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Old 11-01-2019, 01:14 PM   #21
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My port engine battery is stand alone as is my generator battery. The starboard engine start battery also charges the house bank through a combiner that cuts off so that start battery will not be drawn down. The Starboard engine has the bigger alternator.

I also carry a 20 foot pair of heavy duty jumper cables that I can use in the event a battery goes weak and needs a boost or to combine both alternators to the house bank if I have been anchored out a long time without using the genny. I have also used them to jump another boat that allowed their banks to discharge.
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Old 11-01-2019, 01:16 PM   #22
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I have also thought about a spring wound starter that would make the engine startable even with NO BATTERY. They are not too expensive but still an extra expense.
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Old 11-01-2019, 01:44 PM   #23
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Me and my trawler follow a simple rule. Keep things separate except when they need to be combined. My fuel supplies, batteries, and charging are by engine. I can cross them over if need be. My House is connected either starboard or port. My port set is twice the amp hours as starboard. My main engine alternators can be combined. My generator battery and alternator are on thier own. My battery charger charges each bank independently.
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Old 11-01-2019, 05:58 PM   #24
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2 separate batteries might be justified for reliability, but as I said I have three: House, engine start, gen start. I am reducing it to two, house and engine/gen start. Can be cross connected for unusual situations.
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Old 11-01-2019, 07:09 PM   #25
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You don't say what type of boat you have, I would be interested in knowing that. If you are really, really interested in saving every available square inch of room one single house battery could be enough to start both engines and run your house lights for a few minutes in the evening. If you have a windless that battery might be on the foredeck and serve as a back up with a set of cables.

Why not invest in a couple of the "gel" type batteries. You could mount them upside down on the ceiling of your engine room not taking any floor space. Just giving you a head ache when you crawl around the bilge and bang your head.

I am in totally the other camp from you. I just pulled all my batteries for the winter. (Single engine 36 foot trawler) :
2 house batteries with a spare stored on the opposite side for balance making 3 house batts
1 Engine starting battery (F.L. 120)
1 Genny Starting battery
1 Windlass battery
2 batteries wired to my inverter
1 fully charged jump pack

That's a total of 9 batteries. The only time I regret having them all is in the fall when I have to move them for storage and again in the spring when I re commission.

One more thing, I never let any of them get over 3 years old. When they get that old I relegate them to inverter duty since I rarely use the inverter.

But then, I am Anal and love redundancy!

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Old 11-02-2019, 05:57 AM   #26
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"The only time I regret having them all is in the fall when I have to move them for storage and again in the spring when I re commission."


There is also the replacement expense and perhaps a watering drill.
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Old 11-02-2019, 07:13 AM   #27
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Just my preference.... separate start battery, separate gen start battery finally, the house batteries. (hello combiner, to the ME battery)
The gen battery is totally separate from the rest of the batteries and charger.
If you have solar panels, they charge only the house batteries.
AND that big red parallel switch is for when the main engine battery goes flat and you need to start the main engine off the house batteries.
IMO, it is totally foolish to routinely use the start battery as part of the house battery.

The jump packs are fairly inexpensive and fantastic 'insurance' against a total screw up on the part of the operator and failed batteries.
I guess, one should consider getting a jump pack large enough to start the ME but if not, get one large enough to start the gen.
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Old 11-02-2019, 09:41 AM   #28
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Quote:
Originally Posted by OldDan1943 View Post

Did Noah have a get home-engine? - Yeah, his wife!
My preference for batt layout: I use good ol', fairly high quality Flooded LA batts, manufactured by East Penn. IMO... Can't beat the economy and service life in relation to the price.

1. Four - 31M deep cycle batts hooked in parallel for house bank and start batts for both engines - > Consistently held at charge when starboard engine runs. - or - Charged by on board Professional Mariner 60 amp straight line charger that operates from shore power or genset by flipping "charger" breaker to on. - or - Charged by NOCO 12 V, 40 amp Genius 4 Bank charger that runs off shore power or gen set my flipping "120V" breaker on and flipping its own seperate switch on.

2. One - 24M starter batt for gen set - > Charged by solar panel on face of fly bridge. - or - by its own smart trickle charger that runs whenever 120V breaker is on; getting power from shore power or gen set.

3. One - 24M starter batt; that is isolated in its own batt box for "any" emergency - Charged by its own smart trickle charger that runs whenever 120V breaker is on; getting power from shore power or gen set.

4. One - 24M starter batt that is in Crestliner tow behind runabout w/50 hp Johnson o/b - Charged by the o/b.

Stats:

a. Regarding # "1" - Four deep cycle batt house bank lasts for nearly a decade before replacement. Cost for all four at Battery Plus [considering discounts etc] was $450 +/- beginning of 2019. The four replaced were put in at beginning of 2010.

b. Regarding # "2" - Gen set starter batt lasts for many years [not sure exactly hoe many]. When that went bad a few years ago I simply moved the isolated emergency batt [#3] into place.

c. Regarding # "3" - Isolated emergency batt's name says it all... it is for either replacing gen set batt, or replacing Crestliner's o/b batt [see #4]. It is also for starting main engines if for some reason that becomes necessary [never has yet!]. Each time the emergency batt gets used for replacement into the genset or Crestliner o/b the emergency batt get replaced with a brand new batt.

Pretty simple and near fool proof batt layout. Darn well affordable too!

PS: The inexpensive, always kept 100% charged, emergency batt [#3] means no need for expensive jump-pack... that eventually looses much of its power anyway...
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Old 11-02-2019, 09:56 AM   #29
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Interesting that there are as many configurations as there are boats. I guess its whatever works for you.

I didn't notice anyone mentioning a battery isolator. I my case I have a single engine with a start battery and two house batteries. The engine alternator is wired to a three bank isolator that charges all three batteryies when the engine is running.
The generator shares the engine start battery. In the rare event that the engine and geny are running at the same time the alternators are electrically separated via the isolator. If the engine battery ever fails then I can switch in the the house bank via a battery switch.
My bow thruster is wired to the engine start battery, the only time the thruster is used is when the engine is running. See no need of redundant batteries.

This set up has served me well for a long time.
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Old 11-02-2019, 11:23 AM   #30
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Originally Posted by Pete Meisinger View Post
You don't say what type of boat you have, I would be interested in knowing that.

.....

But then, I am Anal and love redundancy!

pete
It is an AT 34.

My original question was would there be charging issues with the genset and engine running together, the consensus seems to be no problem. How many batteries you are willing to deal with for other reasons might have a number of right answers depending on owner and use.

I've even thought of simply having a house bank and nothing more, start the engines from it. Properly maintained and managed, this is more reliable than any other scheme (i.e., fewer failures/year). In 35 years of (large) boat ownership I've used the combiner switch to start the engine exactly once, and that was after winter layup when the boat watcher set the charging switches wrong. So 2 banks (house and engine/genset start) is plenty redundant enough for me.

If you are replacing batteries every 3 years, you are either murdering them, or throwing away perfectly good batteries. The Lifeline AGMs on my sailboat are going on 13 years now, still serviceable, if down a bit on capacity.
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