Here is a strange one. I have an Axon AX312 ammeter on my boat. Its 200 amp capacity. The highest service amperage is about 140 amps when the engines are charging low batteries. It replaced a similar unit that had stopped reading. The replacement was ok for a few weeks and then at switch on, it immediately read an amperage of around 150 amps (true amperage about 10 amps) and over a few seconds "counted up" to 199 amps before showing 1, which is presumably the beyond scale indication. All connections and attached loads were checked by an electrian and another replacement fitted, which after a few days of normal indications DID EXACTLY THE SAME THING.
Any ideas, please?