House Battery
I am looking for a battery for my fifth wheel. I guess it is called a "house battery". For the purpose of running my 12V system in the event power fails or for not being connected to a post. My pri...
Forum Discussion
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)
