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Complete newbie here, so go easy on me please. I was given a couple of Jinko JKM315P-72 315w panels by a buddy. I bought a MPPT 100/30 and wanted to test everything before I installed on my RV. I hooked up to my Optima battery on my Jeep, and discharged the battery a bit to see if it would charge. What on Earth am I doing wrong? I tried using a really discharged Interstate flooded battery (10v) to see if it didn't like the Optima, with the same results. Sunny and clear out. 
Looking at the specs of the panel and the information showing on your MPPT, there is either a problem with the panels or, the panel placement. The MPPT is doing its job--taking 41.5v 0.2A to 12v 0.8A--it just isn't getting very much current to begin with.
Placement of the panel is very important. Even in full sun, the angel of the panel is significant. If you can, do your testing when sun is at its highest point, and lay them flat on the ground. I would test each panel separately, looking for a difference between the two in voltage or current.
Panels do degrade slightly over time, so depending on how old these are they may not put only either listed power even if nothing is wrong.
I tested both panels independently, and laid them directly on the ground, stood them up, 45* angle, etc, in direct 85* Southern UT desert sun. Same results. Any other ideas?
I wish everyone documented their problems with as much detail as you have. Thanks.
With the output readings on the MPPT, most likely causes are
Faulty connections/fuse between MPPT and battery
Undersized cables between MPPT and battery
Undersized cables between panels and mppt
MPPT fuse
Lack of light (as stated already)
Trying to charge a lithium battery with lead acid settings. Are your batteries spiral cell? If not, pick the correct battery type, or set a custom type using battery makers values.
Faulty MPPT.
Here is some more info
- 10 gauge from panel to MPPT (brand new cables).
- 8 gauge from MPPT to battery (fuse/breaker removed for troubleshooting purposes)
It's an Optima Red Top battery, a spiral cell battery. It's cloudy out today, so will have to play with it some more when the sun pops out. I will check the fuse on the MPPT, thanks!
I changed from preset agm spiral to preset victron deep discharge and then back to agm spiral and it started doing *something*. However the numbers don’t match what my meter shows. Cloudy day today, of course. 
Just wanted to point out that your multimeter is in current mode in the above photo. That means it’s essentially shorting out the PV panel(s) and taking 1.248A to do it.
When the MPPT is working correctly and sun is shining, it constantly adjusts the current being taken, which in turn affects the voltage across the panels, to get the maximum power output. Power is the product of voltage x current.
Those panels have an Isc of 9.01A so if you’re only getting 1.2A and the sun was strong, then that’s indicative of faulty PV panels to me. Might be worth trying that again with MPPT disconnected. Your meter is rated at 10A so should be able to handle it for a short time but take care.
Edit: just noticed, your red meter lead isn’t in the 10A socket so try it in there if doing an Isc test.
You're going to have to tie it down to panels (as in both faulty, they don't look new) or MPPT. I'd guess MPPT. Which means talking to your dealer.
