Wanted to post this addendum to this voltage thread, as it seems to have 'generated' (groan) a lot of interest.
I finally straightened out all my charging issues. My original AGM batteries went bad after about 2.5 years, and I thought it was probably the Zamp controller overcharging them. Could have been other factors as well, including not-so-great AGM batteries to begin with, but I'll never know for sure. Replaced charge controller with Blue Sky SB3000i, and am adding Blue Sky's battery monitor. Everything so far is working good. Having more programming options on the Blue Sky controller is much better, IMO, than the fully automatic Zamp controller. Also added a battery temperature sensor, and getting ready to install another 100W solar panel to assist with my 160W panel on my roof. I went from 170ah AGMs to 230ah wet cells, and I need more power to recharge the batteries when I'm off the grid.
I did have one glitch a couple days ago, and wanted to mention it in case anyone else runs into the same issue. Initially, after I installed the new Blue Sky controller, everything worked fine. A few days ago I installed the battery temp sensor with truck outside, and batteries charging via my panels. When doing so I disconnected temporarily my positive terminal connections at the battery. Reconnected everything, put the camper in the garage and plugged it into shore power, went to bed. Keep in mind my batteries, at this point, are at float charge, 13.5V. Batteries fully charged. Next day looked inside at the controller and the voltage was 14.7V - bulk charge. For well over 10 hours. Left it alone for awhile, stayed right at 14.7V, high. Batteries boiling. Disconnected shore power (I have an Iota w/IQ4 converter) and put truck outside....charging almost immediately dropped to 14.5V (my absorption set level in the Blue Sky controller), and then eventually to 13.5, my float charge set point. So, everything's fine with my solar controller....what about the Iota? Put it back in garage, plug it in, go to bed. Next morning 14.7 AGAIN, all night. Looked online and there's a fault mode with the Iota if it senses a short circuit. When I also read my Blue Sky manual, it specifically states that if you disconnect the positive battery terminals, you MUST DISCONNECT THE PV (solar panel) POWER INPUT FIRST, otherwise you may cause a short circuit. Must be what happened, because I reset the Iota, and everything is fine now. So, just in case anyone else out there gets stuck in high voltage/bulk charge mode when plugging into shore power, the reason may be that the Iota had a fault. To reset the Iota is simple...you unplug from shore power, disconnect your positive battery terminal for at least 30 sec, plug in shore power, then reconnect positive terminal. Plugging into shore power before reconnecting prevents arcing. Also, the Iota converters are preset for Bulk = 14.7-14.8, Absorption = 14.2, Float = 13.5-13.6. Bulk can be up to 225 min/voltage set point, Absorption 480 min/voltage set point.