Battery voltage
 

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

Rob, you are correct. One engine / one battery / not both.
Sorry, was referencing the OP's Fountain. ...assuming Fountain maintained their standard of switch wiring.

You are also correct that the alternator regulators will fight each other if on ALL or BOTH.

2 alternators should not be wired together.

When sitting can the batteries be switched to all? And just got home from Cumberland this morning and when starting to look around the starboard alternator has burned the stud in to on the alternator and the o-ring connextor in 2. The port motors is still attached

That is the result (high amperage situation) of the root cause. You can fix the alternator stud with disassembly, but you will still need to figure out why it was putting out so much amperage to damage the stud.

My guess (only) is that the other alternator may be weak, and the damaged alternator was trying to charge 3 batteries (due to running on ALL) and killed itself. If you are not comfortable with automotive (or boat) electrical systems, I would suggest that you have someone look at it for you. That could have easily caused a fire or worse.

Lastly, your volt meter should be reading at/near/slightly above 14 volts while running above idle speed.

When you say sitting I'm assuming you mean floating around not running or docked up to other boats and listening to music for extended periods of time?...then Yes you can have them all switched to all so you get 100% of all the power available....but keep in mind when switched to all you may kill all the batteries and not be able to start later. Also something else to keep in mind...if you have a battery with a bad/shorted cell and you switch to all, you can potentially kill the other batteries faster then expected

If they left the 32's the same one switch should be on 1 and the other 2.

When you say the third is isolated what kind of isolator? Which bat is it wired to? On 32's your port battery is the "house" battery or the one that runs your cabin stuff.

The 3rd battery is isolated by a solenoid that only connects when the key is turned on so if the other 2 are ran dead it has 1 to start with thats not been touched. While running it charges with the other 2. All the batteries are new this spring.

I wouldn't charge 2 let alone 3 batteries with the alternator. That is a good way to over load your alternator. You should have a separate 120v charger to charge batteries when you return back to dock/home. It is better to slow charge your batteries as well.

On your 32, put the port to 2 and the SB to 1. A simple way to think of it is as you are facing the motors, (facing to the rear) each switch should be pointed to the side of the boat it is on. That puts that switch on that motor. That keeps both motors and batterys isolated from each other. No reason to need a 3rd battery in a 32 unless you have a crazy azz power hungry stereo.

That's why we added the 3rd is because we go out all day and might not start it for 8 or 9 hours and wanted a battery that is always charged and ready to go. After taking both alternators off today it appears the main power wire was lose on both as they don't have any lock washers or nuts and the one that didn't burn the stud off about had the washer backed off it

I have run both single and twin engine 2 battery boats for 20 years. All boats had two batteries with one or two Perko switches with "1, ALL, 2, OFF " positions. I own three 2 battery boats right now that all get regular use. My experience is from a total of 8 different boats. Formulas, Fountains, Sea Ray, Marlago, Baja.

I have always used the same system: Battery switch(s) on 1 the first half of the outing, and on 2 the second half or on the way home. I make sure both batteries start BOTH of the engines, one at a time, on every outing or I charge or replace the low battery at first opportunity. I never use the BOTH or ALL position unless I have a problem starting which has been very rare over the years. For sure, absolutely, I have never had a problem using this system.

The only battery problems I get is when I pick up the boats after service it seems the repair people always leave the battery switches on ALL and I have had two dead batteries several times because of this nonsense. Now I check the switches before I even leave their parking lot and will make a comment about why I am getting into the boat!

As far as your charging voltages I would get a good quality meter with long 16-18 gauge leads clipped to each battery one at a time and watch the meter during operation to see if it agrees with your dash gauges. Check your ground and electrical connections - a bad ground can cause an otherwise inexplicable problem. And of course alternators and voltage regulators do fail, that's why the check while under way with a good meter.