One problem with the lights that’s particularly common with older RVs is low voltage to the headlights when under load.  Many motorhomes use an isolator between the alternator and battery, which costs you about 0.6-0.7V, and many also run power from the headlights through the headlight and dimmer switches.

It’s not uncommon to see only 10V at the headlights.  While that might seem like most of 12V, consider that power goes with the square of voltage–compared to a normal 14V system, your lights at 10V would only be half as bright!

Continue reading Testing to determine whether headlights are operating at full power →