I have a 32 fever with twin 502's, has 2 batteries on at all times and one that comes on with the key, most days the boat shoes 13-14volts crushing but today was showing 11-12 while idling or cruising. Is there a fuse somewhere for charging system? I dont believe both alternators would go bad but I've never seen it not above 12 while cruising. Thanks

I doubt it is a fuse. Time to start checking connections with a meter. Start with the two connections on your alternator, look for corrosion on the terminal and leads.

Only thing that stumps me is that it's a twin engine boat, why would both stop at the same time

Do you have both engines battery/alternator systems connected to each other thru the Perko switch(s) ?

Could easily be one connection knocked loose to do that.

Need to run one engine on "1" and one engine on "2". Running them on "ALL" is not advised.

I've owned it for 2 years and never have turned them off because it just never goes dead, they've always been left to all because it has a 3rd isolated battery.

One could have went bad a while ago and the other carried them. Now the other is going bad. Just a thought.

I had a conversation with an Alternator manufacturer a while back that does high end stuff for stereo competitions.....he told me that unless the alternators are specifically built for running with multiple units then what ends up happening is the voltage regulators inside the units will in essence fight each other. One alt will always be stronger then the other output wise...just the nature of having a mechanical thing working.....anyway they both will turn on but the stronger one will over power the weaker one and shut off the voltage reg on that one...then the stronger unit is forced to carry the load of the other system as well. (Seeing as most alternators are spec'd for only supporting one engine then have twice the load is hard on it.) Once the voltage hits its limit (and again your hoping the voltage regulators inside are equal which they never are) the primary unit will turn off....but if the secondary unit has a weaker setting then it will turn on and carry the loads....and you can get this cycling going back and forth eventually burning out one unit and then eventually the second unit when its tasked with 100% of the duty cycle...

So always run your batteries according to how they are wired....Motor running on its primary battery.....you will have to check with the Mfg on that cause I've seen some wired with motor 1 on position 1 and motor 2 on position 2 and I've seen others wired where the motors on each respective side is on position 1 and when you switch to position 2 it goes to the opposite side....gets very confusing going from boat to boat...

Maybe some applications. But on my cig. Battery must be on 1 and 1. To keep alternators from fighting each other. So not all systems are wired the same. this is wired this way from cig. I'd recommend the op do some research on his vessel and run his switches according to manufacture. Chech you're purple excite wire make sure not wired in parallel. Causing both alternators to loose the excite. Thanks