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kpoinville

Adding solar to existing 12 v system in RV

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My wife and I recently purchased a 1997 Coachmen Mirada.  I plan to install the following:

  • 2 Renogy 100w solar panels,
  • a 40 amp Renogy Rover solar charge controller,
  • 2 100 ah 12 volt Renogy  gel deep cycle batteries, which will be wired in parallel.  

I have purchased a Renogy 2000 w pure sine converter, but I am not certain that I will install it.

I have already removed the original house battery and replaced it with the two gel batteries.  My questions are probably stupid, but here we go:  

My understanding is that the controller will be connected to the new battery bank and the panels get connected to the charge controller.  I plan to add a fuse between the solar charge controller and the battery bank. 

(1) Am I correct that the wires from the existing 12 v power center (that were originally connected to the house battery) should be connected to the new battery bank?  

(2) Will I still be able to plug into shore power when needed to run the AC?

(3) I assume that the original 12 v system  (as built by Coachmen) has an automatic transfer switch for when the RV is connected to shore power.  If I connect to shore power, will that transfer switch cause my battery bank to be recharged?  (I don't think that I will need that capability, but I am just curious about whether I am thinking of how the pieces fit together correctly.  Does that sound right?

Any insight would be appreciated.

 

Ken O'Brien

Louisville, KY

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Ken - Welcome to the forum. Glad that you're here and adding to the discussion.

We did something similar, so I'll try and hit your questions and explain how we did this...

1) You've already replaced the previous house battery bank with the new. Just connect them to the existing 12v power center like they were before. One thing that you'll have to verify is the charging voltages from your existing battery charger/converter. It was probably set up for flooded cell batteries, and your new Gel batteries might require different voltage levels for charging. You'll either need the manual for your existing charger/converter or a multi-meter to test the output manually. Consult the info from your new gel batteries to determine what charging voltage the manufacture recommends for the various stages of charging.

2) Shouldn't be affected by adding solar or changing batteries at all.

3) ATS (automatic transfer switch) usually is used to switch the 120v input from generator to shore power as required. Doesn't directly affect the 12v system, other than when there is 120v power available it will be used to power your battery charger/converter.

If you are not getting battery charging from your current setup, you might check to see that the charger/converter is plugged in and that the proper circuit breaker is on.

Now, about the solar...

We added 560 watts of solar through a solar charge controller. The charge controller is connected to our house battery system parallel to the 120v charger/converter. In other words, we connected the positive output from the solar charge controller to the positive end of the battery bank, and we connected the negative output to the negative end of the battery bank. These are the same places that our 120v charger/converter connects. There is a manual-reset circuit breaker in between (in place of a fuse) which I can use to separate the systems if necessary by tripping the breaker. When solar is providing power, it piggy backs with the 120v charger/converter.

The solar panels connect to our solar charge controller through a battery switch on the positive lead. This allows us to disconnect them from the charge controller for times we need to fully power down the system. Remember that the solar panels themselves do not turn off - if they are receiving light they are making power.

You'll need to configure the output settings of the charge controller to provide the appropriate voltage levels for your gel batteries, just like with the 120v charger/converter. Manual should show you how.

Couple of other notes...

Don't skimp on wire size. The ability of a solar system to send power to the batteries is limited by the wiring being used. If you plan to add more solar later on, go ahead and install the wire size you'll need for the total that will be installed. Otherwise you'll have to run wiring to the roof again later on. The 12v wiring size between the panels and the charge controller will depend on the amperage being carried more than the voltage. We have 6 panels total, which are configured in a parallel/series configuration so that we have higher voltage but lower amperage. Allowed for smaller wiring. However, the wiring between our charge controller and the battery bank is quite heavy, since it needs to carry 30+ amps DC.

We installed a 2000w inverter when I did the install. Initially I connected it to three dedicated outlets inside the coach so that we could have 120v available when dry camping. Since then I've done some expansion of that with additional connections as I've seen need.

You only have 200 Ah of house batteries right now, which doesn't give you much capacity for using that 2000w inverter. That said, you might as well at least get it mounted and installed near the batteries while you're in there working. You can add to that later on, but at least you'll have the outlets on the inverter available to plug into when needed.

Hope all this helps. Feel free to ask more questions if you need.

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Welcome to the forum.

 

4 hours ago, kpoinville said:

(1) Am I correct that the wires from the existing 12 v power center (that were originally connected to the house battery) should be connected to the new battery bank? 

Yes

 

4 hours ago, kpoinville said:

I have purchased a Renogy 2000 w pure sine converter, but I am not certain that I will install it.

Why not?

4 hours ago, kpoinville said:

(2) Will I still be able to plug into shore power when needed to run the AC?

Yes that or run the generator. How big is the generator? 

 

4 hours ago, kpoinville said:

(3) I assume that the original 12 v system  (as built by Coachmen) has an automatic transfer switch for when the RV is connected to shore power.  If I connect to shore power, will that transfer switch cause my battery bank to be recharged?  (I don't think that I will need that capability, but I am just curious about whether I am thinking of how the pieces fit together correctly.  Does that sound right?

The automatic transfer switch has nothing to do with charging the batteries. All it does is save you from manually selecting the power source. I had a 78 Executive, if you wanted shore power you plug the cord into the shore pedestal outlet. If you wanted power from the generator you manually plug the cord into the generator. 

Yes you will need the ability to charge your batteries from shore power and the generator.

Bill

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I believe the OP said that he had now replaced his original house batteries with gell cells, not AGM, which is good since the solar system batteries are also gel cell. Please make sure that the inverter/charger is programmed for gel cell batteries. These batteries will all be charged by whatever is charging them now, only difference is now that you will have the additional 200 watts of solar power to help maintain charge on the now 4 battery bank, + the ability to use that 200 watts in the presence of sunlight when no other outside source for charging them are present. What AH are the new gell cells that replaced the original flooded cell batteries and what AH for the new add ons?

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1 hour ago, kaypsmith said:

I believe the OP said that he had now replaced his original house batteries, not AGM, which is good since the solar system batteries are also gel cell. Please make sure that the inverter/charger is programmed for gel cell batteries. These batteries will all be charged by whatever is charging them now, only difference is now that you will have the additional 200 watts of solar power to help maintain charge on the now 4 battery bank, + the ability to use that 200 watts in the presence of sunlight when no other outside source for charging them are present. What AH are the new gell cells that replaced the original flooded cell batteries and what AH for the new add ons?

Thanks for pointing that out. My earlier post has been edited to reflect that.

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I want to thank each of you for your response to my inquiry.  This forum has been so incredibly helpful to me.  The coach is at a local service center today some engine work, but I will continue the solar install this weekend.   I am really looking forward to it!   Thanks!

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