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Old 03-05-2015, 09:13 PM   #21
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I personally have had very good results with "automotive" Delco alts. I use two 105 amp units on one engine and a 70 amp on the other. The twins charge the 1100 AH house bank. The voltage climbs from the 13s to the 14s when the second is brought on line. They have internal dumb VRs. I monitor the two setups using digital LED volt meters at the helm. I've been running this for three years and all seems well.
\\

With that large of a house batt. you have a bunch of headroom for all to seem well.

What is the final SOC after running for 8 hours after using the house on the hook for a couple of days?

Do you use a hydrometer or a SOC gauge or only a volt meter?

I bet the battery's are never really full as that would take a staged charge with a final absorption voltage at 14.4-14.6 and then when the current was down to about 1-3% of house capacity drooping to a maintenance (float) charge.

Hey it works good enough for you and that's all you need.

Many ways to cook a goose.


This is a great tool and is well vetted here.

Smart Gauge Battery Monitoring Unit Photo Gallery by Compass Marine How To at pbase.com
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Old 03-05-2015, 09:40 PM   #22
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And, conversely, if the bank isn't large enough, the additional capacity of a second alternator isn't necessary, even with an external VR.

But don't get me wrong -- I completely agree that a smart VR is best. I am really just responding to the idea that the second alternator is useless because the two alternators will fight each other (I think that myth was dispelled above), or because the VR won't allow one of the alternators to put out any current -- I believe it will, even with a dumb VR, so long as the batteries can absorb more current than the one alternator, alone, is putting out. So, in practical terms, put on two alternators if you think you may need that much current (and in that regard the focus should be on net output, ie, after subtracting current consumed by blowers, etc.), and use a smart VR if possible.

I would agree with that.

Today with so many folks today using an inverter to be more independent of the noise maker more effort is being put of better and more efficient use of larger battery banks. The old days of just running the gen-set all the time day and night is just not as popular.

Having large banks of batt's with sat. tv's, ice makers, underwater lights etc. requires more attention to properly putting those electrons back during the day when you are running the main(s) anyway. This is where the high-tech charging systems really shine.

If running a few LED's and charging a cell phone while a 12 refrigerator keeps the beer cold all night while you cook with a gas stove is more your cup of tea then this is all overkill, but it's still cool.

I like going several days with cold food and TV and all my required toys charged and looking at my SOC meter and my battery monitor and see still over 90% with a nice 12-15 amp charge (mid-day solar panel output) without running the main or gen-set, ahhh independence.
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Old 03-05-2015, 09:50 PM   #23
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If running a few LED's and charging a cell phone while a 12 refrigerator keeps the beer cold all night while you cook with a gas stove is more your cup of tea then this is all overkill, but it's still cool.

I like going several days with cold food and TV and all my required toys charged and looking at my SOC meter and my battery monitor and see still over 90% with a nice 12-15 amp charge (mid-day solar panel output) without running the main or gen-set, ahhh indapendance.
Mr. Davis:
On my last boat (55', with corresponding electrical requirements), my bank was big enough (and my electrical needs modest enough) that I could get by just running the genset about 4 hours every morning. With my current boat, I expected about the same, and commissioned accordingly (including a gas range). But I didn't do the math and I can't even make it through the night without the genset and have given up trying. I envy your "indapendance".
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Old 03-05-2015, 10:07 PM   #24
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Mr. Davis:
On my last boat (55', with corresponding electrical requirements), my bank was big enough (and my electrical needs modest enough) that I could get by just running the genset about 4 hours every morning. With my current boat, I expected about the same, and commissioned accordingly (including a gas range). But I didn't do the math and I can't even make it through the night without the genset and have given up trying. I envy your "indapendance".

Oh how glaring my spelling is when seen on a forum, darn fat fingers and a not so smart phone.

Sir your vessal is the Hilton to my camper, my modest electrical needs pale compaired to you. If I had your boat I would enjoy the luxeries and run the genny, large banks of batteries work best on a U-boat. My quest is for simple endurance and economy.

Regards,
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Old 03-05-2015, 11:46 PM   #25
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And I like the tensioner on the second alternator.
Thanks! Half the fun is doing the design work on these projects.

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Old 03-09-2015, 07:52 AM   #26
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"The old days of just running the gen-set all the time day and night is just not as popular. "

Perhaps the all up cost of $7.00 to $12.00 an hour for noisemaker operation is responsible?
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