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theoldwizard1

SE MI

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Posted: 11/15/21 10:05am Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

Hi,

If you plan to boondock without shore power then buy the biggest meanest deep cycle battery that will fit.

Remember, dual purpose Marine/RV batteries are a COMPROMISE !

Golf cart batteries or LiFePO4 are true deep discharge.

pianotuna

Regina, SK, Canada

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Posted: 11/15/21 10:20am Link  |  Quote  |  Print  |  Notify Moderator

Remember you don't need the complications of an Li battery. Just buy a drop in an SiO2.


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, soon to have SiO2 batteries, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

joelc

Cedar Point, NC

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Posted: 11/16/21 02:10pm Link  |  Quote  |  Print  |  Notify Moderator

Thank you all for your input. All was very helpful. I will review several times and go on from there. We are Full-timers who have our 5er on our own lot and are stationary most of the time. Occasionally, we go out to volunteer. Thanks again.

Ray,IN

IN, USA

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Posted: 11/22/21 09:41pm Link  |  Quote  |  Print  |  Notify Moderator

Consider being without power all night during cold weather. A gp 31 12v deep cycle battery probably will last one night just running the furnace, nothing else. When you lose power put the fridge and water heater on propane immediately to save the single battery for keeping warm.


And so, my fellow Americans: ask not what your country can do for you — ask what you can do for your country.John F. Kennedy 20Jan1961

joelc

Cedar Point, NC

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Posted: 11/27/21 03:31pm Link  |  Quote  |  Print  |  Notify Moderator

I am thinking of getting 2 Group 27 battery, instead of 1 group 31. Does that make sense?

wa8yxm

Davison Michigan (East of Flint)

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Posted: 11/27/21 03:47pm Link  |  Quote  |  Print  |  Notify Moderator

joelc wrote:

I am thinking of getting 2 Group 27 battery, instead of 1 group 31. Does that make sense?


NO Two Group 27 is about 200 amp horus and perhaps 50 usable
Two GC-2 is 210-230 amp hours. a bit taller but not as wide and you can use fully half of that power without seriously harming the batteries. Nearly twice the power.. but less price.. Only you do need to add distilled water from time to time.

That is,,,, unless you can find TRUE DEEP CYCLE Group 27s. (they do exist but hard to find and often expensive)

GC-2's are a bit taller. you might need a different battery box but that's one time. Consider them..

Another thing. battery weight = Capacity that is the heavier the more power it holds.. Battery TYPE (Starting, MARINE/deep cycle or True DEEP CYCLE) how much of that power you can use (MARINE/Deep cycle Sometimes called RV/deep cycle or MARINE/RV are really starting batteries first and deep cycle.. not so much) True Deep cycle you can use half the stored power before rapid aging sets in and .... What's more... they stand a better chance of recovery from an OH C**P level discharge (So long as you don't leave 'em there for days on end)

Starting batteries general do not recover from that kind of thing


Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times


Skibane

San Antonio, TX

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Posted: 11/27/21 06:10pm Link  |  Quote  |  Print  |  Notify Moderator

wa8yxm wrote:

joelc wrote:

I am thinking of getting 2 Group 27 battery, instead of 1 group 31. Does that make sense?


NO Two Group 27 is about 200 amp horus and perhaps 50 usable


If you're only getting 50 AH out of a 200 AH battery bank, you're doing something seriously wrong.

The life expectancy of a decent Group 27 deep-cycle battery doesn't really start falling off until you're regularly discharging it beyond 80 percent.

This includes good-quality trolling motor batteries.

For a 90 AH Group 27 battery, an 80 percent discharge would yield 72 AH - or 144 AH for a pair of them.

Compare that to a single 115 AH Group 31 deep-cycle battery - which would supply 92 AH when discharged 80 percent.

144 AH is more than 92 AH.

wa8yxm

Davison Michigan (East of Flint)

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Posted: 11/28/21 07:41am Link  |  Quote  |  Print  |  Notify Moderator

Skibane wrote:

wa8yxm wrote:

joelc wrote:

I am thinking of getting 2 Group 27 battery, instead of 1 group 31. Does that make sense?


NO Two Group 27 is about 200 amp horus and perhaps 50 usable


If you're only getting 50 AH out of a 200 AH battery bank, you're doing something seriously wrong.

The life expectancy of a decent Group 27 deep-cycle battery doesn't really start falling off until you're regularly discharging it beyond 80 percent.

This includes good-quality trolling motor batteries.

For a 90 AH Group 27 battery, an 80 percent discharge would yield 72 AH - or 144 AH for a pair of them.

Compare that to a single 115 AH Group 31 deep-cycle battery - which would supply 92 AH when discharged 80 percent.

144 AH is more than 92 AH.


While your math is good your assumption is not
You do not discharge MARINE/deep cycle to 80% discharge
You want them 75-80% FULL. this gives you only at most 25% of the capacity to use.... With full Starting batteries the minimum is 80% State of CHARGE or 20% of capacity and you really should not go that low

DEEP CYCLE like Golf Car batteries can go to 50% and LI to about 5% (or less) but most of your 12 volt GROUP XX types should be kept to 75% or more STATE OF CHARGE. not discharge but CHARGE.

The other thing is with Lead Acids voltage reduces with state of charge. With LI types... not so much...(I have a small LI I use for a radio. it hangs in there till it is gone and that radio really likes over 13 volts (does not work well on 12.6)

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