Isolating Batteries to Create a Start and House Bank.

[DavidM]

I think most US sold engines with the 4LHA designation (the A) got the lower 80 amp alternator. Same one as on my 6LYA engine.

David

 

[dhays]

I believe that Hitachi is the same alternator that was on the 54hp Yanmar on my sailboat.

 

[ranger58sb]

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 NextGen 3.5 genset cannot be retrofitted with an alternator.

Good post. Jeez, serious constraints.

Sounds like 8Ds would be the only useful battery capacity increase, IF one would fit in each box. Not much Ah increase, but maybe every little bit may help.

Can't say as I'd recommend a single pair of golf cart batteries, and that wouldn't be much of an increase in capacity over the 4Ds anyway.

I like 31s compared to 4Ds or 8Ds when it comes time to move the suckers... but a single 31 wouldn't be great for the house loads... and even two would be a slight step down from the original 4D capacity.

-Chris

 

[kwmeyer13]

I think I could fit 3 31’s on each side which would increase capacity but that does not address separating banks which is what I am hoping to eventually do. Plenty of things to consider, thanks for everyone’s 2 cents. I guess now comes more reading, measuring, tracing, and staring. As always your input is much appreciated. Feel free to throw out more suggestions.

 

[DavidM]

Yes, two group 31s will fit on one side but not in the 4D/8D boxes. You will have to use new boxes and turn the batteries 90 degrees. But why?

One group 31 will start your engine just fine and two GC batteries have more amp hours than two group 31s for house use, plus and this is a big point- they are real deep cycle batteries with heavier plates, more room for electrolyte over the plates and of course fill caps. And two GC batteries will fit in the existing box.

Also I think you are mentally trying to stick with your current symmetrical battery arrangement. Most cruising boats have starting batteries for starting and deep cycle batteries for house loads. That is what I have on my Pilot 34- one group 31 and two GCs. Works well.

And FWIW, two GCs will start my Yanmar 6LY. Maybe not in 20 degree weather, but that is what the group 31 with 950 CCAs is for, well not really 20 degrees .

David

 

[Wxx3]

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.

I too.

My KK was also set up like the OP, with two house banks, one used for starting.
Stupid to me. That was the first change we made before leaving the dock.
Combined the two banks into one and bought one G31 to start engine.

 

[john61ct]

If you are going AGM, Odyssey G31 PC-2150 is excellent for deep cycling House use, and of course handles starting service no worries.

Putting all together into what usually functions as a single House bank gives maximum lifespan and usable capacity (peukert)

An adjustable high ampacity LVD can isolate one or two member batts, to protect from too low a discharge in House use.

If you only usually discharge 30-50%, that protection will never kick in, so the batts will wear evenly.

If you go lower regularly, then best to rotate the members say every six months.

Great redundancy too.

 

[FlyWright]

...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.

-Chris

One 8D box can fit 3 GC batteries. My house bank of 6 GCs fit into 2 8D boxes.

I too.

My KK was also set up like the OP, with two house banks, one used for starting.
Stupid to me. That was the first change we made before leaving the dock.
Combined the two banks into one and bought one G31 to start engine.

Agreed...same here. I use a single G31 (850CCA) to start BOTH of my main engines, Perkins 4.236's. No winter cold-weather starts here in Northern California but I always start the port engine first since that's the alternator providing the start battery charge.

My generator start comes from my right arm at the end of the Honda eu2000i start cord. It hasn't failed me yet!

 

[kwmeyer13]

So after spending so time on the boat I found out that my alternator is a hitachi LR160-741 which is 12v/60a and my starter is also a hitachi but no amp requirement noted on the tag. I would like find out what Yanmar determined the cca’s to be for my engines. This is mostly curiosity on my part. I have looked online and the nearest thing I can find to a specific number was 660 on the Toad Marine Supply website. The 660 is based on the formula of amp hours x 5.5 = cca’s. Not sure if that formula is acurate.

David my comment about fitting 3 31’s on one side was an answer to Ranger42C’s question about what would fit on one side.

Although perhaps one option would be 1 group 31 for each engine and a house bank of gc batteries. That would allow for redundancy on the engines if one battery dies.

 

[john61ct]

If dedicating dead lead to starting, one quality G31 is plenty for multiple, very large engines.

Can always jump from House in a pinch.

 

[DavidM]

My original post to this thread suggested a group 24 battery dedicated to the genset. That gives you another level of redundancy. Start the genset and let it run to charge up the discharged start battery.

To repeat my setup for a single on the Pilot 34: 1) A single G31 for starting, 2) A pair of GCs for house, 3) A single G24 for the genset. For your twin engines, just wire both engines to the same G31 start battery.

David

 

[kwmeyer13]

David,
More than likely that’s the route I will wind up going. To start, I will stick with my 4D’s and add a gen set battery. Plan out the changes needed to be done on my system, assemble the necessary items, and when time is right hinge the rest of the setup. Once again many thanks to you and every one else who took the time share information.

 

[FlyWright]

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..

Short and sweet! This is how my twins are set up except I use a Yandina combiner instead of the Blue Seas ACR. I can parallel the batts with the Perko Switches for extra engine start oomph if needed.

Works well with no need for throwing switches in normal ops.

 

[kwmeyer13]

Which bank(s) are best for the windlass and bow thruster? Right now mine are off the house/port start battery. Seems to me since both items are most likely to be used when the engines are running they should be hooked into the start bank.

 

[FlyWright]

Which bank(s) are best for the windlass and bow thruster? Right now mine are off the house/port start battery. Seems to me since both items are most likely to be used when the engines are running they should be hooked into the start bank.

That's how I have my windlass, on the start battery, b/c it's only used when the engines are running. If I had a 12V thruster, I'd probably do the same.

 

[dhays]

Which bank(s) are best for the windlass and bow thruster? Right now mine are off the house/port start battery. Seems to me since both items are most likely to be used when the engines are running they should be hooked into the start bank.

Keep in mind that CMS suggested that the larger (if one is larger) of the alternators should be feeding the house bank. So while you are are maneuvering one of the alternators will be feeding the bank you would be using for the thruster/windlass. Of course, at idle I don’t know how much help it would be.

 

[john61ct]

When the engine's running, the ACR is closed, so the alt current should be charging all banks.

So as long as alt output and ACR capacity are higher amps than what the high-current load is pulling, the batts aren't being touched anyway, so it doesn't matter.

But if you need to run that big consumer when the engine is off and the banks/circuits are isolated, it should IMO be running off the much larger House bank.

 

[ranger58sb]

Yes, two group 31s will fit on one side but not in the 4D/8D boxes. You will have to use new boxes and turn the batteries 90 degrees. But why?

If two would fit that way, could three also work on each side? Mostly just trying to illuminate options... but also partly because we had good success with banks of 3x Odyssey PC-21050s... without changing any boat wiring.

And two GC batteries will fit in the existing box.

Does it follow from above that four GC batteries could be fitted each side, using different boxes and/or different orientation?

Another thought: some of the taller traction batteries (e.g., Trojan's L16) fit in the same horizontal footprint as regular GC2 golf cart batteries... and offer even more capacity. If vertical space isn't so tightly constrained. IIRC, it's 300-Ah for a pair of L16s or Lifeline's AGM equivalent.

One 8D box can fit 3 GC batteries. My house bank of 6 GCs fit into 2 8D boxes.

Ah. Thanks for correction. I was having a brain phart when I said 4 might fit in each 8D box.

FWIW, when I converted one of our banks to GCs, I also wanted a box instead of open trays... but finally found some that would hold 2x or 4x GCs. Inserting the box actually turned out to be more work than the batteries, just because of the stuff in the way of getting the box into place.

-Chris