Newbie Maxum 3300 Electrical Questions

[billybatts299]

I just purchased a 2003 Maxum 3300 Twin 6.2 MPI with Generator. I am coming up from a cuddy cabin so I many questions.

First, Batteries- I have Port switch 1-2-Both-Off, Starboard 1-2-Both-Off. I am confused on the house battery. Are 1&2 both start batteries & the generator battery the "house battery"? Also I assume I should keep the battery switches to each engine (ie port batt 1 & Star batt 2) not always to both. Broker said always leave to both.

Second, Generator- Does the Generator Power the Shore 2 side of circuit breaker Panel? I assume the generator powers shore 2 then if the engines are not running I can use the parallel switch on the shore 2 side of Circuit breaker panel to link the 1&2 to power everything. I also assume that if engines are running & I start the generator just don't use parallel switch. That way engines do shore 1 side & generator does Shore 2 side.

Third, Battery charger- I turn on the Shore 1 & battery charger to keep batteries charged at the dock. When I run the engines I turn off the Shore 1, battery charger and turn on the ship power. Is this correct to not have on the battery charger when I am under engine power. I assume so because the alternators are now charging the batteries. Plus I thought i saw that the charger on while engines running could damage stuff.

Thanks for all your help!!

[mmwjr]

Nice boat.

Not sure but typically bank 2 of the batteries will start engine 2 and provide house power.

The generator will provide 110VAC and depending on parallel switch position will power shore 1 or 2 or both.

The engines can only provide 12VDC so no shore power from them.

Shore 1 will provide power to all 110VAC items when their breakers are on except the air conditioning with is the only thing on shore 2.

When the battery charger is on it should charge both banks of batteries.

[billybatts299]

Mike in regards to the battery charger do I need to turn it off when I run the engines?

[mmwjr]

Originally Posted by billybatts299

Mike in regards to the battery charger do I need to turn it off when I run the engines?

You should turn it off before disconnecting shore power.

[billybatts299]

Ok so I tested the Batteries and one failed. So I replaced both batteries and the generator battery is fine. What confuses me is both engines will start in the battery switch in the #1 & Both position but neither will start in the #2 position. In fact when trying to start batteries in #2 position the engines don't even try, no noise at all.

[mmwjr]

Under Documents of this site you will find the year 2000 manual for the 3300 and on page 53 it shows how the battery switch’s are wired. Looks like position 2 jumps port and starboard battery to the other switch.

[LeDeau]

Was wondering about that, I have a 3000 SCR. Do I need to switch the switches to off before connecting and disconnecting shore power?

[denemante]

Hi all - I know this post is nearing a year old, but I have a 2001 3300 SCR and I have very similar questions:

1. The previous owner left both switches to "both". I found the manual - it says to only do that in an emergency situation, but doesn't explain what that would be, or what another setting might be.

2. I have 3 batteries - 2 are situated port side, and one is starboard right next to the generator. I assumed the 3rd was for the genny, but maybe not. That could be for ship power, where the other two batteries are simply for starting engines. And perhaps the genny shares starting power from <one or two?> of the other two batteries.

3. Assuming those two batteries next to each other are meant for starting, does #1 match port and #2 match starboard? Perhaps it doesn't matter - maybe you don't want both switched to #1 (or both to #2), or both engines would pull starting power from that single battery. So it makes sense to leave both switches on "both" - like a single large battery for both engines, in case one grows weaker? But damn, why does the manual say not to have both on "both"?

[jparsons121]

I’ve never been a fan of Maxum’s choices in the DC wiring.
Each engine should be running off its own battery and it’s alternator charging the battery it ‘sees’ connected. Same for the genny. There isn’t a dedicated bank for house loads, one of the engine batteries shares the starting and house loads.

The Both setting allows for interconnect between both batteries, as the manual states.

[Captain John]

If you set the switches to "Both," one of your batteries could fail without you noticing it. In that scenario, when the second battery fails, you're screwed... Set one selector to Battery1 and the other to Battery2; if one battery fails, THEN you can set a selector to BOTH long enough to get engines running and move to a location where you can replace the defective battery. Cheers, Captain John

[yahoo82]

Something to be aware of, in my Maxum both switches had to be set to 1. #1 was “primary” which connected the output (engine/house) to the corresponding battery tied to the switch. The 2 was setup as a “secondary” jumper between the switches. In this setup you could either; 1) have each battery power it’s own loads. 2) choose either battery to power all loads or 3) choose both batteries to power all loads. I guess the benefit was if a battery was dead, you could completely remove it from the equation and connect everything to the single good battery, rather than the “both” setting allowing the dead battery to drag down the good one.


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[Trey5684]

BTW on my 3100se both batteries also use the 1 position, one switch for port engine and one switch for starboard engine. House load seems to be split between the two. Confusing but it works ok, boats seem to be like campers and often the same model is wired differently depending on year and who wired it. I think at times the dealer also enters into the equation.

[Uncleted]

On door where battery switch's are tells you, port on 1 and starboard on 2. Don't ask why because there are also several fuse behind the battery switch. Real stupid