Help Please-I thought I had my solar set up correctly

I have an EPever 40 SC, (2) 100watt HQST panels, works great when its the only thing hooked to the battery, but when I add the main power from the truck camper to the battery and an accessory cable, it doesn't work any more. Any ideas? I have a 30AMP fuse from the panels to the charge controller, a 50AMP from the SC to the battery. Nothing is tripped. I did notice when I attached the MC4 connectors the polarity on the wires reversed Blue was supposed to be Positive but when I connected the White wire, the indicators on the SC showed correct.

the plot thickens.....I bought a separate terminal and connected the _+ and _ on the new terminal......now with both the + and - connected, the SC MT50 flashes welcome...over and over....if I disconnect the negative, the SC stops flashing welcome but it says the panels are not producing power, and shows 24v instead of the 15v it used to show....this is crazy.

I'm not entirely clear on this, but did you have your charge controller connected to the panels at any time that it was not connected to the battery?

Yes, I put in a switch so I could turn the panels off if I had to work on it. So when I moved the wires around the panels were off.

Liz@lowcountry said:

Yes, I put in a switch so I could turn the panels off if I had to work on it. So when I moved the wires around the panels were off.

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So I guess since they were off, they were not connected to the battery...?

When you say it doesn't work anymore. Is it just turning off?

I'm suspecting you may have a bad battery or bad connections to the battery. I'm thinking the load is drawing all power and shutting down SCC

Check thosr cables going into the charge controller. They can seem well connected when they aren't. Give them a good tug.

The battery is new, the indicator in the truck camper is saying the level is green, so I disconnected everything, attached the battery to the solar controller to see if that reset the voltage. With positive and negative connected, it flashes welcome......never gets past that....

New Mexico Will said:

Check thosr cables going into the charge controller. They can seem well connected when they aren't. Give them a good tug.

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thank you

So, I took everything a part and unplugged the controller, same problem,

The truck camper had a pre wire SAE connector so I got renogy SAE to MC4 connectors and Y branch connectors along with a no name 10 ft red and black MC4 extension cable. I have heard Renogy cables have reversed polarity? Is it possible my no name connector has normal polarity and having the two connectors connected has caused my issue? I am shocked there is not an electrical standard that forces interconnected connectors to have the same polarity.

Thoughts?