House Battery

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

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.

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.

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

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

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.

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)

These are all 12V Deep Cycle Batteries, not Marine STARTING Batteries. The Group 27 battery I found at O'Reilly's and the Group 31 at NAPA.

wa8yxm wrote:
While your math is good your assumption is not
You do not discharge MARINE/deep cycle to 80% discharge

It's not an assumption.

In the real world, it's done all the time.

One of the more humorous aspects of new battery technology is the way it downgrades the capabilities of the technology it's meant to replace:

- AGM batteries are introduced - and suddenly, you can't discharge conventional flooded-cell deep-cycle batteries beyond 80 percent.

- LiFePO4 batteries are introduced - and suddenly, you can't discharge conventional flooded-cell deep-cycle batteries beyond 50 percent.

At some point, some new battery technology will be introduced which will lead its proponents to conclude that conventional flooded-cell deep-cycle batteries can't be discharged at all! :B

joelc wrote:
These are all 12V Deep Cycle Batteries, not Marine STARTING Batteries. The Group 27 battery I found at O'Reilly's and the Group 31 at NAPA.

I'm not finding a true deep cycle battery on O'Reilly's website. What model number are you considering?

Keep in mind an AGM may require a different charge profile than a flooded lead acid. You want to match your battery to your charger or vice versa.

On Edit: You might consider a 150Ah Trojan T-1275 true deep cycle battery as a compromise to two 6V GC2. There's a better chance of it being a drop in replacement for your existing battery. It can be heavily discharged the same as the GC2 in a smaller footprint of two GC2s. Just another option to consider.

Call your local golf cart dealer for pricing if interested. Shipping can be expensive if you buy them online. Maybe he can order yours with a larger battery order to minimize shipping.