Maxum scr3700 - is there a ac to dc convertor - Maxum Boat Owners Club

tk4478 · 08-03-2021, 06:53 PM

Hey Everyone Im starting to have issue with my 12v system while my lights work great my bilges will not work of shore power, they only work while batteries are on.

I woke up this morning to a foot of water in the after cabin and the forward cabin bilge was full and almost about to hit my carpet. I checked all my breakers in the panel, under the steering wheel and in the cabinet with my battery switches everything was good. but the bilges were not running while connected to shore power with the batteries turned off

once I turned the batteries on the bilges turned on.

Where could I find the convertor to have to get it tested / replaced

mmwjr · 08-03-2021, 07:15 PM

The bilge pumps float switches should be wired so that the battery switches don’t need to be on. The helm switches should be wired through the battery switches. AC to DC converter would not be factory installed so if you have one it was added so it would hard for any of us to know where a previous owner may have installed it. Sounds like you have an leak issue to have that much water in 5he bilge to begin with.

tk4478 · 08-03-2021, 08:19 PM

correct me if im wrong but if your connected to shore power you shut off the batteries and then turn on the mains, which gives you your 110

how ever there lights in the over head are 12v and still work with the batteries off.

so with the batteries off what is running the 12v lights

mmwjr · 08-03-2021, 09:40 PM

Quote:

Originally Posted by tk4478

correct me if im wrong but if your connected to shore power you shut off the batteries and then turn on the mains, which gives you your 110

how ever there lights in the over head are 12v and still work with the batteries off.

so with the batteries off what is running the 12v lights

Yes shore power will provide 110VAC. Unless there is an inverter the batteries will still need to be switched on to have 12VDC. From your first post it seems like someone changed the factory wiring as your bilge pumps are not working automatically off their float switched. I have no idea why the cabin lights work with the batteries off which suggests to me that either they have been wired around the battery switches or an inverted was added by a previous owner. My point is it’s not OEM so you’ll have to figure it out yourself. I would look near the electrical panel for a inverter however if only the cabin lights work it’s not providing much 12V help.

tk4478 · 08-03-2021, 09:55 PM

I agree all the bilge pumps work just not with out the batteries on and that is where I am lost at this time.

sph801 · 08-03-2021, 10:07 PM

Like Mike said, the bilge pumps should be wired directly to the battery so that you can't turn this important piece of equipment off. The lights working with the battery switches off is strange and sounds like the previous owner changed something there. Where is all this water coming from?

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mmwjr · 08-03-2021, 10:42 PM

I may be wrong about the inverter. Under Documents of this site you will find the manual for the 2009 3700 and it shows the battery charger as a combined inverter. I didn’t spend much time reviewing to answer all of you questions but it should help you. BTY I would be most concerned testing/fixing the bilge pump float switches and determining how all that water is entering.

yahoo82 · 08-04-2021, 02:02 AM

Some battery chargers will supply 12v power even when not connected to the battery (some do not put out current until it “senses” it’s connected to the battery). So your charger is likely wired to the “house” or load side of the battery switch (which also means your batteries don’t charge when the switches are off). The battery charger running on shore power is supplying your 12v load to the boat even with the battery switch off.

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Trey5684 · 08-04-2021, 04:36 AM

Bilge pumps usually wired direct to battery so they work even with battery switch off., and have a instrument panel switch to allow manual operation of the pump.
As far as lights they are 12v and should not work with battery switches off.
Only speaking from the way my 3100se works.
As Mike said maybe some mod by previous owner.
Also look for the leak that seems like a lot of water.

Phillbo · 08-05-2021, 06:11 PM

That is one serious leak. I'd be pulling it out of the water if it's something like a bad bellow. Could be a fresh water tank leak.

If you are in salt water try tasting the water in the bilge to determine if it's an external or internal leak.