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Old 01-16-2014, 05:43 AM   #41
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If you are not paying around $400 for an 8D, it's not a deep cycle. A $150 8D is a starting battery with thinner plates.

Possibly , but what you are paying for is the LEAD in the battery , the case and spacers are cheap 50c a pound plastic.

The yachty markup $400 for $150 worth of lead in a different plate thickness is partially caused by by the lower production of deep cycle batts , VS the huge number of 8D for Trucks, Coaches, Cranes, Ag & earth moving etc.

Since many of these commercial uses DO require more than just a thin plate start batt ,(like a 31) the 8D usually is a fair compromise , but certainly not for repeated real deep cycle work.

Many OTR trucks run lots of lights with an Espar cycling of and on for 12 hours , sometimes with a TV , and lap top , and bunk heater. No place for just a start batt , but the cheapo 8D seems fine with the service.

The 8D in this service are seldom deep discharged , and with a 10 hour charge time , even an imbecile 1 wire V regulator can bring them to 100% , so they live long and prosper (3-4 years).

Check the CCA as well as the 20 hour rate for your next batt endeavor , as simple and cheap can work for many.

IDEAL solutions are fine IF you fully use them , otherwise a waste of currency.

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Old 01-16-2014, 10:50 AM   #42
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City: SF Bay Area
Country: USA
Vessel Model: Tollycraft 34' Tri Cabin
Join Date: Feb 2011
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IMO - Singularly the most important factor for extending the life of deep cell batts is never allow discharge over 50% - Period.

I have a lit screen Digital Multimeter batt tester hooked directly to our house batt bank and placed easily viewed on shelf in master stateroom; observable from salon. Flip of its switch and I see %age charge, drain during equipment use, and rate of recoup thereafter... as well as rate of charge while charging. I also see how fast it releases “over charge” after charging is completed and how long it took batt bank to level off at 100% charge. I don't always leave it on... but I do check house bank often!

Starter batts are a different animal in that soon as engine is started alternator should quickly return them to full charge.

Separately I keep a Multimeter in engine compartment (where I often “play around” early morns). I sometimes hand check starter batts as well as our “emergency batt”.

I believe starter bats should not be in house bank; OK to use deep cell as starter. Also, I believe in and do keep a completely isolated never used "new" combo batt for emergency in its own box with a trickle charger continually attached that activates whenever AC is on. As we are not dock sitters and seldom use gen set more than couple hours a day the “Emergency Batt” arrangement works well; it maintains high charge.

As with any piece/item/function on a boat... general surveillance for maintaining acceptable status quo is the name of the game to avert occurrences of untoward conditions.

Happy Boating Daze! - Art

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Old 01-17-2014, 12:06 AM   #43
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City: Bellevue, WA
Country: USA
Vessel Name: Vamos a Ver
Vessel Model: DeFever 46
Join Date: Oct 2012
Posts: 364
I decided to install a magnum battery monitor (SOC) on the inverter/house bank (900 AH). I moved the crane from the starting battery to the inverter/house bank so the windlass is the only other draw on one of the starting batteries and the other is only a starter (and can be combined if needed). I am having the marine service folks remove and install new 8Ds. This keeps it fairly simple and amply powered so I won't have to worry about engines not starting.
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Old 01-17-2014, 04:16 AM   #44
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Join Date: Oct 2007
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For those with a deeper interest in batts , this months HOME POWER mag is starting a 3 part series on bat maint , operation and cycling.

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