Bilge pump wiring

[Michael Abramson]

Is it normal that the bilge pump is wired in such a way as to only draw from the #2 battery, assuming #1 battery is the main starting battery? I guess I always assumed the pump, as a safety component, would use either/both batteries.

If a sealed battery has been fully discharged, how does one check the electrolyte is sufficient to recharge it using a step-down charger?

Thanks.

Michael

[Steve Laume]

You don't want to keep your batteries interconnected or they will slowly but constantly draw each other down. The bilge pump wiring would do this if it was connected to both batteries before the selector switch. Not only that, but it would be connected by a very light wire relative to general battery loads. If you were to select one of your batteries and then start the engine with the bilge pump wired to both the contribution from the unselected battery would try to flow through the light wire.

If you are always using one battery to start then it would make sense to wire the bilge pump to the other battery. From a safety point of view it would not do you much good to have the bilge pump draw down both batteries and be left with no way to start the engine.

Have you experienced any problems with the way the wiring is currently set up?

One of these days I will set up that emergency electric bilge pump I had planned to install this spring, Steve.

[Neil Gordon]

If you are always using one battery to start then it would make sense to wire the bilge pump to the other battery. From a safety point of view it would not do you much good to have the bilge pump draw down both batteries and be left with no way to start the engine...

One of these days I will set up that emergency electric bilge pump I had planned to install this spring, Steve.

If you're thinking (i) smaller pump lower down to take care of seepage, plus (ii) larger pump higher up to handle flooding...

Then assuming two deep cycle batteries (which is what I have rather than a dedicated starting battery), I'd wire one pump to one and one to the other. That would give you max pump life if you're not there. If you are there, chances are you'll either stem the flow or sink before both batteries are drawn down so starting the motor (assuming you're still floating) shouldn't be a problem.

[Michael Abramson]

Thanks, Steve. Your answer makes a good point that I had not thought about. I can see now the pump needs to be connected to one battery or the other after the battery selector switch.

My schematic shows no bilge pump wiring, and I have not tried to trace the wire bundle in my bilge, which seems to contain too many wires and connections than would seem necessary. I'll google the subject and see if I can find a typical pump/float switch setup and then compare that to mine. I'll have to make a test lamp with very long leads to check the wire runs.

I use a small micro charger, a $5 item from Harbor Freight, to charge the battery over the winter. I used to move it back and forth from #1 to #2, but apparently forgot to do so recently and let #2 totally discharge, leaving me with no functioning bilge pump. I think I'll either use a second charger on #2 battery, after disconnecting it from the battery bank, or take the battery home over the winter and keep it in a warmer place on an occasional charge.

Thanks for the insight.

[Steve Laume]

Thanks, Steve. Your answer makes a good point that I had not thought about. I can see now the pump needs to be connected to one battery or the other after the battery selector switch.

Thanks for the insight.

If you are connecting to one battery or the other, you can do it before the battery selector. This is in fact preferable in that you can keep your main selector switch off. A fuse near the battery will protect the wiring to the bilge pump.

If you want to be able to use either or both batteries for your pump, then you would tap into your power supply after the selector switch.

I want a pump that could attempt to keep up with something bad that might happen while I am aboard and attempting to stop the flow. This might be something that takes a while or could not be completely remedied. In that case I would want to be able to start my engine even if the battery was being drawn down by the pump.

Foremost is a good manual bilge pump, Steve.

[Michael Abramson]

Steve

I have never had to have my battery switch in the ON position(s) for my bilge pump to work. I have a small 3 way pump switch that is Manual/Off/Auto, and normally that is in Auto position, so that would mean that it is hot direct from the battery, in my case #2.

However, I know there is no separate lead to battery #2, so maybe the hot lead to the switch is energized where the battery + cable connects to the main battery switch. Does that make sense?

Any other likely scenarios for how it is wired?

Michael

[Steve Laume]

It sounds like all is well. The bilge pump switch could be taking it's power off of the terminal at the selector switch or the battery post. Maybe even a terminal block that runs to one of those locations.

You just don't want to tie the two batteries together with the bilge pump wiring.

Your system sounds fine, Steve.

[mattlydon]

Don Casey recommends, and I like his thinking:

1 small automatic bilge pump, wired direct to one battery, to take care of seepage.

A second, VERY LARGE, bilge pump, connected after the selector switch, on a very obvious stand-alone switch near the companionway.

The idea being, if you should have a small leak, the small pump will take care of it, and, more importantly, run for a considerable length of time before running the battery down. If the boat does start to sink, and someone spots it and gets on board, you have the big pump to bail you out, and you can select a charged up battery to run it on.

If you had everything automatic, the pumps would run until the batteries ran down, and then your boat would sink with dead batteries and no chance to recover.

Also, if you're cruising, and get holed by something large, you have the option of switching from one battery to the other at need, which you can't do if they're hard-wired. (imagine taking on 10 gpm where your 5 gpm pump's battery is peachy, and your 20 gpm pump's battery is dead.

Matt

Matt

[Jim Davis]

Personally I like two pumps. A small one for keeping the bilge somewhat dry and a large one with its switch mounted on a block about two inches above the small one. This way the big pump does not come on except when the small one can't do the job. Both are with float switches and after the selector switch.

I also have a couple heavy duty manual pumps, one fixed, the other portable.

[Neil Gordon]

Don Casey recommends, and I like his thinking:

1 small automatic bilge pump, wired direct to one battery, to take care of seepage.

A second, VERY LARGE, bilge pump, connected after the selector switch, on a very obvious stand-alone switch near the companionway.

This all depends on whether you expect to be on your boat when it begins to sink. If you are, you can manually engage the pump using the best available battery or switching when need be. But if you're not, you want the larger bilge pump to kick in and keep the boat floating. Note that a very loud alarm should sound if the second pump kicks in. Otherwise, the pump will work silently until the battery dies, then the boat will sink anyway.

[Steve Laume]

Okay, so being generous, lets say my older battery bank has a 150 amp hour, usable, capacity. I install a nice big 2000 GPH pump and something goes horribly wrong.

Of course this would happen at the end of the season when the launch is only running weekends and not many people are at their boats during the week.

So a hose lets go at 7 PM. The pump starts pumping and the alarm is buzzing for all they are worth. From the shore the alarm is just some far off annoyance. It is going to be dark in a half hour or so, not nearly enough time for even the most curious to investigate.

So our trusty pump and alarm work all night long at about 15 Amps combined. By morning to boat is going down, if not already there. Without the alarm it would take slightly longer but people would be even less likely to notice.

This is not a far fetched scenario. We all know things happen at the worst possible times.

Raven does not currently have an electric bilge pump. She does have a new Whale Gusher 10 and another portable manual mounted on a board. We also have buckets.

I do plan to install large electric pump this winter but it will be set up for use in case of an emergency while I am on board. This is the most likely time for an emergency to occur. The pump will work to keep up with the water while I am then free to fix the problem.

Any debris or faulty float switch will drastically effect the above results, Steve.

[John R.]

This is a controversial subject because there is certainly more than one approach to dealing with a a leak or flooding boat.

Steve, you already have the best pump in the world assuming you are on board - the buckets. The old saying is very true that the best pump in the world is a scared sailor with a bucket.

My view has always been to run a single automatic pump on a non mechanical sensing float switch wired through a typical mom/ off/ on switch with visual activity indicator (lamp of choice). I always wire that system direct to the battery selector switch common terminal. The system is them powered by the batt switch left on bank 2 (house). I would use a high and dry ITT Par diaphram pump as a primary so there was minimal chance of a clog when no one was onboard. That pump filtered through a water strainer such as a Vetus raw strainer that had plenty of capacity to catch debris without clogging. In case small debris would get past the strainer the diaphram design of the pump would pass small debris easily and not jam like a centrifigul can. As a emergency pump system I would generally install a Rule (dependable) high capacity (2400 gph or more)in a deep area of the bilge. That pump would be wired to a independent manual emergency bilge switch and was wired direct through a remote circuit breaker and direct to the house bank.

In addition, on my own boat I have a manual gusher in the cockpit, a diverter on the engine intake, and a diverter on the shower sump pump. All can be used in unison with a big bucket and a scared sailor.

Good luck in your design.

[Bob Owens]

Professional marine electrician wired my bilge pump exactly as Steve describes, using #2 (house) battery only, upstream of battery switch, but with manual over-ride switch on the main electrical panel.
Bob