I've installed a new generator and new start battery for the generator. I noticed when running, the battery voltage did not increase as it should - the generator has a 10A charger built in - but the battery slowly dropped down to 11.8V or so after a few runs. We diagnosed it to be the charger (it only has AC in and DC out so a simple device) so I ran a temporary cable and fuse from my new Multiplus 12/3000/120 trickle charger output to the battery while a new generator charger could be ordered. The negative side of all my battery banks (now 4) are all connected so I just ran a 14 AWG cable and a fuse from the Multi trickle output to the new generator battery. Without the battery attached I measured 13.something from the trickle output as I would expect, connected with the generator running I see ~3A draw. Over time the battery voltage increased to 12.7V. I've left the boat for 48 hours and expected to come back to a battery at 13.something - even at 3-4A trickle I believe the battery should be fully charged.
So....that's a long story to ask for opinions - should I expect the trickle charger to show 13+ volts on the start battery? My main house bank is fully charged from the Multi and is currently at 13.2V at a very small load. Is the trickle charger expected to be 0.5V lower than the main charger (think I read this somewhere) or could my new battery be at fault?
If the voltage drop is expected, then maybe everything is fine at 12.7V, it just seems wrong. There is painfully no documentation on how the trickle charger actually operates, so hoping to get some advice here.
