Ezbagr
Illinois
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Which way of keeping the batteries charged is easier on the batteries while parked in driveway at home?
I have a 4 gc2 battery bank that is fed by a Morningstar MPPT controller. I would really like to be plugged into shore power to run the refrigerator but if solar charging is better for the batteries I will just go that route.
Is there anyway to solar charge batteries and be plugged into shore power to run the refrigerator? Should I just plug into shore power and not worry about the onboard converter-charger and leave my solar charging on?
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RLS7201
Some Where
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Joined: 10/26/2002
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If both of your charge sources are 3 stage, it should make no difference which one you use. I have 410 watts of solar on my roof and my converter has been unplugged for almost a year. I see no need to pay the power & light company to charge my batteries when I have solar. I do plug in to shore power while at home so we can run the vacuum cleaner and 120 volt tools if necessary.
Richard
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Sandia Man
Rio Rancho, NM
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Joined: 08/09/2008
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We don't have solar, but we are always plugged in using our multi-stage Iota IQ4 converter to keep battery bank up and ready to go. Monitor battery fluids, but haven't had to add distilled water in over a year. We also incorporate the 40 amp Black & Decker periodically for equalization and additional desulphation routines. The solar option will be a future mod.
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Golden_HVAC
Fulltime, CA, USA
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Hi,
If you just park the RV and plug it into the shore power, the converter will keep battery voltage above 13 volts and the solar charger will not do anything to recharge the already full battery bank.
If you unplug the converter/charger, then the solar can keep the battery full, providing it is over 150 watts, and should be plugged back in to the receptacle about 2 days before leaving on a trip just to make sure the battery is full when you go.
Why leave the refrigerator on? If it used 300 watts per hour and runs 8 hours a day, that is 2.4 KW daily, or about 1/8 of a average utility bill for a house. So it works out to around $180 a year to run the refrigerator, when basically nothing is in it.
There is no advantage to running the refrigerator 24/7, and the heating element might break down after 4-5 years of use, and require replacement if possible, or might damage the boiler tubing it is mounted in when the heating element breaks. So if the heating element can not be easy to remove, then it is better to just run it on gas only for the rest of the RV's life.
Fred.
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smkettner
Southern California
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Joined: 03/21/2005
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Run solar and propane. Propane should cost same or less than the electric.
Otherwise you need a battery disconnect and have the solar still direct on the battery.
2001 F150 SuperCrew
2006 Keystone Springdale 249FWBHLS
675 watts solar
Send a PM if I missed something
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elkhornsun
Monterey
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smkettner wrote:Run solar and propane. Propane should cost same or less than the electric.
Otherwise you need a battery disconnect and have the solar still direct on the battery.
How do you figure that. I pay more than $4 a gallon for propane and I have to drive to a fill station with the tanks to get them refilled.
With 120v I pay less and all I need to do is run a 50' extension cord to the RV.
A 120v converter is not going to keep you batteries fully charged and healthy, especially if they are the flooded type. The solar systems MPPT controller will do a better job with your batteries but is not going to provide enough power for the DC operation of your fridge in any mode.
Ideal would be to isolate the solar output to the batteries by having a switch to kill power to the batteries from the converter when you are using shore power only to run the fridge. This is not an unusual modification and there are posts regarding doing it. Nice thing about having the solar system is that the option of disconnecting the converter from the batteries is a viable one.
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KJINTF
Montana
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Ezbagr
I assume you have a nice multistage converter, plug into shore power leave the solar connected and operational it will not hurt anything. The two systems play together very well.
Elkhorn - How is that power plant doing these days
I guess everyone pays a different amount for propane here my bulk rate is $1.80/gallon. If the OP has enough solar which I believe he does the solar will easily handle the refrig requirements, if the sun continues to shine.
Why disconnect the other charging device - they all play well together.
I disconnect (switch the breaker off) on my solar controller only when the rig is put away in the summer home / barn without shore power. All controllers draw a small amount of power when connected to the battery bank.
Thompson Falls Electronics
Always more projects than time
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smkettner
Southern California
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elkhornsun wrote:How do you figure that. I pay more than $4 a gallon for propane and I have to drive to a fill station with the tanks to get them refilled.
Above calc said $180 per year. That is 45 gallons of propane or about 30 lb bottle every two months. What is the fridge consumption of propane?
Regardless it is probably splitting hairs either way. I agree electric is more convenient. And I did offer a solution to use both the converter and solar.
* This post was
edited 06/18/12 02:35pm by smkettner *
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smkettner
Southern California
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elkhornsun wrote:A 120v converter is not going to keep you batteries fully charged and healthy, especially if they are the flooded type. The solar systems MPPT controller will do a better job with your batteries but is not going to provide enough power for the DC operation of your fridge in any mode.
I don't know the converter is that bad as some are quite good.
I think the solar would just be providing the 12v for the control circuit. My trailer uses about 500 milliamps with the fridge cycled on, propane detector, radio memory. I assume OP has a 120v-propane fridge not a 3-way.
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randallb
On the road
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Joined: 11/19/2007
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I have 2 Battery Tender Juniors. They are rated at .75 amps and do a great job. I pull in, hit the disconnects in the battery bay and plug the Jrs. in. I have yet to add water to the batteries before we hit the road. The BT Jrs spend most of their time with the green (fully charged light) on. There is no need to beat your batteries up with any more amperage than the JRs. supply when in storage.
Randy
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