Battery and Solar woes

Qwazert wrote:
Long read, so grab a coffee...
Rockwood Mini-Lite 2306.
We’ve had this generic 100W flexible solar panel which has served us well for several years now. I hate drilling holes in the roof of my RV to pass wires through, so we simply toss the panel onto the roof when we arrive, and make connections to the controller and batteries. When not in use, the panel travels inside the RV between two mattresses, to keep it safe.
I coupled it with a 10Amp PWM controller that I had purchased from a different solar vendor a few years prior. This controller is adaptable for flooded or AGM batteries, but was set for flooded, as that is what we’ve always used. The controller has minimal user-interface (other than setting the battery type) and the only display you have is two green LED’s to indicate proper connection, and when the batteries are “fully charged” it will blink a green light to show “full”. As I mentioned, this setup has served us well for the past several years.
Last year, I needed to replace the batteries in the RV as they were over 6 years old and one of the terminals was starting to show deposits, meaning that gas was leaking through somewhere. I replaced them with a pair of Trojan T-105’s.
We do a mix of dry and full-hookup camping over the summer months, so either the solar panel or the on-board charger is keeping the batteries at the ready...according to the LED display on the controller or the one inside the RV.
Things started acting up on this last trip; after a couple of days of sunny skies, we had a few days of rain which meant the batteries wouldn’t get full power from the panel, but enough to keep the interior indicator showing 100%, and the green LED on the controller blinking. As soon as dusk fell, the indicator would show about 80% and would drop to 40% when running the water pump. This wasn’t normal, so I looked into the battery connections...definitely not perfect, but not bad enough to cause this. Cleaned them up but the results didn’t change. Luckily my buddy had a hygrometer, so I tested the individual cells...reading around 1230...only about 75% “fully charged” contrary to what my solar charge-controller was telling me.
The next few days gave us some more sun, so I monitored them carefully. According to the T-105 data sheet, the OCV of each battery when fully charged should be 6.37 yet even when I was able to achieve this reading through use of the solar panel...the hygrometer would still only indicate about 75 - 80 % charge. I use a high-end FLUKE multi-meter, in case there’s any concern about my tool-of-choice.
By contrast, my buddy also has the T-105 batteries and his OCV is around 6.9 and the hygrometer shows fully-charged.
When we arrived at the “full hookup” site the following week, the converter/charger in the RV went wild, as it struggled to charge the batteries. After about 4 hours with the fan running full blast, it finally quieted down and the batteries seemed to catch up and recuperate to full charge....or so I thought.
Checking them with the hygrometer again...only 80% charge even though the OCV was 6.6V now. By now, I’m starting to question whether this hygrometer is accurate, so my buddy takes it over to his rig and checks his batteries...100% charged.
At this point, I’m wondering if my converter/charger is defunct, so I pull out the manual and run through the troubleshooting guide. According to it, the output terminals should read 13.6 with the batteries disconnected...it only reads 13.2....half of which is 6.6...sound familiar?
I usually carry a spare car battery for Emergency use and even it shows between 1220 and 1230 on the hygrometer after being “charged” on the solar panel.
So it looks as if I have several issues at play here. One is the charger in the RV not putting out enough and the other being the charge controller from the solar panel also giving me bad intel.
I could use some advice/feedback....

I get scolded now and then for saying this but.....seeing you as an RV owner and somewhat do-it-yourselfer, I think it's beneficial to get over "hating drilling holes in your roof". There are so many great products to make this very do-able and leak free that I consider "not wanting to drill holes in the roof" a non issue now days. I think all of us on this forum are better craftsmen than the people that built our coaches and we have the same or more products at our disposal than the builders. I've modded my solar on the roof of my RV and just took my time doing everything I wanted to and did it carefully with zero issues and we've been in some serious rain and storms too. Saying all this becuase I now have a solar system that easily keeps up with the four 6v golf cart batteries. No tilting, no setting out panels, no following the sun.......and of course no shade for my campsites!...when possible. I have this easy solar life 'cause I got over punching holes in my roof.