I don't know that I can add much to the specific problem you have been having, but would like to reiterate same situation as Dan encountered with wiring upgrade.
I had always had difficult time starting engine even with three 120 amp hour batteries switched to "all". I added the glow plug starter solenoid upgrade but it really didn't matter. I'd long ago bypassed the alternator output back to the amp meter gage on the engine panel and replaced it with a volt meter. It seemed the only thing left to do was to upgrade the battery wiring cables.
I decided there was nothing wrong with the existing #4 cables and would simply add parallel #4 cable alongside. As I proceeded, I made it a point to both solder and crimp the old as well as the new battery cable lugs. I used a propane torch and was able to effectively crimp the copper battery lugs with a pair of adjustable "Channelock" pliers- not perfect but got the job done.
I started at the batteries and worked my way through the bilge to the electrical panel and finally back to the engine. When I was done, I had used 75 ft ! of battery cable- I remember very well- two 25ft spools of black and one 25ft spool of red with only scraps not worth saving left over.
One of the very last connections I made was the ground on the engine block. I couldn't believe it, but i could literally pull the wire out of the battery lug it was so loose. This one connection alone was probably the source of all my problems.
After having made this one upgrade I have never had any qualms about battery usage, the need to upgrade the alternator, add more batteries, etc. The engine starts within a second at most, the cabin lights burn brighter, everything is so much improved, this is by far the single best upgrade I made in fifteen years of owning this boat.
I had always had difficult time starting engine even with three 120 amp hour batteries switched to "all". I added the glow plug starter solenoid upgrade but it really didn't matter. I'd long ago bypassed the alternator output back to the amp meter gage on the engine panel and replaced it with a volt meter. It seemed the only thing left to do was to upgrade the battery wiring cables.
I decided there was nothing wrong with the existing #4 cables and would simply add parallel #4 cable alongside. As I proceeded, I made it a point to both solder and crimp the old as well as the new battery cable lugs. I used a propane torch and was able to effectively crimp the copper battery lugs with a pair of adjustable "Channelock" pliers- not perfect but got the job done.
I started at the batteries and worked my way through the bilge to the electrical panel and finally back to the engine. When I was done, I had used 75 ft ! of battery cable- I remember very well- two 25ft spools of black and one 25ft spool of red with only scraps not worth saving left over.
One of the very last connections I made was the ground on the engine block. I couldn't believe it, but i could literally pull the wire out of the battery lug it was so loose. This one connection alone was probably the source of all my problems.
After having made this one upgrade I have never had any qualms about battery usage, the need to upgrade the alternator, add more batteries, etc. The engine starts within a second at most, the cabin lights burn brighter, everything is so much improved, this is by far the single best upgrade I made in fifteen years of owning this boat.