Parasitic Battery Drain: Causes and Solutions

Few things are as frustrating as dead batteries. It’s annoying to park a perfectly running truck at night only to find that it won’t even turn over in the morning. Often parasitic battery drain is to blame. It sounds more sinister than it is, though it is similar to the work leeches do. According to AxleAddict, parasitic battery drain is when power continues to be drained from batteries after the truck’s engine is off. It shortens battery life in the short term and for the long haul. The more you charge batteries, the quicker they die for good. However, like many common problems, battery drain is an issue you can avoid with a little proactive care.

What Causes Parasitic Battery Drain?

You’d think that when you turn a truck off, there would be no electrical load on the batteries. Sadly, that’s not the case. You could say technology is to blame, as TruckingInfo points out that today’s trucks use electronics all the time. Especially those that deal with hotel loads that cater to driver comfort. Coolers, microwaves, TVs, GPS units, lights—all these conveniences use battery power.

Sometimes, system parts bleed batteries dry, such as oil pumps. Manufacturers usually engineer trucks to offset these types of power draws, and manuals list maximum normal amounts.  Other times, system glitches drain battery power. For example, a trailer system circuit usually close once its own battery is fully charged. If it malfunctions, though, the circuit stays open and keeps drawing power from of the truck’s batteries.

Diagnosing and Solving the Issue

Digital multimeters are handy little tools for diagnosing  battery drain. They are as valuable as other heavy duty tools all techs need. To start, you connect them to the truck’s battery pack with the ignition off.  Once you turn the tool on, the reading will show whether there is too much draw on the batteries. It is the first step in solving the issue.

As for pinpointing where the drain is coming from, the old-school way is hit-and-miss.  It involves pulling out fuses—one at a time—to see which ones affect the reading. On the other hand, there’s software that finds problem circuits. These programs are invaluable as they save time.

Can you avoid parasitic battery drain entirely? Between necessary power draws, ones caused by comfort features, and faulty equipment, the answer is no. However, you can reduce it as much as possible. Try unplugging optional equipment when drivers park their trucks for the night. That includes cell phones and chargers. This is especially important when they’re finished driving for several days. Additionally, report even the smallest electrical issues to the maintenance team.

Finally, maintenance teams should add checking for battery draw to their regular routine. With everyone keeping an eye out for possible parasitic battery drain problems and causes, fewer drivers will face the frustration of dead batteries.