doesn’t start when the first frost hits. It actually starts when you’re deciding which battery to purchase in the first place. Choosing the appropriate battery is critical to your operation, and a little more involved than many people believe.
Often, people only look at the CCA. However, while that is important, it’s also important to pay attention to the reserve capacity and the cycling ability. If you only ever asked your batteries to crank the engine when they were at a high state of charge that would be one thing, but in cold weather batteries often power cab loads over night before cranking the engine in the morning. The colder the battery is, the less efficient it is. You need a battery that has enough power to power the loads and still have enough cold cranking power. You need a good balance between those and cycle life so that you know how many times the battery can be discharged and recharged.
Some common cranking amp ratings include CCA (cold cranking amps, test done at 0° F), cranking amp rating (test at 32° F), marine cranking amps (test at 72° F). Again, the colder the battery is, the less efficient is it. Sometimes battery companies make the cranking amp number in a bigger font to draw attention to it, and people tend to think “this is a big, bold number, so it must be a better battery,” but depending on your application it isn’t always the best number to look at.
One you have the right battery, it’s important to look at the age of the batteries. Most fleets running a bank of flooded cell batteries typically get an average battery life of 24 months. A bank of AGM batteries can have a battery life of double that of a flooded cell battery, depending on usage and application. The question then becomes; if you have a truck with batteries almost at the end of their life cycle and you’re going into winter, do you want to chance using batteries that are at the end of their life expectancy? That’s up to you; however, just remember that if your truck does have a problem, it’s cold out there!
The last reminder we give people about maintaining their batteries in the cold is to keep up on your preventative maintenance checks. Batteries (and the whole charging circuit, actually) should be checked twice a year—once in the fall before it gets cold and once in the spring before it gets hot. When performing the battery checks, make sure to clean the batteries at the same time. Batteries are often tested without the cleaning, which allows grime to build up around the terminals. Grime build-up allows a path for electrical flow, which in turn allows the batteries to self-discharge.
While you’re working on the batteries, test the cables as well. You could have the best batteries in the world, but if the cables can’t handle the energy from the battery to the starter and then from the alternator back to the batteries, you have a problem. Sometimes a cranking issue is actually a problem with the charging circuit because it can’t charge the batteries between stops.
According to TMC RP129, the preventative maintenance check should also include checking for voltage drop. You are allowed half of a volt drop for 500 amps for the cranking cables, and half of a volt at the alternator’s rated output (note: if your tractor has remote sense, you will need to test that wire as well to make sure that it is also working properly). The last part of the test is to test the alternator. Again, all of these tests should be done twice a year.
If you follow these guidelines, your batteries should be ready to go all winter long!