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Old 05-07-2011, 10:21 AM   #1
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Should I d/c battery when on AC?

Hi all. I did some searching, but still a bit confused. My trailer is currently sitting at home, with the AC power plugged in. I have read that if you keep the AC power on it might boil the battery, so I have disconnected the battery for the time being. However, doesn't the battery charger then think the battery needs to be charged (since it would see 0V) and burn up electricity for nothing? I hear the power panel humming in the trailer even when nothing is turned on. Maybe I'm just being paranoid lol. Is there a way to turn off the charger? It's the stock panel that came with the trailer.

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Old 05-07-2011, 11:06 AM   #2
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i wouldn't think the charger would think the bat needed charging; it would see the voltage that it is putting out and assume the opposite.

i leave my trailer plugged in for months at a time. on the reg lead acid bat, i do tend to boil water out. if i add abt once/mo it wasn't a problem in the past.

my bat tended to last abt 2 yrs so i went to the optma bat so time will tell.

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Old 05-07-2011, 12:11 PM   #3
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My RV's have been plugged in to the house for over 30 years with no issues. In fact I just replaced the original batteries this spring on my 2005 fiver. Six years on deep cycle batteries is not too shabby IMHO.
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Old 05-07-2011, 01:46 PM   #4
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A lot of things in your camper still operate on 12vDC EVEN when the power cord is attached to the camper. The battery is being used indirectly; it is powering those 12v items, like the lights and the TV / Concertone system (on mine, at least), the power awning and power tongue jack, slide out motors, and maybe more that slips my mind. While doing all of this, the WFCO three stage converter that most trailers come with is re-charging the battery back to it's original state. SO, you really should not disconnect the battery, as converter damage may be possible. As jimh stated, just be sure to keep a monthly or so check on the distilled water level in the battery. Randy
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Old 05-07-2011, 03:20 PM   #5
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In the case of my 2011 Sunseeker 2300, such things as the lights, power awning, water pump, refrigerator control panel, etc. will operate normally with the battery disconnected and the unit connected to shore power. In that configuration, the 12 Vdc current that drives these devices is supplied directly by the converter.

According to the manual for the converter (WF-9800 series): “The absorption mode is the normal operation mode. This mode provides 12 Vdc and current required by the 12 Vdc RV appliances, as well as slow charging the battery.” Regarding the Float Mode, the manual says, “When the converter senses a demand (by turning on lights), the converter automatically returns to the ‘Absorption mode’.” So, at least with my unit, the battery does not (according to the manual) supply power to the appliances when it is connected to the system and the unit is plugged into external power. The converter supplies the power in this case.

With this converter, there is also a bulk mode that delivers 14.4 Vdc to the system to more quickly charge the battery. If the battery is sufficiently depleted, this mode runs for four hours and the converter then switches to the absorption mode.

DageonYar, regarding your original question, the WF-9800 manual does not specifically address what happens if no battery is connected to the system. Your assumption that zero voltage on the battery terminals would cause the converter to go into its maximum charging mode seems reasonable. With a WF-9800 this would, according to my understanding, result in cycling between the bulk and absorption modes. In addition to running up your electric bill, this would also probably decrease the longevity of the converter. So, as 08flagvlite says, it is probably best to keep a battery connected to the system when the converter is powered up.
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Old 05-08-2011, 07:40 AM   #6
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You have a 1997 FR camper and you will need to check your converter for manufacturer and model number.

If it is a three stage converter you are ok to leave it connected all the time, just check it every month or so. The trickle current will keep it warm, charged, and prevent freezing.

If it is a two stage charger, you should remove it to a warm storage location and put a battery tender on it.

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Old 05-08-2011, 05:27 PM   #7
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our cherrokee 30f has been at our seasonal campsite for 6 seasons counting this year it has been puged in for all 5 prior years and to date the only thing i do is at the end of the season i trikle charge for about 8 hrs then i disconnect one of the cables from the bat this has worked great put in a new batt last summer
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Old 05-08-2011, 05:32 PM   #8
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Just check the battery water level and top off with distilled water

I would think as long as the water / acid doesnt go below the plates you should be good
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Old 05-08-2011, 05:44 PM   #9
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as Lou said, a lot depends on the converter/charger you have.
that old of a rig, may not have a 3-stage converter/charger and may boil the batteries.

knowing the make and model converter would help.

another common option, is just installing a battery disconnect switch.

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