Generator Battery Wiring- Crownline 270CR

[four winns 214]

My dock neighbor is a skilled physician, but knows almost nothing about the systems on his neglected boat that he has owned for three seasons. I rarely see him, but the other day he showed up and I attempted to help him understand some basics. He tried starting the Kohler generator, but the dedicated generator starting battery was dead. I checked it with a meter and it showed 9.6 volts. According to the warranty label, it was installed at the same time as the two starting batteries and they are functional.

I have not seen a wiring diagram or any documentation for the boat. The battery switch is the common Perko Off-1-All-2. There is an onboard battery charger and he keeps the boat on shore power. How is a generator battery typically integrated into the electrical system on this class of boat?

 

[alldodge]

As with most boat wiring it all depends on what this manufacture decided to do.

Some used isolators from the alternator to charge more then one battery when the boat is running. There should also be a multibank battery charger which is connected to each battery. That said my guess is Crownline didn't want to spend the extra money to install the correct charger, or the charger was replaced with one which did not have enough bank outputs

An easy fix would be to use a "Add a Battery" to one of the bats to charge it

 

[Silvertip]

So we have three batteries and one Perko switch that typically is designed to function with two batteries. There are many "creative" ways to work a third battery into the system but my crystal ball is broken so it's anyone's guess as to what was done. Done cheaply, the genset battery would be paralleled to one of the other batteries so it would charge any time the other battery was charged -- whether that was with a charger or when the engine was running. If the genset battery was dead but the starting batteries were both ok, then that indicates it was NOT paralleled. In fact it may not have been incorporated into the system at all relying solely on running the genset periodically to keep it charged. Does the boat have single, dual, triple or four outputs. Trace them and see where they go.