My 2012 Hawk has a 110 fridge and I got it with the 85 watt factory solar. It never seemed to charge well. Adding to the IOTA a Q4 plug vastly improved charging when plugged in to 110. Traveling down the road for hours or leaving it parked in the sun didn't give it the charging it needed in the winter let alone in the summer. First I installed larger batteries, that helped a bit as I could stay out a day longer but it added a problem of taking even longer to get back to fully charged. I next installed a Tri-metric battery monitor which was a great help as now I could see exactly how each component effected my charging. The 85 watt solar panel only put out enough power to just run the fridge but not enough to run the fridge and charge the batteries. I knew that I needed a larger solar array, I ended up with a 160 watt grape solar panel and a SunSaver MPPT. A PWM controller probably would have been fine. This only added 9 pounds more to my roof.
The charging from the truck was what I call weak at best, I was only getting to the batteries 13 or 14 AMPs if the fridge was running and it usually was during the summer. At 13 amps I'm only getting 52amp into the battery after 4 hours of driving, NOT ENOUGH. I wondered if it was my Alternator or voltage regulator or the wire gauge from my truck to the camper? To see if it was the truck I took a 4 gauge jumper cable and hooked the truck battery to the shunt on the Tri-metric and the camper battery positive. WOW 55 AMPs. From this I learned that my truck was putting all the juice I needed, I just needed a better system to get it into the camper batteries.
I bought 25 feet each of a red and black 6 gauge wire. I also bought a hydraulic wire crimping tool at Harbor Freight, you must have good connections. On each end of the positive wire I put in Maxi Fuse Holders which came wired into 6 gauge wire and 60 AMP Maxi fuses. For plugging the camper and truck together I used a Marinco 12VCP6 trolling receptacle and plug That was the only trolling plug that could take a wire as large as 6 gauge (could have used Anderson plug). I then rewired the plug to camper with the same 6 gauge wire.
When I thought about how I was going to control the switching on and off the power it made my head hurt. Should I put a solenoid in the engine compartment with a switch in the cab, should I put in a perko switch in the camper? When I looked at the paper work for the Sure Power battery separator I found that not only was the separator rated to handle 100Amps but also the installation said to use 6 gauge wire for wire lengths from 10 to 20 feet. No wonder the 10 gauge wire from the factory wasn't giving the charge I thought I should be getting. So I went ahead and used the Sure power separator with 6 guage wire going to the battery. One note here is be sure to leave the factory circuit breaker protecting the wire to your fuse box.
After doing the solar upgrade and the rewiring of the truck to camper my system now works great. I haven't seen my system under 82% charged and a charged battery is a happy battery. One thing to note here is that after a few minutes of charging the amps going into my batteries drops(as expected) I get about 28 amps charging after 5 minutes.