House Batteries

W

Wizard

Member
Oct 10, 2006
49
Long Island Sound
Boat Info
380 Sundancer 2000
Engines
454 mercruiser with v drives
I have a '00 380 da. The boat came with 5 batteries which were all group 27 deep cycle (wet cell). I replaced them all three years ago. It is time again to replace and the battery guy says do you have house batteries? I never thought about it until now. I now assume that there would be 3 starting batteries, one for each engine and one for the generator. I also am going to assume that these 3 would be deep cycle. That leaves 2 batteries for the house which the battery guy says are a little different because they have thicker plates. Do you guys use all deep cycle or should I be looking for different ones for the house? Thanks.
 
I have Marine Deep Cycle batteries for house batteries. I have wondered also whether or not they need to be deep cycle due to the fact that they aren't ever hit with starting loads and are under charge any time I am hooked to shore power or am running the generator.

I have noticed that if I inadvertantly leave a light on for an extended period that they will run down even with the inverter and charger connected. Maybe because they are deep cycle.

You ask a good question.
 
Wiz,
WE dont have " House " batteries" like in the old days. Today we have our engine battereies and house batteries all together. I think its a stupid idea. Anyway so u dont have DEDICATED house batteries. Ur port Batteries start ur port motor and maybe ur genset plus house duty and stb side batteries start ur stb motor maybe ur genset and house duty. So yes U can kill all ur battereies. Would take work but is possible. BAD DESIGN. But if u have a bow thruster Those battereies are isolated and would still have a charge . So Deep cycle for all would be the way to go.


Rob
 
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The 380DA has the aft two batteries for the starboard bank, the forward two for the port bank and the inboard battery dedicated to the generator.

The tray and the clamps holding the group 27 will accept a group 31 without changes.

Mine was modified to have six group 31 batteries, for longer on-hook time. I also have a switch to short both banks together, when required.

The gen / charger is the back-up.

CharlesCharger.jpg
 
I think mine must be hooked up different because I have drained the house on the hook (lights, fridge, CO)and still had plenty of juice for starting both engines. I would like to better understand my setup because I would like to add another battery to the house.
 
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Dave, Samething happened to me on the hook last year and that was after using the generator to keep the batteries up. When I pulled anchor that day my Plotter would not "fix" for a short while and later thinking about it, I'm wondering if the batteries needed to be charged up while running at cruise?
 
Check you main battery switches. Usually you only use the Port Bat bank for starting and the STB Bank for house
 
Asureyez said:
Check you main battery switches. Usually you only use the Port Bat bank for starting and the STB Bank for house
Click to expand...
My setup is the other way around. The port battery bank starts the port engine AND runs most of the house DC needs. The starboard bank only starts the starboard engine (OK, it also powers the electronics on the bridge).

I guess the theory is if the port bank goes dead you can always start the starboard engine or use the "emergency start" (which parallels the two banks) to start the port engine. I also have two 12V batteries connected in series to generate 24V for the bow thruster. I use this bank to power a 24V inverter.

I don't like this setup. I would prefer a dedicated house bank separate from the starting batteries. I guess it was done this way to save $pace. When I replace the port batteries, I will consider replacing them with a pair of big ol' 8Ds.
 
Wiz,

Rob's assessment is correct. You have 2 batteries for each engine, and they also serve as banks for the house DC circuits. The 5th battery is for the generator, and is your backup in case the other 4 go down. If you buy good group 27 batteries, and keep them topped off every 30 days with distilled water, they could easily go 4-5 years. I've had them last as long as 6 years, but with less maintenance, you will get 2-3. If a battery every goes completely down, its life gets shortened by 1/3.....it's just never the same again.

Never attempt a copyrighted cool mod, like installing a 120 volt outlet in a gas engine room.
 
We have had ALL deep cycles for the past 5 years without any problems. I just replaced them again with deep cycle Deka 31's. Hope to get 5yrs outta these with proper maintenance. I too often wondered how they were wired. I believe that the thought of two for each engine and the house running off one of the pair is correct.
 
Rob is correct on how the batteries are set up. On the Searay website you can download the parts manual for your boat. It includes a detailed battery electrical diagram that shows what each set of batteries power. It also has the battery size recommended by Searay.
 
General rule is you can start with a deep cycle battery, but don't deep cycle a starting battery.

A deep cycle is made to be discharged and re-charged. You won't hurt them by discharging unless you go too low. You also won't hurt them by starting an engine with them, they just won't produce as much cranking amps as a starting battery. Think golf carts.

A starting battery is all about cranking amps to start your engines. This is important with diesels, big block gassers and in the cold. You will wear out starting batteries in a hurry by discharging them too much or too often. Think car battery.

On most modern Searays, the same batteries start the engines and run the house loads. IMO they should always be deep cycles. If the deep cycles won't give enough amps to crank your engine, use more batteries.
 
tdappleman said:
uh... is that an electrical outlet I see in a gas engine room...?
Click to expand...

Don't worry the set-up is copyrighted (well papers are not actually filed but it is nonetheless because it is), no one else can use that set-up in their engine room. :thumbsup:
 
Since there all BANKS deep cycle is the ony way to go. I'm in the process of swapping to AGMS . Someone posted about Sears Platinum Batteries. At first I laughed and then then I did a comparison and there pretty damn good. More cold cranking amps then the optima. LONGER RESERVE and BETTER WARRTY....

Rob
 
First Born said:
Don't worry the set-up is copyrighted (well papers are not actually filed but it is nonetheless because it is), no one else can use that set-up in their engine room.
Click to expand...
Nice trolling monkey boy.
Robski97 said:
Since there all BANKS deep cycle is the ony way to go. I'm in the process of swapping to AGMS . Someone posted about Sears Platinum Batteries. At first I laughed and then then I did a comparison and there pretty damn good. More cold cranking amps then the optima. LONGER RESERVE and BETTER WARRTY....
Click to expand...
When I've compared battery options I include specified cycle life, ampere-hours and cost, to arrive at lifetime delivered ampere-hours per dollar.
 
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