How to wire a raw water washdown pump on '94 270DA?

gengiant

New Member
Oct 5, 2006
268
Sacramento, CA
Boat Info
1994 270 DA
Engines
7.3L BRIII
So I spent my 4th in 104 degree heat installing a raw water washdown pump. I took my time with the install, wanting to make sure it ended up "professional looking". 2 trips to West Marine later (to get the correct fittings) I must say that it came out very well. I tee'd into the raw water supply to the head just past the strainer, ran a 3/4" hose to the pump that I mounted behind the hydraulic pump for the trim tabs on the starboard side at the transom. From there I ran a 3/4" hose up to the swim step. I mounted a quick-connect outlet on the gunnel side of the swim step. All hose connections are double-clamped.

The only thing left to do is the electrical work. I have a grey on/off toggle switch that I want to mount in the dash using the "auxilliary" switch location (currently un-used). I also have a 20 amp in-line fuse that I am supposed to locate on the "+" side of the power feed to the pump. My question is related to the power feed. :smt100 Is there a bus terminal that I can take power from to run to the dash or wil I need to run the feed all the way from the battery to the dash? If there is a bus terminal, where might it be located (I admit, I haven't yet looked myself). Lastly, to close the loop, is grounding of the "-" wire to the engine block all that is required? Or do I need to run that wire back to the battery and then have a separate grounding wire to the block? :smt017 I think all that's needed is the engine ground, but I really don't know. So any helpful hints and guidance would be much appreciated!

Regards,
 
There are both buses "-" and "+" under dash, but why you want to put switch on dash?
Raw water flush is design to be used on demand. You don't want to go and flip switch on dash every time you want to flush toilet. It should be mounted in the head.
 
GG, I would take a look at how your regular water system pump is wired for clues. You probably already know that it has its own circuit breaker and on/off switch. The breaker for it is a 10 amp breaker.

I know that there is at least one bus bar, and I think more, in the engine compartment, maybe fairly high up on the transom. That or those are probably for battery return connections. But you should trace out some wires to verify the use.

I would try and connect the return to a battery negative bus bar.
 
boatmailster said:
There are both buses "-" and "+" under dash, but why you want to put switch on dash?
Raw water flush is design to be used on demand. You don't want to go and flip switch on dash every time you want to flush toilet. It should be mounted in the head.

boatmailster,

I hear what you are saying, though we may be talking about slightly different applications here. I actually have considered mounting the switch for the pump near the outlet. Would seem to make perfect sense, reduce the length of the wiring runs and simplify fishing wires from the power source to the pump, etc. I may just have to do a little more research on the types of on/off switches that are available. I suppose it would have to be weather resistant as well as protected somehow from accidental switching from bumps, etc. The reason I had originally thought about mounting it in the dash was that I do have an unused accessory switch location in the dash panel, thus mounting it there would keep everything clean and uncluttered. But it would definitly defeat the purpose of convenient access to it on demand.

Dave,

Good idea about tracing some of the wiring of my existing pumps! :smt038 At least now I know why you know your boat's electrical system inside out! :wink: I will look for both "+" and "-" bus bars. That would definitely make for cleaner wiring.
 
If it were me, I'd install a 20amp breaker in the power panel located in the bilge and wire directly to that. Then you wouldn't need the fuse and there should be plenty of current available there.
 
MLauman said:
If it were me, I'd install a 20amp breaker in the power panel located in the bilge and wire directly to that. Then you wouldn't need the fuse and there should be plenty of current available there.

Dave M. suggested likewise in a PM. He thought that there was an unused breaker slot in the existing panel - I'll have to check on that. If that is indeed the case, would that slot be pre-wired? How could I check that?

Boy, these types of projects really point out what little I know in detail about these things! :smt101
 
gengiant said:
Dave M. suggested likewise in a PM. He thought that there was an unused breaker slot in the existing panel - I'll have to check on that. If that is indeed the case, would that slot be pre-wired? How could I check that?

Boy, these types of projects really point out what little I know in detail about these things! :smt101

No, there's really nothing to prewire to until you install the breaker. The breakers are 'Klixon' brand and have a big red reset button. IIRC, they fit thru a round hole that has a knockout plug in it. You probably have at least one (maybe more) unused holes (what Dave M is referring to). Inside the box, the wiring scheme is very easy to decipher. All the breakers just daisy-chain the supply side and you can just add yours to the end of the line.

Of course, you need to disconnect the battery(s) before going inside the box. Depending on how yours is wired, some of the power may or may not be routed thru the battery switch.

Theres a good negative buss (terminal strip) mounted on the transom on my boat - I assume you have this also. It would probably be your closest point for the neg connection.
 
gengiant said:
boatmailster said:
There are both buses "-" and "+" under dash, but why you want to put switch on dash?
Raw water flush is design to be used on demand. You don't want to go and flip ......................pumps! :smt038 At least now I know why you know your boat's electrical system inside out! :wink: I will look for both "+" and "-" bus bars. That would definitely make for cleaner wiring.
Any boat dealer should carry rubber bots for toggle switches.
You need to use good quality switch rated about 15-20 A or will burn-out quickly. You can use horn momentarilly dash switch used on many searays (the toggle one with rubber bot not the red one)
or use original searay panel with "ignition" switch used on smaller boats with mascerator
 
GG, I think there is some confusion here. It may be only me. But I recall only writing to you about using the breaker panel at the dash. I thought about what MLauman is saying, but I don't think I wrote it. The panel he is talking about is the one in the bilge, port side, just ahead of the batteries. It surely has some spare positions. I think it also is an enclosed box with room inside, if memory serves me right.

He is right that it uses the Klixon type breakers. The wire is probably easier to daisy chain there than at the breaker panel at the dash. I don't agree with the idea of using only the Klixon, and not using the fuse. I think the fuse would have a much faster response time to blow. Well, for a pump, maybe it is a stretch. Klixons are common there, as you don't want to blow on the start-up current spike, you want to trip on continued over-current. But I guess I just like to use what the manufacturer includes, even if it is redundant. But anyway, I think there is space for a fuse at that panel in the bilge. I know in mine, there is a fuse mounted outside the panel, but both ends of the wire are inside the panel. Right now I have forgotten what it powers, maybe the Mercathode system.

Voltage drop would also be less if you use the bilge panel. As we have discussed, it is bad enough at the helm already.
 
MLauman said:
Inside the box, the wiring scheme is very easy to decipher. All the breakers just daisy-chain the supply side and you can just add yours to the end of the line.

Of course, you need to disconnect the battery(s) before going inside the box. Depending on how yours is wired, some of the power may or may not be routed thru the battery switch.

GG, you may not find this to be true. I have the diode isolator mod, as you have. Mine does have daisy chaining of three of the four breakers in the box in the bilge. It is not very easy to look at and understand. It took me a bit of "hand over handing" to figure it out.

I was going to tell you how mine was wired, but I can't do it from memory and the photos I have, I need a drawing. I will say it has wire connections in splices that are somewhat hidden in wire coverings.

I was thinking that in all our boats, there needed to be two outputs from the converter, and these needed to go to each of the two batteries. But for my boat that is not true. I only use one Converter output; it charges battery #1. The output for battery #2 is cut back and taped off. It is not used. I have a charger/inverter on battery bank #2, and that charges bank #2, the house battery, when on AC.

You may want to post more of your thoughts or configuration. I don't remember if you have a charger/inverter on bank #2. But I have discussed the boat wiring in this area with MLauman before, and he has good insight, and good ideas about it. The 'as built' configuration is certainly amenable to improvement.

This is not a well written post, it is late and I am tired. But there is more for you to know about this bilge breaker box if you decide to use it. I have photos I can provide if you don't have quick access to your boat. My wiring is highly modified from original due to the diode isolators and the inverter/charger, but the breakers and layout are the same. Only the wires have been changed to protect the innocent.
 
Dave M. said:
I was thinking that in all our boats, there needed to be two outputs from the converter, and these needed to go to each of the two batteries. But for my boat that is not true. I only use one Converter output; it charges battery #1. The output for battery #2 is cut back and taped off. It is not used.

You should correct that. Leaving empty output on charger causing battery to being overcharged. You need to put jumper from empty output to output which charging battery. Otherwise charger "see" dead battery on empty charger post. on 3 banks charger all #posts should be jumped together.
 
In principle, I like MLauman's suggestion about adding a breaker to the breaker box in the bilge. This is along the lines of what I envisioned when I spoke of "clean" wiring". Like Dave M's boat, some of the wiring in mine was re-done under the previous ownership. Some of it seems to have been done professionally, such as the diode isolator. And then there is the "other stuff". :smt021 I've been straightening it out bit by bit as I come across it and as needed. (to date, I haven't spent any time to "decipher" any of it unless it was needed in order to overcome a problem).

As such, I don't have a clue as to how my charger/inverter is set up. I do know that it is not the original one. It got replaced with a commercial-duty unit. I've simply assumed that it was charging both batteries when on shore power. I guess I really should know what's going on "in there". :smt101 Oh well. Thankfully, I seem to be able to rely on friendly and helpful folks like yourselves here on CSR. Thank you all! :smt038

It will now be a couple of weeks until I will have time to mess with the boat again. I will post a follow-up on my findings after that. If, in the meantime, anyone has any additional suggestions, please keep them coming! I will print out this entire thread before my next 'venture'. And yes, I will absolutely disconnect both batteries before messing with any of the wiring! :wink:
 
GG,

Here is a link to a thread I posted a while back that shows the wiring modifications in my boat. Yours is probably very similar.

I see here that the diagram says the battery sense lead goes to bank 2. I wrote in the e-mail it probably went to bank 1. I suspect my diagram is correct. Since bank two is much larger than bank one, it is logical to sense the voltage there, its the biggest load through the isolator diodes.
 
Dave M. said:
GG,

Here is a link to a thread I posted a while back that shows the wiring modifications in my boat. Yours is probably very similar.

I see here that the diagram says the battery sense lead goes to bank 2. I wrote in the e-mail it probably went to bank 1. I suspect my diagram is correct. Since bank two is much larger than bank one, it is logical to sense the voltage there, its the biggest load through the isolator diodes.

Very interesting! I am surprised, however, that you'd run two 12V starter batteries. Then again, it doesn't get as cold here in Sacramento as it would up in Orgeon. As to the charger/inverter, I've often wondered if it'd be possible to replace the OEM converter. But I suppose that it would take some additional re-wiring throughout the boat to to so, such as the feed to the AC. But it sure would be nice to be able to plug into the cabin AC outlet when on the hook.

Lastly (and this is definitely off-topic, but since I started this thread....), what are the true advantages of two six-volt batteries in series vs a single 12V (other than the per-battery mobility benefits of the 6V's)? Do they have a higher capacity rating?
 
Just noticed a new ' Electrical Stuff' forum :thumbsup: Now, how do we get this moved over?
 
gengiant said:
Very interesting! I am surprised, however, that you'd run two 12V starter batteries. Then again, it doesn't get as cold here in Sacramento as it would up in Orgeon. As to the charger/inverter, I've often wondered if it'd be possible to replace the OEM converter. But I suppose that it would take some additional re-wiring throughout the boat to to so, such as the feed to the AC. But it sure would be nice to be able to plug into the cabin AC outlet when on the hook.

The boat was this way when I bought it. I think they just left the two existing starter batteries in place, and put them in parallel. No since changing what is already done, and it does give some more capacity. They are deep discharge batteries, so can be used in parallel with the golf cart batteries if desired. I don't think it was for cold weather.

Installing such a system is certainly possible. I am pretty sure mine was done after it was built.

gengiant said:
Lastly (and this is definitely off-topic, but since I started this thread....), what are the true advantages of two six-volt batteries in series vs a single 12V (other than the per-battery mobility benefits of the 6V's)? Do they have a higher capacity rating?
The 6V golf cart batteries are a high production item, so they are available fairly inexpensively. Having them have only 3 cells instead of 6 helps keep the weight down when you have to move them. It also gives more flexibility in mounting.

Very typically as battery amp hr size gets larger, the number of cells in a case decreases. When you get up to 800 or 1200 amp hours, normally you have a single cell per case. So it's also sort of a natural progression. It is sort of a safety issue too. Keeping the weight down makes them more managable, and less likely that you or your installer will get hurt. A 50 lb battery may not seem like an issue, but if you are installed a couple of dozen of 250 lb batteries, you get concerned about how to do it safely.
 
Dave M. said:
The 6V golf cart batteries are a high production item, so they are available fairly inexpensively. Having them have only 3 cells instead of 6 helps keep the weight down when you have to move them. It also gives more flexibility in mounting.

Very typically as battery amp hr size gets larger, the number of cells in a case decreases. When you get up to 800 or 1200 amp hours, normally you have a single cell per case. So it's also sort of a natural progression. It is sort of a safety issue too. Keeping the weight down makes them more managable, and less likely that you or your installer will get hurt. A 50 lb battery may not seem like an issue, but if you are installed a couple of dozen of 250 lb batteries, you get concerned about how to do it safely.

I do get and appreciate the weight and size issue, especially on boats when the battery mounting location isn't necessarily easy to reach - or a tight squeeze. But I have heard anecdotal evidence that two 6V batteries in series will have more a larger amp hr rating / capacity than a single 12V battery. I never understood that one and have read articles on the internet disputing this. Those articles mede reference to the number of cells and the size of each cell, stating that a single 12V battery could be built to the same capacity as two 6V batteries - albeit at twice the weight, thus potentially making the 12V battery unmanageable. So, other than the weight issue, are there any power or life span advantages to using 6V batteries?
 
GG, I don't think that having 6V per cell is any magic bullet. I think it is correct that you could build a 12V battery just the same, it would just be bigger. I think it is mostly economics. There are a lot of golf cart batteries in use, and they are made to be drawn down and recharged a lot of times. The construction of batteries can be tailored to all different sorts of uses. I think the 6V golf cart batteries are tailored for high amp hours and a lot of cycles. They are not specifically made to have a lot of cranking amps, that's not what they are for. So in reality, it may be that you would have to look long and hard to find a similarly built battery at 12V.

There is a slight disadvantage to using 6V batteries, and that is that you have two more battery terminals to maintain.
 
Dave M. said:
GG, I don't think that having 6V per cell is any magic bullet. I think it is correct that you could build a 12V battery just the same, it would just be bigger. I think it is mostly economics. There are a lot of golf cart batteries in use, and they are made to be drawn down and recharged a lot of times. The construction of batteries can be tailored to all different sorts of uses. I think the 6V golf cart batteries are tailored for high amp hours and a lot of cycles. They are not specifically made to have a lot of cranking amps, that's not what they are for. So in reality, it may be that you would have to look long and hard to find a similarly built battery at 12V.

There is a slight disadvantage to using 6V batteries, and that is that you have two more battery terminals to maintain.

Thanks Dave! Just the response I was looking for! As my house batteries will likely not make it beyond this season I think I might just have to consider replacing them with four 6V golf cart batteries. Are there any particular brands and/or models that anyone could recommend for this particular use (house battery bank)?
 

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