Electrical problem

[Shadow Catcher]

Strange problem. teardrop is back from major rebuild, and a good bit of that was electrical. We have a 185W high voltage panel that typically puts out 35+ volts at the Morningstar Sun Saver MPPT controller. I have the remote meter which tells me the battery voltage and the solar panel voltage and the reading is 9V. I use my VOM multimeter and sure enough I am getting 9V at the controller I disconnect the Anderson Power Pole and am reading 35V coming from the solar panel, clean contacts etc still getting 9V at the controller when I plug it back together. Cut the wire removing the Power Poles (thinking that was thee problem) and wire it to the controller, the voltage when connected and under load is 9V. Pulled out a new (spare) controller. same problem! Connected a 25W panel I use for maintaining the battery. Everything works fine and read 17.8V at the controller.
I am trying to figure out likely cause.

[John61CT]

Post specs for both panel and SC.

Have you called MS?

[bdosborn]

what's the voltage at your battery? Is the 9V coming at the output terminals of the MS or is it at the PV input terminals? Is the panel in sunlight when you get 9V?

Bruce

[Trebor English]

The solar panel has a short circuit current rating, Isc. 185 watts divided by 35 volts gets you to about 5 amps. Put an amp meter between plus and minus with the panel in good sun. If you don't get close to the Isc rating there is a problem with the panel. A completely shaded cell will kill the output. A high resistance somewhere will dramatically reduce the current.

[pchast]

Have you tested your battery after disconnecting it? Is it 12+ volts?
If you connect a known 12 volt battery to that system instead,
does that controller auto correct to 12v+

[Shadow Catcher]

what's the voltage at your battery? Is the 9V coming at the output terminals of the MS or is it at the PV input terminals? Is the panel in sunlight when you get 9V?

Bruce

The battery is new and fully charged. The 9V reading is at the input to the solar controller the second the solar panel connects. My current thinking is there is a weak connection someplace between the controller and the panel. The behavior is the same with each controller.

[bdosborn]

Maybe take a temporary cable and connect the panel directly to the controller and see what you get?

Bruce

[low277]

Maybe take a temporary cable and connect the panel directly to the controller and see what you get?

Bruce

X2 that should help narrow it down quickly.

[Shadow Catcher]

It is going back in tomorrow, to fix a couple of problems, i.e. support for the gas struts holding the galley hatch were set too high, and replacing the rear cupboard doors, one was seriously damaged by a leak. I replaced the reading lights, one switch broke.