Solar Controller Problems

acmedave said:

But how about this. If I disconnect each of the 3 pairs of wires from the controller and test them with a multi meter it would seem to me the battery wires would show 12+ volts, the PV pair should show about 27V when the sun is on them and I would expect the load to show no voltage once disconnected from the controller.

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Yes, those assumptions make sense to me.

acmedave said:

I would also think that when the load was turned off in the app that the lights and fan would turn off as well.

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Me too, hence the confusion all around.

What is the load current (in the app) when you turn various devices on? That may tell you what is actually connected to the load terminals.

The other option is just to beep it out. Disconnect the load wire from the controller and use the continuity setting on a multimeter to see where the wires go.

This may all be a red herring, but something doesn't seem quite right here.

I’m thankful for everyone’s input and I do agree something doesn’t seem quite right.

Today I disconnected the wire pairs and did a voltage check.
The battery pair had a reading of 0V
The PV pair read up to 27V, varied with solar intensity
The load pair read 12.95V

With the battery and load wires disconnected lights, fan, etc. still worked. Wasn’t expecting that.

I reconnected everything the way it was.
When I turn anything with sufficient draw on I get a current reading in the app that reflects the load.

But is seems the battery and load wires are on the wrong terminals.
Is it safe to swap them out?

Assuming the measurements were on the wires, I would agree that it sounds like battery and load are reversed.

It should be safe to swap them, but I would feel better about it if you new for sure. Can you at least beep out the battery wires and verify the wires that were going to load are actually directly wired to the battery?

By beeping them out i’m thinking you mean I should disconnect the wires in question from both the battery and the controller and do a continuity test?

Also the suspect wires are red and black at the battery but black and white at the controller. So somewhere at least on of them is not continuous.

acmedave said:

By beeping them out i’m thinking you mean I should disconnect the wires in question from both the battery and the controller and do a continuity test?

Also the suspect wires are red and black at the battery but black and white at the controller. So somewhere at least on of them is not continuous.

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Yes, do a continuity test. Something is wired incorrectly here, and it would be better to have a firm idea of what is going on before attempting to fix it.

Did a continuity test of the battery wires and load wires. Turns out the battery positive wire from the battery to the controller has a fuse in it at the battery that was burned out. Once a new fuse was installed the disconnected battery wires at the controller had the same voltage as the battery.

Could this have been causing solar controller failure?

The load positive wire is connected to the fuse box and the fuse box has power whether the load positive was connected at the controller or not.

So I dont understand how the system worked at all unless the battery was being charged through the load terminals which seem to be also connected to the battery independently of the connection at the controller. Should I consider this a problem? I don’t really see where I would have a need to disconnect the load via the app.

Are you the original owner?

If it was my system I would have the output of the controller only going to the battery. If the controller is not only seeing the battery voltage, then the controller is working hard to adjust to charge your battery.

If by chance the previous owner did not know there is a fuse in the controller to battery and it stopped working, then perhaps it was easy to bypass the proper wire and hot-wire to the fuse box thinking it would charge the battery.

Maybe show a quick wire diagram as to how it is wired. (I see things better than reading them)

I am the original owner. And have been plagued by solar controller failures. Unfortunately I don’t have a wiring diagram. But I am wondering if you’re suggesting just doing away with the wires at the load terminal of the controller so the controller is ‘only’ connected to the PV and battery.

While the load terminals of the controller go to the load at the fuse box they are connected to a hot wire coming from the kill switch. So it seems the load circuit is fed from 2 sources. Unless the wire from the fuse box to the controller is just to get a load reading. Sorry if this is a confusing explanation.

Good sleuthing. This could explain your issue - with the battery fuse blown, all the charge current was flowing through the load terminals - which means it was likely not being sensed by the MPPT controller correctly, which could certainly cause issues. Before the fuse blew, you had a path through the load terminals from the main 12V bus back to the battery. If you charge from either the truck or the on board converter, this could lead to reverse current to the battery though the load terminals, which definitely has the potential to cause damage.

The easy way to fix this would be to disconnect the load terminals from the controller. If you want to still use the load terminals, you need to find the other path by which the fuse block is getting power and disconnect that, so the fuse block is only powered through the load terminals. You also want to make sure that any other charge sources (truck alternator, converter) are connected directly to the battery and not the fuse block.

Note you can only draw 15A or whatever you controller is rated for from the load terminals. If you have higher current loads (eg and inverter) this won't work.

PS it sounds like FWC owes overland solar a few charge controllers. As mentioned earlier wiring is not FWC (or ATCs) strong point.

Thanks Rando. I never paid much attention to "Load" wires option nor bothered to use them. Good to hear more how they should work.

Funny thing is. Now that I’ve replaced the fuse at the battery, and left everything else the same I no longer get a ‘current’ reading in the battery or load output section of the app. Confused!

acmedave said:

Funny thing is. Now that I’ve replaced the fuse at the battery, and left everything else the same I no longer get a ‘current’ reading in the battery or load output section of the app. Confused!

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Like rando suggested, you need to simplify so you can troubleshoot more effectively. That means not using the load connectors for now, and then opening circuits/connections until the fuse block loses power.

rando said:

The easy way to fix this would be to disconnect the load terminals from the controller. If you want to still use the load terminals, you need to find the other path by which the fuse block is getting power and disconnect that, so the fuse block is only powered through the load terminals. You also want to make sure that any other charge sources (truck alternator, converter) are connected directly to the battery and not the fuse block.

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Seems the fuse block may be intended to receive power directly from the battery and converter? Perhaps the positive wire from the load terminal of the controller to the fuse block should never have been installed,

This from the FWC Operation Manual:
When the camper is plugged into 120v shore power or a generator (electricity), the silver 12v master switch can be in either the “IN” or “OUT” position to operate the appliances in your camper. However, if you would like to have your camper battery(s) recharge from the 120V shore power electricity, the silver must be pulled “OUT” to allow for recharging of the auxiliary battery through the 30amp IOTA power converter

Not sure yet why the wire is going to the fuse block and why FWC wires it that way in the first place. Seems that once the fuse blew it only caused you grief and labor.

I would remove it, tape the end and see how it works from there on.

acmedave said:

Seems the fuse block may be intended to receive power directly from the battery and converter? Perhaps the positive wire from the load terminal of the controller to the fuse block should never have been installed,

This from the FWC Operation Manual:
When the camper is plugged into 120v shore power or a generator (electricity), the silver 12v master switch can be in either the “IN” or “OUT” position to operate the appliances in your camper. However, if you would like to have your camper battery(s) recharge from the 120V shore power electricity, the silver must be pulled “OUT” to allow for recharging of the auxiliary battery through the 30amp IOTA power converter

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OK, having never owned a built model of FWC, just shells, this is my first time hearing that whole quote. Based on that, I think that this pic depicts what it says:




Does this look like what you expected? If this is correct, then we can make some sense of what you are observing. And if it is wired right, then all other stock campers should exhibit the same behavior.

Vic Harder said:

Does this look like what you expected? If this is correct, then we can make some sense of what you are observing. And if it is wired right, then all other stock campers should exhibit the same behavior.

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Yeah, I can’t follow all the wires end to end to be sure there are no other connections. But your diagram reflects what I find.

acmedave said:

Yeah, I can’t follow all the wires end to end to be sure there are no other connections. But your diagram reflects what I find.

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OK, so then what do we know? If the diagram is accurate:

1) With the camper on AC power, you will always have power inside the camper, no matter what position the kill switch is in. Is that the case for you? Is that the case for all FWC from the factory?

2) If you unplug the AC power, and leave the kill switch OFF (is that pushed in?) then if the LOAD setting in the MPPT is set to OFF, then you should have no power in the camper. Is that the case for you? Is that the case for all FWC from the factory?

3) With kill switch OFF and the LOAD setting in the MPPT set to ON, you should have power, even with no sunshine falling on the solar panels, you will have power because it goes from the battery through the MPPT to the LOAD terminals. (That sounds goofy to me.... because it means the KILL switch doesn't kill all power). (Same questions).

4) Per your troubleshooting above, if you disconnect your LOAD terminals, and the KILL switch is OFF and AC is not plugged in, you should have NO power in the camper. (Same questions)

Any other testing you can report on would be good.