House battery is the same as the generator starting battery?

Gimme Time

Gimme Time

Active Member
GOLD Sponsor
Jan 7, 2007
907
Charlottesville, VA./ Deltaville, VA. / Tidewater
Boat Info
2006 52SB, Ray Marine E120, Garmin 7612 through BOE site sponsor,
Engines
QSM11s
Ok, so everyone reading will be on the same starting point. The 52DB like many other SR boats is configured with (2) 12 volt group 31 batteries for the bow thruster which has no problems nor conflict or concerns. There is no dedicated stand alone generator battery.

The two Cumminis QSM11s each have a 12 volt Group 8D batteries if I recall correctly. My Port engine battery is also the house battery as well starting back for the Port engine. The Starboard engine is on its own group 31 battery.

What I’d like explain to me is the logic of having the house battery also serve as the generator starting battery, the Port engine starting battery and the house battery.

This leaves you in a condition that when the house battery fails as mine did then you lose the generator starting battery as well as the house battery. Wouldn’t it make more since to have the generator starting battery on a dedicated battery of its own Ot on the Starboard battery which only does the Starboard engine?

I must be missing something here? Please feel free to explain when you can?
 
I am setup with a starting battery dedicated to the generator. Not sure why you would not be the same. Then I have two group 27 in parallel for each engine that are both starting and house
 
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No genny battery here as well. Bank of 3 on stbd side and bank of 2 on port. The electronics and accessories are split up between the 2 different banks. Bow Thruster runs off the Port. Not sure if this was a SR thing or something the PO did. Seems to be setup kinda strange. I would have thought the house batt would be independent. That is how my Maxum was set up. Although - this has worked well so far as having plenty of power to be on the hook for 10+ hours several times though out the summer and no issues starting either motor or genny.
 
Gimme Time said:
The two Cumminis QSM11s each have a 12 volt Group 8D batteries if I recall correctly. My Port engine battery is also the house battery as well starting back for the Port engine. The Starboard engine is on its own group 31 battery.
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There should be two 8D batteries if same as originally equipped and not a Group 31 in the mix. Each battery has switched and un-switched loads from the Main Disconnect Enclosure (MDE) as well as engine and generator starting. There are circuit breakers in the MDE as well as the DC Distribution panel and the house circuit breaker panel. All of the loads on the house circuit breaker panel are with the port battery. In the 52DB there are no circuits that share both batteries nor are there any isolators or ACR's; the only device that connects the two 8D batteries together is the Emergency Start Solenoid (located in the MDE) which is engaged only when the Emergency Start switch on the helm is depressed. You are correct that the House Loads and generator starting and port engine starting are all on the Port battery. This is not a good arrangement should you need to get the generator started using the starboard battery so the battery charger can operate. The intent should the house draw the Port battery below it's capability to start either the port engine or generator is the Starboard engine can start then with the Emergency Start button start the port engine and allow the engines' alternators charge the batteries. This is a design which has many single point failure possibilities which could render the boat inoperative should the captain not pay attention to the state of charge on the batteries. This basic weakness in the electrical system is one the reasons that, in our case, the generator is running when we leave the dock and does not shut down until we are reconnected to shore power; of course Air Conditioning is really the primary reason for the generator running. I am getting ready (engineering is just about complete) for a major electrical system refit on my boat in which many of these short-comings will be corrected.
 
I have 4 group 31's My port bank is the house and starts the engine and generator. If it gets drawn down I get an alarm from my Victron battery monitor. I can use the emergency start to crank the generator and run the charger. This has always worked well for me. I also remove the fuse from the generator charging circuit so it doesn't interfere with my smart charger. SR puts some circuits on the starboard bank that should be on the house imo. Its a bit puzzling to figure out. I have never been left stranded on the hook though. My house bank easily lasts all day and even overnight if you are stingy with loads.
 
I am working on a solution for this problem on my 52DB and figured out my plan this past weekend. I am going to separate out the generator to it’s own dedicated starting battery. In the MDE the shut off solenoid draws its power from a port battery connection. My intent is to remove the feed from the port battery and run a new battery cable from the new group 24 starting battery I am going to add. I think I have enough room between the existing batteries and the exhaust muffler to fit a group 24. There are empty connection lugs on the bottom of the MDE so I will utilize one of those to connect the new battery to the generator shut off solenoid. Once I do this the generator will be on its own isolated start battery and the stock generator battery shut of switch in the DC panel will still operate that circuit.
 
Mine has a dedicated generator battery located behind the house batteries I figured they where all set up like this.
 
2808670-R1-015-6.jpg
Dedicated battery for the genny here.
 
Jeremygavin said:
I am working on a solution for this problem on my 52DB and figured out my plan this past weekend. I am going to separate out the generator to it’s own dedicated starting battery. In the MDE the shut off solenoid draws its power from a port battery connection. My intent is to remove the feed from the port battery and run a new battery cable from the new group 24 starting battery I am going to add. I think I have enough room between the existing batteries and the exhaust muffler to fit a group 24. There are empty connection lugs on the bottom of the MDE so I will utilize one of those to connect the new battery to the generator shut off solenoid. Once I do this the generator will be on its own isolated start battery and the stock generator battery shut of switch in the DC panel will still operate that circuit.
Click to expand...
This is probably the best fix; and, I would add an ACR between the Port battery Solenoid and Generator Solenoid (battery sides) inside of the MDE if you can find the space. Lastly I believe our battery charger in the 500DB/52DB are 3 bank which one bank is not used; that spare charging circuit should be routed through a new circuit breaker in the Main Circuit breaker panel (note that the two existing bottom circuit breakers are the battery charger breakers for port and starboard batteries) then to the battery side of the generator's solenoid. Now you would have redundancy in alternators, battery chargers, and batteries.
 
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ttmott said:
This is probably the best fix; and, I would add an ACR between the Port battery Solenoid and Generator Solenoid (battery sides) inside of the MDE if you can find the space. Lastly I believe our battery charger in the 500DB/52DB are 3 bank which one bank is not used; that spare charging circuit should be routed through a new circuit breaker in the Main Circuit breaker panel (note that the two existing bottom circuit breakers are the battery charger breakers) then to the battery side of the generator's solenoid. Now you would have redundancy in alternators, battery chargers, and batteries.
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Thanks for the insight on the battery charger. I hadn’t gotten that far this past weekend so it is good to know. Can you explain the ACR between the port battery and generator Battery? I was going to disconnect them entirely in order to separate the systems.
 
Jeremygavin said:
Thanks for the insight on the battery charger. I hadn’t gotten that far this past weekend so it is good to know. Can you explain the ACR between the port battery and generator Battery? I was going to disconnect them entirely in order to separate the systems.
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Sure - the ACR will provide an alternant means to charge the generator's battery from the port engine's alternator; redundancy. Should the generator's alternator fail then the generator's battery can be charged from the port engine's alternator. The ACR looks at differential voltage and determines the need for charging.
 
ttmott said:
Sure - the ACR will provide an alternant means to charge the generator's battery from the port engine's alternator; redundancy. Should the generator's alternator fail then the generator's battery can be charged from the port engine's alternator. The ACR looks at differential voltage and determines the need for charging.
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Thanks for the explanation, I will check it out.
 
John,
Just a thought. In the meantime, should the generator battery fail again, I would think as an emergency start for the genny, you can have someone press the emergency crossover switch located between the start/stop switches on the bridge while you try and start the genny. Not sure if that would work or not. That may only allow the port engine to start from the starboard battery and as previously mentioned, you would need to allow the alternator to charge the port battery. As I think about it, probably would not work but would in fact be a nice feature. Even with a separate battery for the genny, it would be nice to be able to use the main 8D batteries as a back up for the genny.
 
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Quick easy emergency plan that works and is pretty cheap. Good Heavy duty gauge copper jumper cables will get you home to the best of my knowledge and there on board GT now. Sometimes if you’re prepared you never need them
 
Gimme Time said:
Quick easy emergency plan that works and is pretty cheap. Good Heavy copper jumper cables will get you home tp the best of my knowledge and there on board GT now. Sometimes if you’re prepared you never need them
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I have jumper cables on board... Never had to use them worth every penny
 
Blueone said:
I am setup with a starting battery dedicated to the generator. Not sure why you would not be the same. Then I have two group 27 in parallel for each engine that are both starting and house
Click to expand...

That’s what I have.
 
I like the idea of jumper cables on the boat.
I keep a good set of heavy copper (not CCA) jumper cables in every car, another in my garage, and now I’m going to stash a set on the boat too.
You guys have me thinking that along with jumper cables it might be a good idea to keep a jump pack on board. I’ve got one in the garage at home that would take up too much space, but they make the smaller brick style ones these days that would be easier to store.
I’ve often got smaller boats rafted up to me and it would come in handy if one of them had a problem.
 
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