Isolating Batteries to Create a Start and House Bank.

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kwmeyer13

Senior Member
Joined
Oct 30, 2014
Messages
260
Location
USA
Vessel Name
Guns 'N' Hoses II
Vessel Make
2004 34' Pilothouse Sedan
I realize this is a post that is electrical in nature but seeing as how I seeking a Mainship specific answer I am putting it here. I have a 2004 Mainship Pilot House Sedan with twin yanmar 240’s. I have a generator and bowthruster. My current setup is 2 4D batteries. One starts the port engine and the other starts the starboard. Port battery also feeds the cabin and also the bow thruster. The starboard battery feeds the helm main and starts the generator. I have attached 2 pictures showing the current batteries and and panel. I really do not like this set up. I would like to have a starting bank, a house bank, and generator/bowthruster bank. Do others with the factory setup like the arrangement? Has anyone modified it and if you have, how so? The main reasoning behind this thinking is wanting to spent more time “on the hook” without the chance of killing the starting batteries. I guess I could add a seperate battery just to start the generator and tie that into the battery charger since it has the capability of charging 3 banks. This would eliminate being caught with dead starting batteries by being able to just fire up the generator and putting on the battery charger till the starting battery(s) are ready. The funny thing is that the manual that I have for the boat says that “your yacht has the provision for one 12v deep cycle, heavy duty battery for each engine and a marine cranking battery for the generator.” Needless to say that part has me confused. Would anyone care to jump in and add their 2 cents?
 

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The funny thing is that the manual that I have for the boat says that “your yacht has the provision for one 12v deep cycle, heavy duty battery for each engine and a marine cranking battery for the generator.” Needless to say that part has me confused. Would anyone care to jump in and add their 2 cents?

Ours came set up similarly, only with 3x 12V G27s for each start/house bank... but ours did include the separate genset start battery.

I decided it was too much work to change the whole setup... so added storage and charging capacity instead. And got better batteries.

One step was to replace the genset start battery with AGM (when replacement was required) and then I took that off the original charger. Low self-discharge rate, the genset will charge the battery anyway, all good.

Another step was to replace boths bank of G27s with 100-Ah 12V AGMs (300-Ah each bank)... and then eventually (after about 12 years) I changed one of those to 4x 6V gold cart AGMs for in increase to 440-Ah on that bank.

The third step was to dedicate the original 40A charger to the remaining 300-Ah G31 bank, and dedicate a new 70A inverter/charger to the 440-Ah GC bank. So now I get slightly faster charging... and I'll upgrade that charger to higher charging capacity when necessary.

Some of that was space dependent, but it happens I could shoehorn the GCs into that slot.

FWIW, we've not really had any problems with DC power on the hook... two fridges, etc.... but it also happens we run the genset for a while mornings and evenings... to cook in our all-electric galley, don'tcha know... but that also contributes to the whole deal. We can be out for a couple weeks that way without killing batteries.

-Chris
 
Chris, thanks for your time on detailing your set up and changes. My generator does not have charging ablilty. It is the smaller of the nextgen options that came with my boat. I guess adding another battery charger with a seperate start battery might be an option. However space is a bit of an issue.
 
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It is virtually impossible to give you specific, step by step advice as you have an existing system to consider and I have just a vague understanding of how those two switches and breakers work (my Pilot 34 single is entirely different). But here is what I would do, acknowledging the space limitations that you have:

Set up one of your 4Ds to start both engines. You could also wire it to also start the genset, but that robs you of some important redundancy. On my Pilot 34- single, I have a genset start battery- a group 24 underneath the cockpit sole to the stb of where the two big batteries are.

Then ditch the other 4D and use that space for two golf cart batteries wired in series. That will give you 240 AHs of true deep cycle capacity. Wire those batteries to the house.

This will leave you with three battery bank(s): propulsion start, genset start and house bank, so hook up each to one of the three charger outputs.

The idea is to dedicate the starting battery to starting and the helm main (presume that this powers the panel underneath the helm- instruments, etc which are things that only need power when the engine is running. The genset has its own dedicated battery that is charged by the shore power charger. All house loads which are the ones that will be used at anchor are supplied by the pair of GCs.

You can add a combiner or ACR to connect the starting/alternator output to the house bank when the alternator voltage gets up to the mid 13s. This will then be a set and forget system, plus you have the redundancy of a dedicated genset start battery that will let the genset charge up the others if for some reason the start battery gets discharged, ie a bad battery.

How big is your battery charger? On my boat, the PO replaced the OEM (40A I think) with a 100 amp Xantrex Freedom inverter/charger. I only have to run the genset for about 30 minutes in the morning (also to make coffee) and maybe 45 minutes at night (also to heat water) to keep the house batteries charged up. I can go forever on the hook with this much genset running time.

David
 
That is amazing that that is the stock setup, since it is seriously misguided. I have a similar boat, a Bruckman BlueStar. It came with 3 4D's (one for house and one each for starting the Yanmar engines). The batteries were tired when I bought the boat and the first thing I did was buy two Lifeline AGM 4D deep cycle batteries and put them in parallel for the house. I then bought an Odyssey/Sears DieHard Platinum Group 31 for starting both engines and the generator. That battery has no problems starting my Yanmars - a 4D is serious overkill for starting. In the unlikely event that the start battery has a problem, I have a built-in parallel switch that will allow starting off of the house. (If I was seriously worried about not being able to start something, I could have put a small AGM battery that was dedicated to the generator, but I did not bother).

At the end of this process I had greatly increased house capacity in the same space and reliable starting. Not much to dislike.
 
Thanks for your input David. My current charger is a Promariner 50 amp 3 bank. I just replaced it last year. The original was a 50 amp 3 bank as well. What you describe with ACR andcombiner seems beyond my abilities at this point and I think it would be time to bring in a pro if I went that route. Last thing I would want to do is pull a working system apart and do a half assed replacement.
 
Steve, thanks for jumping in on this. I also have a parallel start switch at the helm. I had to use before when the batteries that came with the boat had issues when the original battery charger bit the dust. So this is another piece of the puzzle that I assume would have to be figured in with any rewiring.
 
David, this is just off the top of my head but if I moved the port engine to starboard battery that would free up the house loads and with the parallel start set up correctly that would allow me some redundancy and then if I were to add a 3rd battery to start the generator and be connected to the 3 leg of the charger then I don’t see how I would be unable to start the engines somehow.
 
I had a similar problem with our 2003 30' Pilot II that we purchased in the fall of 2016. Both batteries were wired in parallel with one on/off switch under the galley sink. There was no 1-2-both switch to isolate either of the batteries.Wanting to spend time overnighting I was also concerned about draining both batteries. So over the winter of 17' I bought two new high-end batteries and installed both wired to the existing charging system.I isolated one battery with #1 cables wired to an on/off switch so when on the hook I shut down the isolated battery with no worries about draining it. As you probably know the 30 has a single engine so this fix will not work for your set up. As written above I would try to rewire so both engines fire from the same battery so you can isolated the other or go with a third battery and isolate it. I should add that I have no gen set but do have the bow thruster. I replaced all 12v bulbs with LED's. The 12v refrig run continuously. I never had a problem firing up the 315 Yanmar in the morning even if I left the isolated battery off.

regards from the north shore Holty
 
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David, this is just off the top of my head but if I moved the port engine to starboard battery that would free up the house loads and with the parallel start set up correctly that would allow me some redundancy and then if I were to add a 3rd battery to start the generator and be connected to the 3 leg of the charger then I don’t see how I would be unable to start the engines somehow.

What you describe sounds like an easy setup. The downside is that the engines which will now only be hooked to one battery, will not charge the other battery unless you use the parallel start set up. And you have to remember to switch it off at anchor or maybe it is a momentary push switch which won't work for charging the house battery.

That is what a combiner/ACR is for. ACR/combiners aren't difficult to set up: three wires- pos to one battery, pos to the other and a ground.

David
 
Holty, I too replaced all the bulbs after I almost burnt my bald head on a fixture in the main cabin so the frig is the main battery drain. The kids like the tv, but I think that’s minimal. What I do hope to do is wind up putting I an inverted in soI can run the coffe maker in the morning without having to fire up the generator. I think mostly it’s paranoia on my part.

I have spent a few nights in Huntington harbor for the lighthouse festival is past years. Was sorry they did not have last year, hope it’s back on this year.
 
David you make things sound so easy. Once I have the boat back behind the house and I can sit and stare at everything and I am sure things will be clearer. In the meantime I wil reread Nigel Calder and a few other books.
 
I really like David’s suggestions. There are a lot of ways of doing it so sitting down and playing with with ideas on paper is time well spent.
 
Went with a single burner butane stove to brew the coffee in the morning. Very convenient and can be used down below or up top if mama wants to sleep late. The light house concert is on for Labor day weekend this year. It is always a great time.

regards Holty
 
Chris, thanks for your time on detailing your set up and changes. My generator does not have charging ablilty. It is the smaller of the nextgen options that came with my boat. I guess adding another battery charger with a seperate start battery might be an option. However space is a bit of an issue.

FWIW, I purposely overwintered our Odyssey batteries with no charging... and say about .1V drop after 4 months.

OTOH, our genset charges it's own battery. Can you add an alternator to you Nextgen?


That is amazing that that is the stock setup, since it is seriously misguided.

It's apparently a very common set-up for his brand, our related brand, and many of the other boats similar to our brand. In our case, I expect the maker's original design assumptions and constraints is about the typical marina-hopping many (most?) owners of boats like ours often do.


Steve, thanks for jumping in on this. I also have a parallel start switch at the helm.

Very good to have.


Holty, I too replaced all the bulbs after I almost burnt my bald head on a fixture in the main cabin so the frig is the main battery drain. The kids like the tv, but I think that’s minimal. What I do hope to do is wind up putting I an inverted in soI can run the coffe maker in the morning without having to fire up the generator. I think mostly it’s paranoia on my part.

You could do some measurements, about that paranoia thing.

:)

I forgot to mention we also changed all our lighting to LED, and especially the anchor light probably made a decent difference. Partly because we don't use the other lights all that much.

And morning cofee -- and afternoon popcorn -- without needing the genset is really why we did the inverter/charger thing. The charger at first was a secondary consideration, but as we increased battery capacity on each bank (a lot, on that one bank) it made sense to improve our charging capacity and speed at the same time.

Another factor to consider is that you likely have two other load groups, at the helm. One would probably be electrics (horn, nav lights, etc.) and the other would be for your electronics (plotter, sounder, AP, etc.). In our boat, those are split; electrics on one bank, electronics on the other.

Anyway, it wouldn't surprise me if your measurements (ref that paranoia thing) get you to the point where splitting your banks differently may well seem like just too much trouble. Especially for longer wiring runs. For us, it was easier to just add as much capacity as we could stuff into the space available... and then modify our own behavior to deal with what we've got. As it turned out, given our electric galley, we didn't have to really change our own behavior.

How many G31 batteries could you stuff into one of your battery trays? 3x G31s would exceed your 4D capacity. How many golf cart batteries could you stuff in there? 4x GCs would significantly increase your capacity.

-Chris
 
Chris, looks as if you had your morning coffee already. I would have to contact nextgen to see if an alternator could be added but from the size of the sound shield around it I don’t think so. I could probably switch out 1 of the 4D’s for 3 31’s but I am not sure about getting 4 gc’s In for the other 4D. Side note on the gc’s, I have been told that these are not suitable for starting use. So if that’s the case I would still have to move both engines to a starter bank.
 
Use one switch for HOUSE BANK & One switch for START BANK

Put all master panel loads on HOUSE (panel under rear cockpit hatch)

Use one START BANK for both engines and the genset

Feed all charge sources to HOUSE BANK other than start banks engine alternator

One alt still feeds direct to HOUSE BANK (bigger of the two, if one is)

One alt feeds START BANK

Install a Blue Sea ML-ACR 7622 between banks on the load side of the switches. This allows for emergency manual cross-connect (use house for everything with start off/isolated, or start for everything with house bank off/isolated). This will also allow both alternators to charge both banks, automatically, thus doubling your bulk charge capability into the house bank.

Keep it simple there is no need for more than two banks on a 34' Mainship.

Without a diagram of how it is actually wired at this point in time it's impossible to say how you do this in the most efficient manner..
 
CMS,
Thanks for your input, it’s much appreciated. Unfortunately I do not have a wiring schematic to go by. If anyone knows where to locate one please let me know. I agree with keeping it simple. What you suggest with swapping the loads on the master panel is what I originally thought but might be a job from for someone more knowledgeable than me. Seems every time I read Calder’s book I just get confused. :confused:
 
CMS,
Thanks for your input, it’s much appreciated. Unfortunately I do not have a wiring schematic to go by. If anyone knows where to locate one please let me know. I agree with keeping it simple. What you suggest with swapping the loads on the master panel is what I originally thought but might be a job from for someone more knowledgeable than me. Seems every time I read Calder’s book I just get confused. :confused:

Mainship was not very consistent in their wiring, neither were the Luhrs or Hunters. I work on a 2006 single screw 34 and it is totally different than the 2005 and 2003 I also work on. One thing all of them have in common is poor alternators....
 
I have an ‘07 Pilot with twins and a similar setup as Kevin, except 8d batteries instead of 4d, and a separate generator start battery with solar charge panel. I’ve thought about how to improve the system and was considering replacing each 8d with a start battery and a house bank connected with an ACR combiner. This would require only minimal wiring changes. The downside would be that it does split the house into two banks, however the loads are currently split between the two 8d’s.
 
CMS,
Could you elaborate on the alternators?
 
Tonic1,
Do you know how many banks your battery charger is capable of supplying?
 
It is a 3 bank charger. One for each main battery and one for the generator start battery. I think it is 40A.
 
Tonic1,
Sorry for all the questions. What size generator do you have and do you know the size of the battery?
 
No problem, I have the 5.5kw NextGen, and the start battery is a group 24 starting battery.

Brett
 
Chris, looks as if you had your morning coffee already. I would have to contact nextgen to see if an alternator could be added but from the size of the sound shield around it I don’t think so. I could probably switch out 1 of the 4D’s for 3 31’s but I am not sure about getting 4 gc’s In for the other 4D. Side note on the gc’s, I have been told that these are not suitable for starting use. So if that’s the case I would still have to move both engines to a starter bank.


I've read golf cart batteries can be used OK for starting, especially if you've got enough of 'em in a bank to increase available cranking amps. I also then asked Lifeline specifically about that, providing our engine specs for minimum cranking amps... and the Lifeline tech said we'd be fine with 4x GCs for an engine. In practice, all seems fine. And remember that parallel switch.

Your engine specs will say minimum cranking amps. And your starters may have a tag with similar info.

Your tray's look equal in size? Will an 8D fit in each one? Your 4Ds are giving you approx 210Ah nominal, and 8Ds would up that to nominal 245Ah... and 3x G31s would be about 300Ah... and 4x GCs would be about 440Ah. I think 4x GCs will fit in the space of 1 8D... but it's been a while since I was checking all that, so might be mis-remembering.

If I had space for 4x GCs on my other large bank, I'd probably do that too... but our water heater gets in the way on that side of the boat.

Another way to skin your cat could be 3x Firefly Oasis carbon foam G31s... still about 300Ah per banks but... which have been advertised to routinely support draw down to 80% depth of discharge (DoD). Several threads on those around here.

-Chris
 
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One thing all of them have in common is poor alternators....


Maybe they just used whatever came installed on whatever the engine maker put there?

-Chris
 
Some corrections to various posts above:

The two battery boxes on Pilot 34s are designed to take a 4D and maybe an 8D. Two 6V GC batteries will fit in that space with some left over, but definitely not enough for two more. A single Group 31 will also fit which is plenty to start either the twins or the single (mine).

The twin Yanmar 4LH 220 hp engines in the Pilot 34 come with an internally regulated Hitachi alternator. Like most of their type they don't put out anywhere near their rated current normally as they are designed to replace the small amphours used to start the engine and keep up with external running loads, not to replace lots of amphours.

The same alternator on my Yanmar 6LY produces about 20 amps when charging a 75% charged bank of two GC batteries. To push say 50 amps into these batteries you would need something in the order of 14.5 volts and the internally regulated Hitachi is fixed at about 13.5 volts so it can only push 20 amps in those conditions.

The NextGen 3.5 genset cannot be retrofitted with an alternator. There isn't any way to drive one. Many small gensets don't have alternators because of this problem. The available drive on the engine is taken up by the raw water pump. In fact the Kubota engine on the NextGen 3.5 doesn't even have a coolant circulating pump as I suspect that drive has been used for the raw water pump. Instead of a coolant circulating pump it uses the thermosyphon effect to circulate coolant.

But if the genset is running it is making AC and can power the onboard charger to replace the current used in running the fuel pump which is DC driven, not camshaft driven like many bigger diesels. You just need to make sure that the charger is powered, ie turn on its circuit breaker.

David
 
Just tossing this in since the alternators have been mentioned.......not sure which is in my boat since it’s in the yard.
 

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