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RVing message boards => Tech Talk => Solar => Topic started by: BigSkyTrailerGuy on September 06, 2017, 10:42:08 AM

Title: Yet another ignorant solar question:
Post by: BigSkyTrailerGuy on September 06, 2017, 10:42:08 AM

When connecting the controller to the batteries, do I need to disconnect the cables in from the RV's converter/charger? 

thanks, you Forum folks have been patient.
Title: Re: Yet another ignorant solar question:
Post by: halfwright on September 06, 2017, 11:00:15 AM
If you have the inverter wired directly into the 120 volt circuit in the trailer, yes.  The charger will detect 120 and try to charge the batteries with 12 volts. This sets up a loop.
Title: Re: Yet another ignorant solar question:
Post by: BigSkyTrailerGuy on September 06, 2017, 11:26:06 AM
To clarify, I'm talking about while boondocking.... no shore power.
Title: Re: Yet another ignorant solar question:
Post by: halfwright on September 06, 2017, 11:33:35 AM
Are you using solar for just 12 volt? If so, it is not necessary to disconnect.
Title: Re: Yet another ignorant solar question:
Post by: Lou Schneider on September 06, 2017, 11:50:02 AM
When connecting the controller to the batteries, do I need to disconnect the cables in from the RV's converter/charger? 

No, you don't.  The RV's converter/charger will just sit there doing nothing, like it does whenever you're not feeding 120 VAC to it.

When you are connected to 120 VAC, both the converter and solar will charge your batteries.  No problem, whichever source has the higher voltage will take over and the other one will back off automatically.

The situation you want to avoid is if you install an inverter.  The converter/charger must NOT be powered by the output of the inverter.  This sets up a perpetual motion loop that wastes a lot of power - the inverter draws power from the batteries and converts it to 120 volts, the converter takes the 120 volts, converts it back to 12 volts and feeds it back into the batteries, where the inverter draws it out again.


Title: Re: Yet another ignorant solar question:
Post by: John From Detroit on September 06, 2017, 04:40:21 PM
NO. I don't know where that one poster got his LOOP from, but there is no problem

IN fact those who have Solar, in addiotion to a converter and/or Inverter/charger Well.

I run both a coverter and inverter/charger (once I get it fixed,, Old age issue, ) in parallel, along with the engine alternator.. With DC systems you can have multiple "Sources" in parallel. as many as you want.. The only "Danger" is that the one with the highest voltage at the moment may do most all the work while the others sit there

Thus when on shore power at night the converter (or inverter/charger) will keep the batteries charged but if SHORE POWER is lost the batteries SUPPLY power till the sun comes up then the SOLAR charges.

IN the day both Solar and Shore may charge depending on the voltage settings.. Or one may shut down under the controller when it "Sees" the other. In either case NO damage happens.

Think of 5 people all pushing on the same stuck car.> They all work together

You might want to stop reading this post now...
But in an AC system they PUsh/pull/push/pull   and if say 2 are pushing when 3 are pulling.. Well that don't work well.
Title: Re: Yet another ignorant solar question:
Post by: kdbgoat on September 06, 2017, 04:57:00 PM
This may help you:

http://www.jackdanmayer.com/rv_electrical_and_solar.htm

Specifically this:

http://www.jackdanmayer.com/RV_Electrical_System_Schematic.html

Title: Re: Yet another ignorant solar question:
Post by: kdbgoat on September 06, 2017, 04:59:49 PM
And this:

http://www.jackdanmayer.com/Inverters_Chargers_Converters.html

Read the "What about my converter?" paragraphs.