Electrical Upgrades

[IpswichGrady]

Thanks for the input. I definitely think I may be overthinking the whole setup. I am a firm believer in K-I-S-S because when you get fancy then there are more chances something will go wrong.

I started adding up amperes of different accessories. I had no idea how few amps some of these electronics draw. And that brings up a question... should I not even go 50A breaker... drop down to 30A and if I end up adding anything later which requires a new line just run it then? Believe me there will not be an AC or refrigerator..... nothing to draw any major amps.

I'll put together my schematic and show what I have in mind.

 

[IpswichGrady]

This is my start... I'll add more and label with time.

 

[seasick]

30A is fine if no windlass. Your diagram looks ok based on a brief look. I cant see some of the small print (old age).

Remember that the feed to the automatic wire on the bilge pump connects directly to one of the batteries. It should not be switched. In addition it has to be fused close to the battery the battery. A 20A fuse is the norm and you can use 12g wire (14G is probably OK for short run or with a 15 amp fuse) The pump doesn't pull that many amps in normal operation ( maybe 5 or so for a small pump) but like any motor, there is an initial inrush current that is higher than running current and you don't want the fuse to pop when the pump starts. Also if the pump stalls due to debris or failure, it will pull a lot more current than normal and if no fuse, overheating or worse can occur.

If the boat is to have has a manual bilge pump option also, that connects to a circuit and switch at the helm . That circuit has a fuse or breaker and power is supplied from the battery switched accessories feed and bus. ( in other words, manual operation of the bilge pump only works when the battery switch is ON.

 

[seasick]

here are some pix from my V20. Its a single motor, single battery, no switch...
8 gauge feed to distribution panel under the dash.
Notice a 30Amp fuse on the battery for the feed to the panel.
Separate fuses for the bilge pump auto feeds.
A neg bus for any neg returns where it is shorter distance than running forward to the distribution panel.
The motor is connected directly to the battery, as is the house feed.

This setup ran two ff/gps, vhf, nav/anchor leds, cabin leds, cockpit leds, spreader leds, underwater leds, horn, 2 bilge pumps and a 12v accessory outlet.

]

In general wing nuts are not to be used for battery terminal connections. The proper connections for threaded terminal pots are machine nuts, not wing nuts

 

[IpswichGrady]

Regarding the bilge pumps, I have seen float-switches passing through fuse blocks (either at the helm or stern). They will not be ignition activated but live all the time. The manual on switch will go through my breaker switch panel. My intention was to feed them from my fuse block. I think that is how Grady did it originally. Small writing... straight from Grady

 

[SkunkBoat]

Can be done either way but you are adding a on/off switch to the House, I think.
In that case, you'll need to feed the float switches before the on/off switch.

 

[IpswichGrady]

Like this...

 

[DennisG01]

It appears your fuse block is NOT always on since it's after the battery switch. Unless you're coming off the hot post on the switch. However, the float switch is still not dedicated - if the 30a main breaker pops, the float switch will not work. I believe it was mentioned above, but the float switch should come DIRECTLY from the battery and it's own, inline fuse (may only be a 7.5amp or so, depending on bilge pump size), then to the bilge pump. After the float switch, on the way to the pump, you'll have a splice with a lead coming from your dash (manual) switch. The dash switch will have it's own feed from your fuse block, coming from the battery switch. When the battery switch is on, the pump can be activated via the dash switch or the float switch. When the battery switch is off, the dash switch will not work... which is a good thing as you won't accidentally leave it on.

It's also much simpler to go directly off the battery as you're keeping your wire runs shorter by coming directly off the battery. FYI, I believe the inline fuse needs to be mounted within X inches of the battery. Something like within 18" - but check into it as I'm not 100% sure on that distance. Just keep it close to the battery.

 

[SkunkBoat]

exactly what Dennis said. in your diagram the House battery switch will kill all power to the fuse block and so all power to the bilge pumps.

 

[IpswichGrady]

Ahh...see... this is why you ask questions. I guess I need to revisit my bilge pumps.... and even the whole schematic. Look into what others have done and fine tune everything.

question... I have a breaker protecting my whole house. Then after that up at the helm I have a fuse block and switches with breakers. Is the 30A breaker over redundant... unnecessary? or is it actually a good idea? or should I say just not a bad idea? I mean each circuit is protected individually either at the fuse block or switch w/breaker.

Let me make some changes to my schematic tomorrow and submit it for further review.

thanks

 

[DennisG01]

I think you're still missing the point of what breakers/fuses do. Here... answer this question and you shall have the answer to your question, as well -- What keeps the 8g wire from the battery to the fuse block from melting? :wink:

There's no need to try and re-invent the wheel or go scouring the internet and forums, "hoping" that what you find on a forum is correct. Just download a more recent (easier to read) owner's manual and look at how things are done and then copy that. I really think you're making this harder than it has to be... or at least creating more work for yourself.

 

[SkunkBoat]

don't be discouraged. Some of us have been working in electronics since 1978.
I too am going to rewire my boat and I'm dealing with 2 motors and 4 batteries. The way that Grady did it wasn't that great. It has 2 switches inside 2 different compartments that require removing bins to access the switches.There are a lot of options to consider and "play out"....

So..
The 50A breaker protects the heavy wire in case something crazy happens like you drop a wrench between your pos & neg bus or the sum of all your loads is too high for the wire to safely carry the current.
You are using the "AddaBattery" switch & ACR. Thats good. The switch has an OFF,ON,and CombineBatteries position. In the ON position the switch connects the Starting battery to the Motor and the House battery to the House load(thru the breaker). In the OFF position it disconnects both batteries from everything. Thats why you need to connect your Auto bilge pump circiuts directly to the House battery(thru fuses).
You can use the nearest Negative bus for the return of each pump.
( just a note...I may use Negative, Return, and Ground interchangeably and also Positive, Feed, and Source...)

Circuits should be fused very near to the +12V source. For instance, that 50A breaker should be connected between the House battery and the battery switch. The lead from the battery to the breaker ideally should be less than a foot. An exception to this has always been outboard motor starting wires. The circuit is fused 6 feet away, inside the motor (usually 60A). I don't know why that gets a pass but you never see a fuse or breaker at the battery for starting cables.

Some other things to know...
on a boat that only has DC circiuts, the Negative should always be black wire. On boats that also have AC (shore power) wiring, black wires are the hot wire in the AC circiut. DC negative wires are supposed to be Yellow but you can't ever trust that.
Bonding wire is another consideration. You should see green/yellow wire connecting the fuel fill and fuel tank to "Ground", i.e. the Negative battery terminal

 

[IpswichGrady]

Ok I get it now. As you can see I added a positive directly to the house battery. I found that I can attache it at the battery switch where the house lead attaches so it is not switched. Between the float switch and the battery there is a 7.5A fuse. The bilge is also attached to a breaker switch to activate it manually. And the negative is attached to the (-) bus bare in the stern.

Is it advised.. necessary to have a forward and rear? Boat came that way... I will keep it the same as factory and add another bilge the same way (forward)

 

[SkunkBoat]

that'll do.
you could move the main breaker between the battery and the switch to be more correct, but I've seen boats wired like that.

Boats over 20ft I would say definitely 2 bilge pumps. When in water, not moving, water tends to collect fwd on a deep V hull. A forward pump will remove rainwater at the dock. With a single aft pump, it only pumps when there is enough water in the bilge to reach the aft float. When you get underway, it all rushes aft and pumps out. Also, 2 pumps double your capacity if you get a big hole or get swamped by a big wave. And lastly, eventually something will clog a pump and it will blow a fuse, so you have a backup.

 

[DennisG01]

EDIT: Typing at the same time as you, Skunk... but you were faster!

Maybe I'm misunderstanding what you're saying, but: "I found that I can attache it at the battery switch where the house lead attaches so it is not switched"... means that your house lead is also not switched, and it should be. That's not to say that you can't attach the "full time power" for the bilge pump at the switch, as long as it's at the same spot where the house battery ties in. Or, maybe what you mean is... "Attach at the battery switch where the cable from the house battery attaches?

But, wouldn't it be simpler to just attach the bilge pump feed wire directly to the battery post?

Yes, definitely use the forward bilge pump. Any "bilge" should have a pump. I realize the forward bilge drains to the aft bilge, but if you get some water in the boat, and the boat is bow heavy (or pitching), that also means that the aft bilge will drain to the forward bilge.

Here's something to ponder: Add an "emergency" bilge pump in the aft bilge. This one wouldn't necessarily need to be wired to a switch - it could be wired ONLY to the battery with it's own float switch. Mount the pump on the bilge floor, but mount the float switch a few inches higher than the main float switch. If you would somehow get a huge amount of water in the bilge, and the level overcomes the main bilge, the emergency bilge will kick on to help. You don't see this too often in small boats, but it's pretty common in bigger boats where the manufacturer has put good thought into the design/build process.

 

[IpswichGrady]

"I found that I can attache it at the battery switch where the house lead attaches so it is not switched"

What i meant by that is I intend to put the un-switched bilge hot wire on the same bolt where the house battery connects to the battery switch. It will be before the switch and hence always on.

Huh.. I would think that the breaker would be better after the switch on the way to the house accessories because then if there is an overload the breaker would protect the switch and anything attached to it.

I will def do the dueling bilge pumps.

 

[SkunkBoat]

Huh.. I would think that the breaker would be better after the switch on the way to the house accessories because then if there is an overload the breaker would protect the switch and anything attached to it.

nope. nothing between a breaker or fuse and a power source is protected. That is why you want the breaker as close to the battery as possible with nothing but wire between them.
In practice, you will probably mount the breaker within inches of the switch, but it really should be on the battery side.

in you configuration, the hypothetical wrench between a nut on the House terminals of the switch and "ground" would be an unprotected short circuit.
That being said, the Starter side is also unprotected.

 

[IpswichGrady]

nope. nothing between a breaker or fuse and a power source is protected

I get what you are saying... the switch is not protected (or the ACR for that matter) because the breaker would be after it. And what you are saying is that if for some reason the switch should fail, unless the breaker was between the switch and the battery then there would be a meltdown.

in you configuration, the hypothetical wrench between a nut on the House terminals of the switch and "ground" would be an unprotected short circuit.
That being said, the Starter side is also unprotected.

Ok... So I get that the breaker should be In-line between the house battery and the switch to protect the house accessories and house battery. But are you also saying that technically there should be a breaker inline on the engine battery side? Mirror both sides? I get that... makes sense to protect the engine. But in my searches I can't recall ever seeing a breaker between the engine battery and the engine circuit. Uncommon? Unnecessary?

Ok here is a new question for you guys... I pulled up the trusty Blue Sea Circuit Wizard because you guys are turning me into a marine electrical expert. (http://circuitwizard.bluesea.com/). Why does a battery cable need to be so large going from the house battery to the switch if the distance is short... Or is it?
Educate me...

- I am protecting my system with a 30A breaker
- the distance from the battery (+) to the switch is say 3'
- the distance from the battery (-) to the (-) buss in the stern is also 3'
- if you input this info into the wizard the result is 12g wire. (12v - 6' - 30A - 3%)

I'm guessing my distances must be the issue.

 

[DennisG01]

The engine will have it's own breaker/fuse to protect itself.

The cable from the house battery to the switch needs to be large because it's possible to use the house battery, if needed, to start the engine. There's a possibility of having a large draw on that house cable, so it needs to be sized appropriately.

 

[SkunkBoat]

I fear I may have confused things by trying to convey the ideal circiut protection and hypotheticals.
I was trying to get you to think about why you are connecting things in certain ways.
In general, the fuse should be as close to the power source as possible because you are trying to protect the wire.
In practice, nobody fuses the feed to an outboard. The motor is protected by an internal fuse but the wire to the motor is not.
ABYC standards actually make an exception for outboard motors.

Dennis has made a great point that I did not consider. There is the possibility of putting the switch into the COMBINE position to try and start the motor from both batteries.
For this reason, it would not be correct to put the 30A breaker between the battery and the switch. Starting the motor would almost certainly pop that breaker.