I have a Xantrex SW 3012 only a year old and believe it is the problem, but checking to see if anyone has a different idea. I went into the coach yesterday and noticed the monitor showed "absorption" thought maybe a temporary power outage caused it to cycle. Went out this morning and it was on "bulk" charging at 14.4 volts. Left for a job and came back 3 hours later and still on "bulk" went to the unit and gave a gentle persuasive percussion to it. Went back in the coach and it showed "absorption" 14.4 volts a minute later it went to "float" Came back later to see if all was well and it is back on "bulk" I don't want to cook the AGM's so I will shut it down for now.
After checking all the mechanical connections, go online to check your AGM batteries recommended float voltage. Every manufacturer will have this information, either online or by calling. With this info plus age of the batteries, call your dealer or Zantrex and describe the problem and when you first noticed it.
Most chargers have either switches or software to control the charging voltages. Values are configured during installation.
Smart to shut it down until you have the problem isolated. AGMs are expensive, especially when you have several onboard.
Pierce
Update it is now on float at 13.6 volts. I will see how long it stays on float.
Not sure which control panel but had similar issues with the Victron until I updated software. As you work the other issues you may want to do a reboot of the panel.
Check the 120 VAC connections from shore power to inverter/charger. If the inverter/charger looses 120 VAC even momentarily, it starts the process again in bulk mode.
If you have a way to wire it, hook up a digital electric clock or other device that will tell you if power went out-- even momentarily.
With our old inverter, we used the microwave oven clock for that purpose. Our new Magnum inverter switches modes so fast that nothing in the coach will register a power cut.
I wonder if something like this would detect the momentary power outage?
Amazon.com: POWER FAIL LIGHT W/ALARM by RELIANCE CONTROLS MfrPartNo THP207M:... (http://www.amazon.com/POWER-RELIANCE-CONTROLS-MfrPartNo-THP207M/dp/B018A30T8Q)
Failed Circuit Alarm (New Style) - Household Alarms And Detectors - Amazon.com (http://www.amazon.com/Failed-Circuit-Alarm-New-Style/dp/B0077Q9NC6/ref=pd_lpo_469_tr_t_3?_encoding=UTF8&psc=1&refRID=MZJJZ54YNV1TAKJ1NHTK)
The power comes from a Y that powers my '99 and the '81, the inverter in the '81 is the trace 4012 it will go to bulk if there is a power drop of any length. It is staying on float. The fact that hitting the sw3012 made it immediately go to absorption then a minute later go to float is why I am going to put in my old SW3000 and see if the problem goes away. The only other thing would be if the transfer switch could drop out. I can't think of any reason it would though. It is back to jumping between bulk and absorption again at this time.
The suggestion to reboot the panel will be my last try before switching the inverters. The only way I can see to reboot is to cut all power to the inverter and the panel.