When designing our latest battery charger line, we made a deliberate engineering decision: the battery voltage test function only operates when shore power is connected. This was not an oversight — it was a purposeful move to eliminate parasitic battery draw and protect battery health in real-world trailer use.
Parasitic draw refers to the small, continuous electrical load that slowly pulls power from a battery when equipment is idle. While the draw from monitoring circuits and voltage testers may seem insignificant, it can noticeably reduce battery voltage between uses — even over just a few days. This is a leading cause of weak or dead batteries in trailers that are used weekly but not plugged in every night.
Many traditional chargers and always-on battery testers keep internal circuits energized at all times. Over short idle periods, this continuous drain can leave users with batteries that are unexpectedly low when they need them most. Over time, parasitic draw accelerates battery wear, increases sulfation, and shortens overall battery lifespan.
Our approach is different. We designed our chargers with one guiding principle: a charger should only deliver power to a battery — never quietly take it away. By allowing voltage testing only when shore power is present, the charger remains electrically dormant when unplugged, resulting in zero battery draw during storage or between jobs.
This design is especially important for dump trailers, utility trailers, and equipment trailers that frequently sit unplugged between workdays. Eliminating parasitic draw helps preserve battery charge, improves reliability, and reduces the frustration of mystery dead batteries.
For a deeper explanation of parasitic draw and how it affects trailer batteries in real-world conditions,
Read our original article here: Parasitic Draw Impact on Trailer Batteries.
Our charger design reflects intentional engineering focused on battery longevity, reliability, and real trailer use — not just convenience. When shore power is connected, testing is available. When it’s not, your battery is protected.
Written by Donnie Gagnon, Primary Mover, Product Procurer
Primary Mover designs and supplies mobile hydraulic and auxiliary battery maintenance systems built for real work environments. As a one-stop shop for hydraulic dump bed hoists, cylinders, pumps, jacks, hoses, fittings, and battery charging solutions, our focus is on reliability, efficiency, and equipment that lasts longer with less downtime.