have a 2001 43foot open thats losing voltage to starters,batteries are 31 size gel type and are newer,being told by tech that the positive side cables run are way too long,have been parralleling to get easy starting.total 8 31 batteries,four for starting,any input would be appreciated,3196 cats.
I had the same issue on my 43 Open/3196. Had to parallel all the batteries and it still rolled slow and reset all my electronics due to voltage drop even with new batteries. I visually checked the battery cables which were quite large in diameter, presumably to accommodate the longer cable runs?
I always assumed (and I certainly could be wrong) this was a result of Tiara opting for a 12V instead of a 24v system on 3196 boats. I believe 12V requires twice the current/amperage as a 24V. By way of comparison my current boat has 3406 engines (24v electrical) that have never required parallel. Larger engine requiring less power with battery cables equal or longer than what was on my 43 open. At least that's my thinking.
There are tests you can do with a DMV whereby you check cranking voltage at each battery post and then at starter. The boatdiesel forums will tell you allowable voltage drop and percent across each terminal. I think if you see a noticeable drop in voltage at any one battery terminal it indicates a bad connection or bad wire upstream.
Is this a new problem or have you always had to do this? If it is new I would suspect either a bad battery or cable. If one of the cables is separating internally or has some corrosion wicking up it, that can cause all sorts of problems. Especially under a starter load.