Why Won’t My MEAN WELL Battery Charger Turn Off?

15 November 2023

We were contacted by a customer, who had a MEAN WELL PB-600 series battery charger in his caravan.

Update: The MEAN WELL PB Series chargers have been discontinued from 2023 and replaced with the NPB series Battery Chargers. To learn more about the NPB series chargers, click here.


After replacing the batteries, he found that the charger was constantly running and wanted to know why it wasn’t shutting off.

The MEAN WELL PB-600 battery charger must be set to three-stage mode for caravan use.

MEAN WELL PB-600 Battery Charger
MEAN WELL PB-600 Battery Charger


It is a bit difficult to see which mode the battery charger is in, as the switch does not line up exactly with the numbers on the front panel.

The best way to tell is to move it with your thumbnail and feel it click into the three different positions. Three stage mode is the centre position. Turn off the main power switch at the rear of the battery charger before moving the mode switch.

The PB-600's fan does run continuously.

It will run fast if the charger is running in boost mode and will slow down when (and if) it goes into float mode.

The charger will start up and check the state of charge of the battery. If the battery is down on charge, it will go into boost mode and the fan will run fast. It should drop back to float mode after a while, depending on how much charge the batteries need.

If the batteries are flat, it will take quite a while. Also, if the fridge kicks in, or the lights are turned on, the charger will see this extra load and stay in boost mode, so the fan will run flat out.

If the load is still drawing power after 24 hours, the charger will drop back to float mode and stay there until the next time the power is cycled.

When the battery charger is in boost mode, the LED indicator will be orange. When it drops back to float mode, the LED indicator will be flashing green. Once the charger is in float mode, it will stay there until the power is cycled.

So long as you are getting these colours on your battery charger’s LED indicator, you know the battery charger is working correctly.

If you have any questions about using MEAN WELL battery chargers, please contact Power Supplies Australia.