Mainship house batteries

We’re new owners of 2006 #34_Trawler_single_diesel.
Our boat uses house batteries to start the main engine. Is this common on all 2006 Mainship single diesel 34 Trawlers?

Congrats on your new boat. We will need some photos please. Yes that appears to be how Mainship did the batteries. Is it the best way, IMO no it isn’t. I want a start battery for each engine and a dedicated house bank. Will it work like yours is wired, yes until you run the batteries down overnight and then can’t start the engine.

Yes that is common and Commodave is correct that it is not the best way. So dont let your battery's get too low (speaking from experience). The way it is wired is a pain plus add in a 5th battery for the aft fridge and it makes a nice puzzle.

Personally I would not want to leave my boat wired that way, especially for the reasons that Dave mentioned. Also, "dual purpose" batteries (ones that are supposed to be good for both house (deep cycle) and starting) make poor house banks. It is best to have true deep cycle (like golf carts) batteries for your house bank.

Yes, that is how they were wired. While not "ideal" I never found it to be a problem.

I just left the battery switch on BOTH and made sure they got charged (via the engine or battery charger) every 1-2 days.

Your generator should have a separate, isolated start battery.

macp said:

We’re new owners of 2006 #34_Trawler_single_diesel.
Our boat uses house batteries to start the main engine. Is this common on all 2006 Mainship single diesel 34 Trawlers?

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Yes very common. MS used house / start battys on many years / models. I didn't like it for several reasons and recently moved my single engine start to my dedicated thruster bank. If you have a thruster batty / bank on port side its relatively convenient to wire the starter to it and its about half the distance as the stbd side bank. My house bank is now strictly house. Gen has a separate start batty.
My Bacchus website has a good summary of previous project to eliminate diode isolators MS installed for alt & shore charger that I eliminated to improve charging.

It's a very common set-up on many brands of (especially) powerboats. Mostly seems to work well enough, especially if the operator pays at least a nano-second's worth of attention to the batteries every so often.

-Chris

Dave, who runs their batteries down overnight? No one I have ever heard of. If it is done, it is done by a fool.

Comodave said:

Congrats on your new boat. We will need some photos please. Yes that appears to be how Mainship did the batteries. Is it the best way, IMO no it isn’t. I want a start battery for each engine and a dedicated house bank. Will it work like yours is wired, yes until you run the batteries down overnight and then can’t start the engine.

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Actually I never have since I always keep a separate starting battery. But I have towed in dozens who did run the batteries down and could not get started. And most could not even call on the VHF since it was powered by the same batteries. They had to wait and wave someone down who could call for help.

It depends. Many prefer the separation of house & start batteries. On the other hand if you go over to the sister “cruisersForum” , u may find that most cruisers opt for 1 large bank of high AHr batteries serving both functions. If u have a generator with it’s own start battery (or better still, a generator with it’s own start batteries and jumper cables) there is no reason not to maximize your combined start/house bank.
In future consider reducing house loads, (LED’s etc.) add decent battery monitoring/coulomb counters & solar depending on your budget.

There sure is an argument to have just the house batteries that do the start also. And a generator battery that could start the gen OR engine. With that set up you'd most likely get the best use of batteries.


Also, you could have a separate thruster battery that could back up the start also.


You really don't need a separate start battery, especially one for each engine. I have that with my new boat and feel it's a waste and gonna rework things.

I agree that many will disagree re what is the "best" batty bank arrangement. Sort of akin to the best anchor discussions.
Everyone should evaluate the +/- of the various arrangements and how they fit their style of cruising and tolerance for any upsets.
There is no tight or wrong way for all.
I'm happy to detail my choices and reasons why if anyone is interested. I havent posted my latest elec mods on my website but plan to as time permits.
Having a good monitoring system has added an increased level of info, understanding and confidence with my banks.

Our 2007 Mainship 430 has two 200ah house banks, each of which also starts one of the twin engines. It's not preffered to me, but I live with it. I do have a separate starter battery for the generator. To add starters for the engines, I would need 4 more batteries because we have a 24v set-up. And I would need to set-up charging for the additional 2 starter banks... It just hasn't made it to the project list.

Mark Rinkel
ourpositivelatitude.com

Curious. If the gen has a dedicated battery but engines share the house battery, why not share the gen battery with the engines instead.

Soo-Valley said:

Curious. If the gen has a dedicated battery but engines share the house battery, why not share the gen battery with the engines instead.

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It`s better not to share the genset batt with anything. It`s back up to start the genset to recharge the main batts to get going when something has gone wrong.

I agree with BruceK about keeping the generator starter batteries (2 12v in series) dedicated to the task. It has bailed me out twice in the past when the house battery bank dropped too low. I've replaced the house batteries since then and have better battery management so it's not as much of an issue now... but it is a very good back-up.

Sums it all up nicely. No need to worry IF one happens to run down a larger battery bank because there are quite viable backup alternatives. But, aren't most, if not all of us, religious about making sure we do not deplete below 50% depth of discharge anyway?

Flatswing said:

It depends. Many prefer the separation of house & start batteries. On the other hand if you go over to the sister “cruisersForum” , u may find that most cruisers opt for 1 large bank of high AHr batteries serving both functions. If u have a generator with it’s own start battery (or better still, a generator with it’s own start batteries and jumper cables) there is no reason not to maximize your combined start/house bank.
In future consider reducing house loads, (LED’s etc.) add decent battery monitoring/coulomb counters & solar depending on your budget.

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I have house batteries (4-6volt to make 12v), a single D8 to start motor and another battery for the generator. While sleeping over night with the lights and fan on it runs the battery down, I had to jump it this morning. I also found that my alternator is not working either..(currently have jumper cables running to the D8 until I reach KW). I can not run my DC Panel off the house batteries, only the D8. Is this common? I would much rather run off the house batteries and sleep better knowing the D8 is fine.

Sykes said:

I have house batteries (4-6volt to make 12v), a single D8 to start motor and another battery for the generator. While sleeping over night with the lights and fan on it runs the battery down, I had to jump it this morning. I also found that my alternator is not working either..(currently have jumper cables running to the D8 until I reach KW). I can not run my DC Panel off the house batteries, only the D8. Is this common? I would much rather run off the house batteries and sleep better knowing the D8 is fine.

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It would help if you include boat make, model, year in your profile so we have better info.
I'm confused by your statement that your DC panel is not connected to the house battys?
Usually the 8D start batty is connected directly to starter and NOT to/ through the DC panel so what you describe sounds backwards?

Sykes said:

I can not run my DC Panel off the house batteries, only the D8.

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If you can not do this, what are the house batteries used for?

Xlantic said:

If you can not do this, what are the house batteries used for?

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DC panel feeds radio, sounder, instruments that are needed underway. House batteries feed inverter and lights while at anchor. So house does not need to feed DC panel unless you want it to.

I chose to simplify my last boat's starting battery set-up by using a pair of 530 AH
6-volts for all 12 VDC needs. The house and thruster were supplied by 4 of the same
530 AH batts for 24 VDC. So I guess you could say I had separate starting and house
batteries even though the generator and engine shared one along with some 12V items.

House batteries only run the inverter. The boat is a 42 Bruno Stillman, all electrical updated in 2002. I have some investigating to do on this in an hour or so..

Sykes said:

House batteries only run the inverter. The boat is a 42 Bruno Stillman, all electrical updated in 2002. I have some investigating to do on this in an hour or so..

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Thats nor an arrangement I have seen / heard of.
If FLA the 8Ds are not generally very suitable for deep cycle use. I have more often seen inverter included with the house use and separate starting bank. Is there a large inverter load that was separated for a reason? Fridge or freezer comes to mind...
Doesn't seem like lights & fan should deplete a good 8D overnight. May be weak, not getting charged or light & fan load is excessive? Switch to LED lights?

Flatswing said:

It depends. Many prefer the separation of house & start batteries. On the other hand if you go over to the sister “cruisersForum” , u may find that most cruisers opt for 1 large bank of high AHr batteries serving both functions. If u have a generator with it’s own start battery (or better still, a generator with it’s own start batteries and jumper cables) there is no reason not to maximize your combined start/house bank.
In future consider reducing house loads, (LED’s etc.) add decent battery monitoring/coulomb counters & solar depending on your budget.

Click to expand...

Yep! I added 330 watts of solar panels for when I am on trips and on go on shore. This should handle my fridge and freezer during the day.

I mean, we go away with other boaters. So its not uncommon that we spend the day on shore and than go to someone's boat as night falls. I don't want to worry about the batteries.

My bow thruster uses my house bank which help uncomplicate things. So 3 banks in all, house, engine and genset.

I add a VSR between the engine and house for charging that goes without saying, but I did. I also added one to the genset battery with a breaker switch. Its normal left off for many reasons, but for the winter I turn it on and use the solar panel to keep all 3 batteries up.

Any setup is all dependent on how you want to use it.

Long ago, I heard, 'Dont leave the dock without a spare alternator, starter, lots of impellers and fuel filters and one spare FW pump.

My bow thruster was on the start battery. With the electronic engine controls, the engine shuts down I think about 10.8vts. I had it happen to me.... Now my bow thruster and stern thruster are on the house batteries (3X4D) In my feeble mind, I have decided it is necessary to keep the main engine running at all cost.

I witnessed a boat with electronic controls crash into the side of a lock, bounce into another boat, and then wedge its pulpit underneath a steel pipe railing. It was later found the the controls were supplied by the same battery as the thruster which had seen some use. Low voltage caused the controls to lock in the last command which was forward. It all happened quickly. The fault happened with way on and the boat in close approach to the lock wall so shutting down the engines was of no help.

OldDan1943 said:

Long ago, I heard, 'Dont leave the dock without a spare alternator, starter, lots of impellers and fuel filters and one spare FW pump.

My bow thruster was on the start battery. With the electronic engine controls, the engine shuts down I think about 10.8vts. I had it happen to me.... Now my bow thruster and stern thruster are on the house batteries (3X4D) In my feeble mind, I have decided it is necessary to keep the main engine running at all cost.

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