Which is the very reason that most of us are going away from Magnateks, IMHO.
Let me be clear that I wasn't finding fault with Magnetek (aka Parallax I believe), per se. The converter in question was from an early 1980's trailer, before the smart charging technology was available. I believe upgrade kits are available for Magneteks.
Point is, unless you pay the extra bucks for the multi-stage battery
charging function, a basic, run-of-the-mill converter makes a good power supply and a poor charger.