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Bilge pump alarm with internal automatic switch

chawk_man

Silver Medal Contributor
I have a Rule 1500 bilge pump with an internal automatic float switch. There is a ground lead, a constant hot lead wired directly to the battery, and a switched hot lead. I would like to wire in an alarm buzzer when the float switch is activated, but see no way to do that unless I get a new pump and external float switch. Am I correct in that assessment, or is there a trick that I haven't been able to come up with.

Also, the two hot leads are fused with the automotive type spade fuses. They are both 20 amps, which seems entirely too much. What would be the proper fuse?

Thanks for any help
 
Ayuh,.... Wire yer alarm into the ground lead....

The fuse only protects the wire, not the appliance,...
It oughta fine....
 
Bondo - Thanks. Just to be clear - are you saying to just cut the ground wire and connect each end to the alarm? I've tried to attach a diagram.

Bilge Pump Wiring Diagram.jpg
 
FYI: We see more issues with the pumps with integral float switches.
IMO, you are better off with a separate float switch, and one that is mounted at a higher elevation than the pump's lowest draw-down ability.
We want the float switch to be able to "open" the contacts and shut the pump off.

If this is a Main Bilge Pump, and if you moore the boat, be sure that the float switch's power is "Un-Interruptible".
 
Rick,

Thanks. Boat is a 25 ft C-Hawk which I keep on a lift most of the time. But during the winter, I trailer it to Hatteras and it is parked in a slip. Access to the bilge is extremely limited - everything I do in there is mostly by feel, thus the internal float switch. I did wire in the alarm as shown in the diagram I posted above, and it worked fine. BUT, then I looked at the wires to the alarm, and they are about 18 gauge - not nearly sufficient to carry the amps needed for the bilge pump. The bilge pump wires appear to be about 14 or 12 gauge. So, the situation is that I am interrupting the 14 gauge ground wire to the bilge pump with 18 gauge wires to the alarm. That is not good. So, now I need to find a work-around. The only thing I can think of is to find a heavy-duty alarm that will handle the amps. Any ideas on that?


My motivation for this is that I have an internal wash-down pump. Last winter off the Diamond Shoals, a 28 ft Grady White sank because the wash-down pump hose broke or came loose, and the occupants didn't know the boat was taking on water until it was too late. The were extemely lucky that a Coast Guard bouy tender was within 10 miles of them.
 
Yes, I do have several ideas that may help you.

Our Main Bilge pump is the pump that needs to be Float Switch powered, and IMO, the Float Switch will be powered via an "Un-Interruptible" power source!
(IOW, no means of accidentally cutting power to the float switch)

The Float Switch will conduct the POS side of the circuit to the pump (not the Negative).
This circuit does NOT need to run to the helm and back for any reason.... in fact, it's best if it does not.
It should make a direct path to the actual bilge pump.

The pump's Negative will go to System Negative Common.... (I.E., the Engine Block, or an off-engine Negative terminal block).

Now... the normal Manual On/Off helm switch (not Manual/Off/Auto sw) circuit will parallel this Float Switch "pump side" circuit.
The lead coming from the On/OFF helm switch also becomes HOT if/when the float switch was to power the pump.
This becomes an ideal location for a helm located alarm or buzzer.
There are NO back-feed issues to concern yourself with.

When wired correctly, this offers you:
**
Manual bilge pump operation via the On/Off helm switch.
**Automatic bigle pump operation via the Float Switch.
**No concerns that the Main Battery Selector Switch needs to be ON or OFF..... (the float will always have power available, until battery capacity is deminished)

**The alarm/buzzer is optional.


This image is just a suggestion, but gives an idea how to aquire uninterruptible float switch power (fused of course).
 

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Rick,
Thanks. That was very helpful. My current wiring setup is very similar to the one in the diagram with a hot lead from the house battery wired directly to the (internal) float switch, and a second switch hot lead which bypasses the internal float switch. It looks like I can install a separate float switch and wire it directly to the hot lead to the bilge pump, and bypass the internal float switch. Then, I can T the alarm between the float switch and the pump so it would activate whenever the float switch completed the circuit. So,that is what I will try to do. I notice that there are two types of float switches on the market. One is the lever type and one appears to be a sensor in a tube. Do you have a recommendation which works best? Also, what is the purpose of the 6V battery wired into the house battery? I’ve never seen that set up before.
 
Rick,
Thanks. That was very helpful.

1.... My current wiring setup is very similar to the one in the diagram with a hot lead from the house battery wired directly to the (internal) float switch, and a second switch hot lead which bypasses the internal float switch. It looks like I can install a separate float switch and wire it directly to the hot lead to the bilge pump, and bypass the internal float switch.

2.... Then, I can T the alarm between the float switch and the pump so it would activate whenever the float switch completed the circuit.

3.... I notice that there are two types of float switches on the market. One is the lever type and one appears to be a sensor in a tube. Do you have a recommendation which works best?

4.... Also, what is the purpose of the 6V battery wired into the house battery? I’ve never seen that set up before.
You are very welcome.... hope it was helpful, and not confusing!

1.... That should work just fine! You could just as easily not by-pass the internal float swith under the guise that the pump does not need to operate unless high water exists.
However, by-passing allows for an occasional pump test!
NOTE: the integral float switches can become gunked up, and may cause issues. It doesn't take much dried out bilge slime to prevent the operation of one...... hence the recommendation for the external float switch. :)


2.... Again, no need to!
The circuit from the manual helm switch becomes "live" when either the helm switch OR the float switch powers the bilge pump.
IOW, if you were to tap in right at the helm switch, this is schematically the same!

3.... I prefer the old school switch. It allows for an occasional manual operation as to check things.
Lift it up, and the pump should run!

4.... true well cell 6 volt deep cycle batteries (in series/groups of two) offer a greater amp hour capacity for our HLBBs (house load battery banks).
This is quite common amoung cruiser boats whereby house loads are a critical part of staying on the hook for any length of time.
I've been using them for years.

I have twin 5.7s.
The Stbd side battery bank also provides hull power.
I do not have a dedicated cranking bank for the Stbd engine.
I crank the Stbd engine on this large bank of 6 volt D/C batteries, and have had zero issues to date.
I know people who do same.

I do have a momentary helm switch "auto-combine" feature that would get me going should I end up with a low HLBB.

.
 
One other thought, if I may, and I'm rather anal on this, so forgive me if you will.
attachment.php


I despise direct battery connections, other than battery POS/NEG cables themselves.
Small wire terminals are prone to corrosion issues when made directly to our batteries.
These also lend themselves to being inadvertantly forgotten when doing battery R&R.
Yes, I know that the factory often sets these up this way! :mad: :mad:

We have the near perfect location for these right at the rear of our MBSS (main battery selector switch).
#1 and #2 will be un-interruptible...... the "common" will be interruptible.

We can connect to these (fused of course) and take power from any of these 3 terminals.

Switch-Back.jpg


If you will notice in my schematic, the O/B Charger leads also connect directly to the #1 and #2 terminals.
This is schematically identical, but avoids the direct battery connections.

Either works..... it's just a preference of mine! :cool:

.
 
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Rick - Good point. All of my ground wires are set up on a seperate terminal set, but not all the positive ones. That is a good suggestion, and I will do a re-work. Thanks.

Let me ask you another question. The fuses on several of the circuits on my boat use the automotive type spade fuses. I've often wondered if that is a good idea, and wouldn't it be better to replace those with the covered cylinder-type fuses. Your opinion?
 
I think that as long as each battery bank's Negative cable makes a direct engine block connection, and that you join the engines together with a heavy Neg cable....., you will be OK.
For any accessory system Negs, you can come from the the engine block to your (quote/unquote) "seperate terminal set".
I see no issues with that at all......... in fact, it's an excellent idea. :cool:
All too often owners place too many accessory circuits on the OEM hull harness! :mad:

This also keeps your Negs clean in the event that you would add a Xantrex LINK battery monitoring system in the future.
(this has to do with the Shunt Resistor's location)

y250
3-33711.gif




As for the fuse type/style, as long as the assembly is Marine, and not automotive, you will be OK.
(you'll want the Marine as to avoid corrosion/rust)
 
CHawk, yes..... Bob is correct. The alarm in your scenario (in the Negative path) would want to play the role of resistance....... similar to a light bulb in series with others!

This is a crude schematic, but shows how the pump would interface with both the helm switch and the float switch.
As suggested earlier, the alarm can be powered via this same lead.

If you wanted to eliminate the alarm during helm switch operation, a special helm switch could disrupt the alarm negative while in manual mode, then bring it back into the loop when off.
 

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