We have an ET4000 that is several years old but in good mechanical condition. Every morning after we unplug the batteries from the charger (and plug the batteries back into the lift) when attempting to use the lift we get an error code 40 on the LCD. This problem will continue for up to 15 minutes of repeated attempts to start using the lift (i.e. turning the key from the off position to the run position). Eventually the error code will stop showing up and we can use the lift the entire day without any further issue. This includes turning the lift off (key to off position) several times during the day. At the end of each day we disconnect the batteries from the lift and reconnect them to the charger. In the morning the entire processes repeats its self.