Battery Switch 1/2/Both with Twins

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plumsal

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I have twin f150s with two Guest 1/2/Both/Off switches. Radar, VHF, stereo, MFD, baitwell. Have two Deka 27m6 cranking batteries (technically they are dual purpose).

Anyway, I usually just keep port battery switch on #1 and the starboard switch to #2. I can see the voltages going up to +/-14.4V or so with the engines on, so I assume each engine alternator is separately charging each battery. So if I drain a battery, I can always go to the other. Switching to “Both” would be for emergency only.

Is my thinking correct or am I missing something?

(and I plan later to add a third dedicated house battery with a VSR switch)
 

pelagic2530

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You are probably correct in your thinking. Only way to know for sure is to unscrew the switches from the transom, and see how they’re hooked up. Not a bad idea anyway, if just to check the state of your battery connections.

Your best bet for adding an additional battery is to replace your current switch setup with a BEP cluster switch. That way, each engine will charge its own cranking battery, and both will charge the house battery through independent VSRs. Nice clean install, and very simple user interface.
 

warthog5

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BEP for twins.
 

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pelagic2530

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BEP for twins.

@warthog5, I’ve seen something interesting on a FB page I follow, wanted to know your thoughts. There’s a guy who does a lot of high end boat rigging, usually with BEP switches. Looks like he’s adding an additional emergency parallel switch to the cluster. By the looks of it (he won’t answer my question about how exactly it’s rigged 🙄) it places the house battery in parallel with one of the start batteries via a cable running to both of them (I suspect the switch is just a normal on/off switch with an “emergency parallel” knob fitted onto it). In theory, it would allow you to parallel the house battery to one or
both of the start batteries, either in case of a prolonged emergency or a failure of some sort in the house battery. Ever seen or installed something like that?
 

plumsal

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Guys, that BEP install looks great! But I am a complete newbie on stuff like this.

Any recommended books/resources for an electrical novice to undertake something like this? What would be the typical install price if I paid for it?
 

pelagic2530

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Guys, that BEP install looks great! But I am a complete newbie on stuff like this.

Any recommended books/resources for an electrical novice to undertake something like this? What would be the typical install price if I paid for it?

Replacing the battery switch with a BEP cluster is actually a pretty simple upgrade. Your input and output wires will stay the same, and more than likely you won’t need to replace any cables. The only new connection will be two negative wires, one from each VSR, which get spliced into one wire leading to the negative bus at the stern, or a battery negative terminal if a bus isn’t installed.

Regarding resources, combing through electrical upgrade threads on this forum is a great place to start. To get some basic 12v knowledge, there are lots of YouTube videos, and books available on Amazon, that will point you in the right direction. Nigel Calder and Ed Sherman are two outstanding authors on the subject.

Labor rates and parts cost will vary greatly depending on your location and what exactly needs to be accomplished. Provided it’s a simple switch swap, with good access and no cables that need to be replaced, you’re likely looking at a few hours of labor plus parts. It gets much more complicated if there are other issues in the system. If you list your location, you might get more accurate numbers.
 
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Efx

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I have twin f150s with two Guest 1/2/Both/Off switches. Radar, VHF, stereo, MFD, baitwell. Have two Deka 27m6 cranking batteries (technically they are dual purpose).

Anyway, I usually just keep port battery switch on #1 and the starboard switch to #2. I can see the voltages going up to +/-14.4V or so with the engines on, so I assume each engine alternator is separately charging each battery. So if I drain a battery, I can always go to the other. Switching to “Both” would be for emergency only.

Is my thinking correct or am I missing something?

(and I plan later to add a third dedicated house battery with a VSR switch)
You have an aux output on your engines which can charge a separate house bank.
 

warthog5

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@warthog5, I’ve seen something interesting on a FB page I follow, wanted to know your thoughts. There’s a guy who does a lot of high end boat rigging, usually with BEP switches. Looks like he’s adding an additional emergency parallel switch to the cluster. By the looks of it (he won’t answer my question about how exactly it’s rigged 🙄) it places the house battery in parallel with one of the start batteries via a cable running to both of them (I suspect the switch is just a normal on/off switch with an “emergency parallel” knob fitted onto it). In theory, it would allow you to parallel the house battery to one or
both of the start batteries, either in case of a prolonged emergency or a failure of some sort in the house battery. Ever seen or installed something like that?

I'm not sure.....BUT....The Yellow / Combine switch does exactly that and it's part of the BEP cluster.
 

warthog5

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I did a twin not to long ago.
Guy is working on the boat himself, but wanted me to install the BEP cluster. I also ran 6ga to feed a fuse panel and what ever he wanted to throw at it.? It had Power Posts @ the transom to make the engine hookups.

Batteries were not included....But I am attimate on the Battery trays that I use.

The parts $1150.87 and Labor was $1032.25 I usually say $2500 off the cuff.
 

pelagic2530

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I'm not sure.....BUT....The Yellow / Combine switch does exactly that and it's part of the BEP cluster.
Yeah, I’m familiar with the one that’s installed as part of the normal cluster.

This guy appears to be installing another one to parallel in the house battery: D7B6AD1F-3D9B-4F4D-96D1-39227AAFCC6F.png
(Not my photo; screenshot from a FB group.)

Looks like it’s just a standard BEP mini on/off switch with the knob replaced; connects the house and stbd start battery in parallel through the switch.

@plumsal, sorry for the hijack. Happy to help with any other info you need.
 

warthog5

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Good pix...Clean work.....No idea as to why he did that, as the Top combine parallel's House to Both Start batteries.
 

pelagic2530

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Good pix...Clean work.....No idea as to why he did that, as the Top combine parallel's House to Both Start batteries.
Wart, you sure about that? Looking at the back of the switch, it looks like that parallels the two start batteries via the busbars. I can’t see any way that the house battery gets looped in.

Here’s a picture of the back of my switch, start batt switches on the right with the parallel switch in between:E33E3B9A-E6AB-4834-A719-E8CC7FFE5B41.jpeg

With the house switch and the VSRs on the left, I don’t see any way that the house battery gets paralleled into the system via the installed switch.
 

warthog5

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My mistake.....It is that way on the "single " BEP's. As you can see.....It combines the 2 "Start" batteries.

You did change those 10ga wires out....Correct? Every one I do.....It gets done to get Rid of those stupid Yellow ends that are open.....Use Crimp/ Shrink ends.
 

chas650r

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You have an aux output on your engines which can charge a separate house bank.
Agreed..........When this is available it is the best and simplest solution by far. All the auto switching is already included.
 
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pelagic2530

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My mistake.....It is that way on the "single " BEP's. As you can see.....It combines the 2 "Start" batteries.

You did change those 10ga wires out....Correct? Every one I do.....It gets done to get Rid of those stupid Yellow ends that are open.....Use Crimp/ Shrink ends.

Sure did. That’s the “before” picture so I remembered how to put everything back 😂

I’m playing around with the idea of installing a 1-2-both-off switch in that same position, with a house battery cable to the COMM port and cables running from the 1 and 2 lugs to the port and stbd sides of the existing parallel switch, as shown:1B5456C9-EB48-4AD0-A970-9B3CA9B0745A.jpeg
That should allow me to parallel the house with either the port start, stbd start, or both, should the situation require it.
 

plumsal

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Agreed..........When this is available it is the best and simplest solution by far. All the auto switching is already included.

Ok, so I can skip the ACR/BEP complication because I basically have a built-in ACR on each engine, right? Since I have twins, do I run the aux cable from EACH engine to a single HOUSE battery? What kind/how big should that house battery be (have two Deka 27 wet cell starting batts now). Trying to think this through correctly….
 

warthog5

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"Usually" a single Gp27 Deep Cycle is all that is needed.

Unless you put a Amp for sound system in.
 

pelagic2530

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Ok, so I can skip the ACR/BEP complication because I basically have a built-in ACR on each engine, right? Since I have twins, do I run the aux cable from EACH engine to a single HOUSE battery? What kind/how big should that house battery be (have two Deka 27 wet cell starting batts now). Trying to think this through correctly….

If you’re going to run the two-battery setup that came with the boat, this will work (sort of). If you are in fact equipped with an aux charge lead off each engine (check on this; often times twin engine installations are not) then cross connecting them will allow each engine to charge both batteries. You still won’t have a “house” battery since your starting circuit is not separated from your house circuit with the switch configuration you have in place.

If you’re going to add another battery as a dedicated house battery, upgrade your switch to the BEP cluster. Trust me, it’s worth it.
 
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