Your trucks battery state of charge may be good, but what about it's state of health? The state of charge or SoC is simply how much juice is in the battery. It's like your gas gauge. How full or empty is it? While the battery's state of health (SoH) lets you know how much life your battery has left. If the battery has 70% SoH, it can only old 70% of it's charge. You might think that's enough, but when you are trying to start a semi-truck in 30 degree weather, you're going to need your battery a little more livelier than that. When your mechanic performs your routine preventative maintenance, make sure they test for State of Health, along with State of Charge. It could mean the difference between starting your truck and getting on the road or calling your mechanic to give you a jump or even a worse, calling a tow truck.