Bilge pump and alarm circuit

We have a situation where one of the house batteries on our Mainship 430 Aft Cabin would run down when on the hard, even with all breakers turned off. It was discovered that 4 little relays were wired directly to the battery and there was sufficient current draw to drain the battery over a couple of days. Upon investigation, it appears that when any circuit in the bank of relays feeding the bilge pumps is broken, the relay powers up a main wire that sends current to a second bank of relays that fires up ALL of the bilge pumps and alarms. My yard says they've never seen a setup like this. Is anyone familiar with this type of redundant circuitry? Is this standard Mainship? Does anyone else have problems with drained batteries like this?

That does sound like a weird way to wire the bilge pumps, but why don't you just disconnect your batteries while on the hard. There is always some small load like a CO2 detector that will run them down.


David

TJ Sprocket said:

We have a situation where one of the house batteries on our Mainship 430 Aft Cabin would run down when on the hard, even with all breakers turned off. It was discovered that 4 little relays were wired directly to the battery and there was sufficient current draw to drain the battery over a couple of days. Upon investigation, it appears that when any circuit in the bank of relays feeding the bilge pumps is broken, the relay powers up a main wire that sends current to a second bank of relays that fires up ALL of the bilge pumps and alarms. My yard says they've never seen a setup like this. Is anyone familiar with this type of redundant circuitry? Is this standard Mainship? Does anyone else have problems with drained batteries like this?

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TJ Sproket
I don’t know how your alarm is wired but it looks like MS standard.
On mine 400/2005 I have 8 relayes for four pumps and 3 or 4 buzzers. For me it looks like a good failsafe system.
A tricky thing is that there is a hidden fuse (on a wire ~5A) inside the main fuseboard.
I have made a drawing over my system and shared it on the Trawler forum about a year ago.
Maybe it could be some help for you.
boan

Thanks Boan. Glad to hear that it is standard. I’ll search for your wiring diagram and compare it to mine. Thanks for the heads up on the fuse. By the way, then, do you just disconnect the batteries when on the hard or do you have a switch somewhere?
TJ

TJ Sprocket said:

We have a situation where one of the house batteries on our Mainship 430 Aft Cabin would run down when on the hard, even with all breakers turned off. It was discovered that 4 little relays were wired directly to the battery and there was sufficient current draw to drain the battery over a couple of days. Upon investigation, it appears that when any circuit in the bank of relays feeding the bilge pumps is broken, the relay powers up a main wire that sends current to a second bank of relays that fires up ALL of the bilge pumps and alarms. My yard says they've never seen a setup like this. Is anyone familiar with this type of redundant circuitry? Is this standard Mainship? Does anyone else have problems with drained batteries like this?

Click to expand...

The concept is sound, unfortunately some relays have to stay energized hence the drain. I had similar set up on previous boat, I installed small dedicated Bilge Pump Panel and replaced the whole ( relay ) thing by drawing from both banks via 2 @ Schottky Diodes. ( low forward voltage drop as opposed to standard PN junction type diodes, and only the battery with higher voltage supplies the power to pumps. Draw on the batteries is only ... when pumps are running )

Worked for me ! .... f

First winter we owned the boat, I thought I’d shut everything down and left the batteries connected while on the hard. When I checked them a month later—after a major cold snap—I discovered I’d killed four 8-D AGMs due to parasitic loads—one of which was an auto-sensing bilge pump. The last three winters we had the boat on the hard, everything was disconnected and the new AGMs did just fine.

The following pic is representative as to what I had on my 2003 Mainship Pilot 34:




The normal bilge pumps were wired this way with the three way switch and the light being on the DC panel (on, off and float switched). The high level pump was wired similarly but without the three way switch and a buzzer was in parallel with the light. I think there was a spst switch that silenced the buzzer.


So if your high level pump works but the buzzer doesn't sound, look at the wiring to that part. You may have a bad connection. Also check to see if there is voltage across the buzzer when the pump is on. Maybe the buzzer has failed.


David

I had done some electrical troubleshooting on a Mainship 390 single Yanmar. I found the electrical system unnecessarily complex and confusing. It might have been due to thrusters being added later, that was not clear. Big battery cables running everywhere, important electrical things hidden in weird compartments, switches and fuses not labeled, switches that did not really serve their labeled function, etc. Had a devil of a time with it.

TJ, can you tell me where you found the relays? I haven't found anything like that in the bilge pump circuit of our 2003 Mainship 430.

TJ Sprocket said:

Thanks Boan. Glad to hear that it is standard. I’ll search for your wiring diagram and compare it to mine. Thanks for the heads up on the fuse. By the way, then, do you just disconnect the batteries when on the hard or do you have a switch somewhere?
TJ

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TJ Sprocket
Switch is not good of safety reason. Easy to forget. No I never disconnect the batteries. I’m able to charge on hard.
But if not, disconnect the batt-banks to be sure.
boan

On my 2005 34T: 3 normal bilge pumps with indicator lights operate independently. If one lifts the Hi level float switch, it brings an audible alarm and indicator lights showing that all 4 pumps are operating, but only the hi level pump is actually running. The alarm circuit is very complicated and includes 4 interconnected relays. If one particular relay hangs, the alarm will stay in while while no pumps run.

As a follow up to posts above, here is latest from my guys at the boat:
"this (the pic from DJMarchand, above) is not representative of what you have on your boat fully. The above picture is a "normal", and appropriate setup, and in fact represents PART of what you have. In your current setup, the alarm wiring is such that if you lose power to ANY one of the bilge pump circuits, ALL of the remaining bilge pumps and their alarms are energized. There is no way to mute those alarms or turn them off. We installed a "layup" switch to accomplish this when laying the boat up. However, this switch also disables the high water alarms and manual power switches for the high water pump. So this is not a good solution during the season. As an additional factor, the layup switch disables the CO monitor as well."

batteries

I have a 40 ft 2007 mainship trawler I have it stored in the water for the winter. I found my batteries very low in water and not putting out any voltage.This happen after 3 weeks of sitting there. The charge was on the whole time.Could this pump problem you are talking about be the cause? If so where would I find these relays and inline fuse and how could I test this. Tom