Jaybirdsdu
Pottstown, Pa
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Joined: 07/28/2009
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How does one figure out how many amphours you need? And what determines the size/group battery to use?? And how many batteries to go with?
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Crazy Ray
Monroe,La
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Joined: 01/17/2006
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Google 12volt side of life.
RET ARMY  , DW Donna , Summer (Furkid)  . Class A, 2000 Gulf Stream, 4 SAMS 6VOLTS, DIRECTV, YAMAHA 2400 GEN , TOW 97 Wrangler/Honda CR V. Garmin GPS 7200  . "Living Our Dream". NASCAR FAN (14,18,,20,11) Love CO & NM 
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Fiver Captain
Central Florida
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Joined: 12/06/2008
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Short answer without writing a novel. Amp hours needed will depend on what you use off battery power and for how long. 1 amp per hour equals 1 amp hour. If you use 100 amps per hour, then you use 100 amp hours.
As far as selecting a battery, I suggest you get the one with the highest amp hour and reserve rating that you have room for. More batteries hooked in series equals more amp hours available. Many people suggest using golf cart batteries and hooking parallel due to their amp hour ratings, discharge profile, and reserve capacity. I personally use two 105 ah marine batteries hooked in series and have been very satisfied with their performance.
If you search here on batteries, you'll find more than you care to read.
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Sailbad
Oklahoma City
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Joined: 05/22/2003
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Deep cycle batteries do not like to be repeatedly discharged below 50%.
With that in mind, do an energy audit for your rig. If you find you are consuming 100 amps, then you need a battery capacity of at least 200 amps.
As was stated above read the 12 volt side of life.
Dave C.
2005 Silverado 2500 CC
Duramax 6.6 3.73 V-2
2003 Wildcat 27RL
B&W with Companion
Prodigy
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daveshan
Durango
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Joined: 04/02/2009
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Fiver Captain wrote:Short answer without writing a novel. Amp hours needed will depend on what you use off battery power and for how long. 1 amp per hour equals 1 amp hour. If you use 100 amps per hour, then you use 100 amp hours.
As far as selecting a battery, I suggest you get the one with the highest amp hour and reserve rating that you have room for. More batteries hooked in series equals more amp hours available. Many people suggest using golf cart batteries and hooking parallel due to their amp hour ratings, discharge profile, and reserve capacity. I personally use two 105 ah marine batteries hooked in series and have been very satisfied with their performance.
If you search here on batteries, you'll find more than you care to read.
Uhhh, I think you have the series/parallel reversed, Series increases voltage and parallel keeps the same voltage and increases amps.
Check HERE for a diagram.
'05 Lance 845
'06 Super duty SC/SB 6.0
Usually towing an '01 Wrangler, lifted/locked on 35"s
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Steveo35
Ohio
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Joined: 06/16/2009
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Do dry cell batteries preform OK if they are drained below 50%
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smkettner
Southern California
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Joined: 03/21/2005
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Dry cell batteries are not rechargeable. Do you mean AGM? They can go below 50% but so can wet cells. AGM certainly charges faster if your converter has the amps and volts to do it.
IMO 70%-80% discharge is not a big deal now and then for any deep cycle battery. The important part is to get it recharged. And fully 100% tip top charged once a week or so or when you return home and can plug in.
http://www.usbattery.com/usb_images/cycle_life.xls.pdf
Experience is the best teacher on what total capacity you need. You can add batteries, solar charging, better converter, etc to suit your needs. Some combination of these things will work for you.
2001 F150 SuperCrew
2006 Keystone Springdale 249FWBHLS
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Fiver Captain
Central Florida
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Joined: 12/06/2008
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daveshan wrote:Fiver Captain wrote:Short answer without writing a novel. Amp hours needed will depend on what you use off battery power and for how long. 1 amp per hour equals 1 amp hour. If you use 100 amps per hour, then you use 100 amp hours.
As far as selecting a battery, I suggest you get the one with the highest amp hour and reserve rating that you have room for. More batteries hooked in series equals more amp hours available. Many people suggest using golf cart batteries and hooking parallel due to their amp hour ratings, discharge profile, and reserve capacity. I personally use two 105 ah marine batteries hooked in series and have been very satisfied with their performance.
If you search here on batteries, you'll find more than you care to read.
Yep, you're right. Had an old timer's moment. Seems like that's happening more with each turn of the calendar.
Uhhh, I think you have the series/parallel reversed, Series increases voltage and parallel keeps the same voltage and increases amps.
Check HERE for a diagram.
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Matthew_B
The boonies near Dallas, Oregon
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Joined: 08/18/2005
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The 50% rule comes from getting the best value out of batteries.
If you discharge and recharge daily the batteries are optimally sized with a 50% discharge. If you discharge them deeper, they'll wear out faster such that it's cheaper to have just bought more up front. If you discharge them less than 50%, you're spending more on batteries than you need.
This rule doesn't really fit if you don't regularly discharge your batteries. At 50% discharge, to quality batteries will last around 800 cycles. Discharged to 80%, they'll last 200 cycles. Ask yourself if you will use the battery for more than 200 cycles in 8 years. After 8 years they're dying of old age anyway. If you use them less than 200 cycles in that time, you can discharge them to 80% with little loss in overall battery life.
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pianotuna
Regina, SK, Canada
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Joined: 12/18/2004
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Hi Jaybirdsdu,
Make a list of the electrical items you wish to use. Figure out the number of watts per day that total will be. Divide by ten and that will be the minimum size of battery needed for one day.
As to selecting batteries more amp hours is better. The individual batteries will last longer.
My thoughts on battery selection are written up here:Technology
and click on "Battery selection"
Regards, Don
Kustom Koach Class C 28'5" 256 watts solar, 875 amp hours in two battery banks 12 volt batteries 2500 watt inverter.
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