I have searched for similar thread but cannot find anything on this topic.
My boat (new to me) has two house banks, each T105s, one bank is new and the other is about 6 years old. The older bank is reported by a battery shop to be toast, but seems to run the system for 24hrs no problem with a little help from solar. The batteries are charges by an older Guest 50 amp charger. Arriving at the boat following a week of shorepower, both banks read 12.8 with no load. Application of 7 amps, (reefer/lights) and the system voltage drops to anywhere from 11.5 to 12.2. Remove this load and system voltage increases back to original value.
Is this normal? If so, and realising accurate battery voltage requires 24 rest period, how can I determine when each bank has reached 12.2 (50%) charge?
Next purchase is a smart charger and two more 105s. At that time I will leave the house battery switch on both to essentially have one bank of 450 ah (225 usable)