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Battery test

October 01, 2016, 08:15:49 pm

There have been some questions about running an electric fridge on just 2 batteries, I have a 10 cu ft.Frigidaire in our U270 with 2 8a8d AGM batteries, Magnum MS2012 inverter charger, today I turned on all the the interior lights, the fridge, sound system and tv, after 6 hours the state of charge 63% when the generator came on, so I don't think it will be a problem dry camping.
 The coach was un pluged and only on inverter power.

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Re: Battery test

Reply #1 – October 02, 2016, 10:19:36 pm

We use 180-200 amp hours overnight.  Our Dometic chest refrigerator is on 24/7.

37% discharge on a gel is probably a 400 cycle life. 

You are using 160? 

Keep track of the batteries condition as the use goes on

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Re: Battery test

Reply #2 – October 03, 2016, 10:20:07 am

Flash are you saying I used 160 life cycles of may batteries usefull cycles.

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Reply #3 – October 03, 2016, 11:10:14 am

Agm's are capable of 500 50% discharge cycles.  1000 20%.  What i'was saying it's cost effective to draw down more batteries less discharge over the long run.

As the batteries get the "good" used out of them by deeply discharging them more often they may take more charge time.

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Re: Battery test

Reply #4 – October 03, 2016, 12:32:29 pm

In 6 hours the batteries were only discharged 37% that means they were at 67% state of charge well above the norm of 50 % discharge.
 After talking to East Penn, a life cycle is 1 discharge at 50% and recharge to 100% charge, so I guess I have 499 to go or more as they said my discharge of 37% when the generator came on will extend the life cycles.

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Re: Battery test

Reply #5 – October 04, 2016, 01:37:15 am

Somewhat the reason we went with the OEM original install of three 8g8's.

Less discharge percentage and double the cycle life.  We dry camped about half the nights in our 18 days on the road so far.

About average for us. 

If you plug in normally the gels are not as needed. Or three.

Sorry to cause you worry.  Not my intention.

Been rv'ing in countless rv's long ago and after enough issues learned to put the most and best batteries possible in a coach we are going to use

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Reply #6 – October 04, 2016, 08:18:42 am

Flash you did not answer the question, are you saying I used 160 life cycles on my batteries.
 Answer please.

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Reply #7 – October 04, 2016, 10:00:46 am

No.  unless you discharged your batteries 50% 160 times. Out of your 500 life at 50% DOD

You took only a tiny amount of your cycle life.  so far. 

My overnight usage took 130 amphours over night last night so I took 20% out of my 675 capacity.  Out of my 1,000 life at 50% DOD

If I were to use 37% every night I might add a fourth battery and a bigger than 160 amp  alternator personally.

Most new high line rigs with residential refers run four batteries. 

My guru buddy routinely adds battery capacity and a minimum of 500 watts solar for residental refer use.

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