I have a 10+ years old battery charger - Tecsup 24V 40A - installed. But alas no manuals, specifications etc. It appears to be a multi stage charger. When charging from the mains, everything is fine until it tries to switch to the lowest stage which I assume is a trickle charge. The charger then "pulses" (approx. 2x a second) as it tries to switch down - the last red indicator flashes on and off. This does not happen when charging from the generator. The only difference between the generator and the mains is that the generator is not earthed into the boat's common ground.
Before I spend lots of money on a replacement charger - simpler than trying to repair an out of date old fashioned charger, any ideas on what the problem might be?