How to connect house feed to new Blue Sea Add a Battery Switch

S

Slrademacher

New Member
Jul 11, 2007
19
Wisconsin
Boat Info
2000 240 Sundeck
Engines
5.7L Mercruiser w/Bravo III
I’m looking to install a Blue Sea Add a Battery kit on my 2000 240 Sundeck to separate the starting circuit from the house circuit and provide charging to both. The start side is fairly straight forward. I’m a little fuzzy on the house side – specifically the best way to connect the house feed to the switch. I can’t get to the boat yet (it’s in a drystack and the marina doesn’t open till next week) so I’m relying on the wiring diagram and some quick photos I took inside the engine compartment at the end of last season. I'd like to have as much figured out beforehand. I’m replacing a basic factory installed on/off battery switch. From the diagram, it looks like the house feed connects at the starter (through a 50 amp fuse) to get positive. What’s the best way to connect that wire feed to the switch? Do I just route an appropriate sized and fused wire from the switch to the starter and connect that end to the house feed wire I disconnected from the starter?
 
Let's see if I can help. I installed the same system you're contemplating about two years ago. I'm on the road right now so pictures and memory is all I have to go on. I separated the electrical system as follows: The Start Battery has the starter, ignition, Mercathode, trim pump, stereo memory and the aft 12 volt accessory circuits . The House Battery has everything else- lights, stereo, amp, chart plotter, water pumps (wash down and heater), etc. The idea was; What happens if I leave a light on or we have a big party and I drain the house battery with the stereo and amp? The way it's configured now, I simply turn the key and the engine starts and both batteries start to charge.
My fuse box is up underneath the helm and I separated the ignition circuit out from the rest of the circuits and ran it's own 12 ga wire back to the Start battery. In the engine compartment, next to the started solenoid, I broke open the main wiring harness and found the 8ga wire that supplies the fuse box underneath the helm. I cut the wire (thereby separating it from the start battery) and spliced in a section of wire back to the house side Blue Sea switch. The rest of all the house items that were aftermarket and thus not connected to the fusebox each have their own inline fuse and are attached to a binding post next to the Blue Sea switch (not pictured). The aft 12 volt accessory port was added by me and is located topside next to the companionway directly behind the aft bench seat. It is hot-wired to the start battery and serves two functions, one is to use as a power port for inflating water toys and two, to be used as a charging port for the boat's batteries. I plug in a Battery Tender trickle charger into this port during the winter months and it will top up the start battery first, then when the voltage gets high enough, the Blue Sea relay will close and auto parallel the batteries and charge the house battery. It has been flawless in it's operation and I never worry about running out of juice or switching batteries. It's all automatic. BTW, my house battery is a group 27 from Walmart. I think I paid $90 for it. I have tried to run it down with the stereo blaring but so far, no luck! :)
http://


http://


To orient you, this is the port side of the boat underneath the wrap around lounge seat looking towards the engine compartment and aft. The trim pump is just visible bottom photo. The battery switch is located on the port wall of the engine compartment and is accessed by opening up the engine hatch. The house battery is in the foreground. The box in the middle is the auto relay. It's looking at the relative voltages of the two batteries. If one falls below a certain amount, the relay opens and separates the batteries. When a charging voltage is applied (in this case to the start battery), the relay senses the increase in voltage and will close the relay allowing both batteries to take a charge. The binding post towards the aft is a common ground. And the back side of the switch is in the foreground.
 
Last edited:
Thanks for all of the information and pics. I'm surprised how involved this is. Blue Seas documentation makes it seem like you just switch a couple of wires and your done. I had read other posts that are similar to your experience, although not as directly answering my question. I got to my boat yesterday and installed the new battery tray and the switch and acr in the battery area. My old On/Off Guest Switch had the battery + on one post, and the + to the motor and another large red wire on the other post. I was able to identify the other expected + leads (bilge pump, trim pump, stereo memory, stereo amp) directly connected to the battery + post. I wasn't sure what the largish wire fed. I hoped it was a house feed that somehow was not shown in the official Sea Ray diagram but I don't think it is. You can see it as the third smaller wire in this picture:
IMG_9716 (Medium).JPG
Do you recall, was the wire you split out from the main harness a red wire with a purple stripe? I assume your radio still requires the key be in accessory to work but that everything else on the house battery works the way they did before you split the wire out?
 
Fist of all, I should have warned you about one of my many flaws. That is over-engineer stuff to death! My setup was born out of the necessity of having a very high amp sound system that would run the start battery down pretty quickly if I really cranked it up. Anyway, yes you can literally just "Add a Battery" and not rewire your whole electrical system. And really, you'd achieve the same result. The difference would be is that you'd really only have the second battery "auto charged" and if you ever ran the first (start) battery down, you'd have to manually select "COMBINE BATTERIES" on the selector switch to get the boat running. As far as your largeish red wire, yes, the wire that feeds the fuse panel is around 6 ga and has a purple stripe. You could test this by disconnecting the wire from your switch and verifying that you've lost power to the fuse panel.
You are correct about the radio and the other accessories needing the key to be on to use and works the same way as before.
 
I figured out that the largish red wire is the positive for the trim pump. I didn't expect it to be so beefy, but I followed it back to the pump.
So if I understand your setup correctly, you ran a new 12 gauge wire from the start battery (i'm guessing actually the "on" side connection for the start battery on the switch) to the fusebox, wired directly to positive supply of the ignition (replacing the red/purple positive supplied by the existing 8 gauge at the fusebox)?
 
That would be easier to wire, but it wouldn't accomplish what I want to do, which is have a dedicated start battery and a dedicated house battery and only have to turn the switch between Off and On.
 
Slrademacher said:
That would be easier to wire, but it wouldn't accomplish what I want to do, which is have a dedicated start battery and a dedicated house battery and only have to turn the switch between Off and On.
Click to expand...

Understand. My Regal came prewired as I described above. On odd day dates I used the #1 Battery for starting and #2 while on the hook. On even day dates I used the #2 Battery for starting and #1 while on the hook. I switched to both (after starting) for the cruise out and home.

My logic, possibly flawed, was it evened out the wear and tear.

Good luck with your project. Post pix.
 
Slrademacher said:
I figured out that the largish red wire is the positive for the trim pump. I didn't expect it to be so beefy, but I followed it back to the pump.
So if I understand your setup correctly, you ran a new 12 gauge wire from the start battery (i'm guessing actually the "on" side connection for the start battery on the switch) to the fusebox, wired directly to positive supply of the ignition (replacing the red/purple positive supplied by the existing 8 gauge at the fusebox)?
Click to expand...

Correct. 12 ga is fine for just that one circuit. It is fused BTW.
 
You must log in or register to reply here.

Forum statistics

Threads
113,259
Messages
1,429,520
Members
61,136
Latest member
Gforce lll
Back
Top