Recently my system had been playing up. Towards the end of the day, on three different days, the pump had been stopping and starting, so by the time I've scrubbed the window, it's stopped and I have to wait 30 seconds or so and then it starts again for just about long enough to rinse. When I go back to the trailer, the pump controller is saying that the battery is at around 9.5V which would explain the problem, but two things don't make sense... 1. The battery has an inbuilt charge indicator that says it's fully charged 2. When I put multimeter on it it says 12.75V. I charge the battery after every working day with a charger that switches to a maintenance charge once the battery is full, the battery is only about a year old and I work part time so is hasn't been excessively used. Could it be a problem with the controller rather than the battery?