Discharge/charge

[John Cornforth]

Well that's a puzzle. The Ammeter is a very simple thing, just a magnetised piece of metal (pole piece) with a pointer which reacts to the magnetic field created by the current in a short piece of conductor. Hard to see how the magnetism of the metal could have increased.

These things are hardly the last word in accuracy, but your sounds like it is miles off.

I don't suppose "someone" has combined the innards of a 10 A meter with the scale of a 20A one ?

Or maybe the needle works against a light spring which has weakened/broken ?

This article may shed some light: http://www.da7c.co.uk/technical_torque_a...r%202.html

[Bob Culver]

Diagnosis at a distance is certainly fraught! many are the tales of mechanics who have gone off on tangents after a chance comment. My neighbour spent a large sum with an auto electrician to fix what proved to be a blocked in line filter worth about $5! I gave him one and he changed himself.

[Nick Salmon]

Has indeed turned out to be a duff ammeter. I put in a replacement this morning and it works correctly.

Very grateful for all advice. Thank you.