We're living in a UK marina for the winter, so I bought a 220 volt C-TEK M300 Smart Charger to keep the batteries topped up. When I first turned it on, it brought the system up to 14.7V and kept it there overnight until the batteries were fully charged. Then it went to float mode at a consistent 13.6V and stayed there for several days.

We went away for a week, and when we returned the charger had switched to a cycling mode where it goes to 14.7V for a time. Then it shuts off, the battery voltage gradually drops to 12.7 then the charger kicks in again bringing the system up to 14.7. It stays there for a time, adding a few Amps, then shuts down again. It cycles this way indefinitely. The instructions are pretty limited, but apparently this is the pulse maintenance charge.

This evening the charger has gone back to a steady 13.7V or so. The indicator lights on the charger haven't changed, they still show 'full battery maintenance charge'. According to the limited instructions, this phase might last for up to 10 days before going to the pulse mode.

I've never had a smart charger before. Is this pattern normal? Anything here I need to worry about besides checking the battery water? For background, it's a 480AH lead acid bank, new this spring, was never discharged more than 25%, and kept topped up by both solar and engine.

Thanks,
Max