Northeast Doing something wrong despite 6V AGMs

[AirstreamCSH]

Hoping the forum can help us figure out why our 2016 FC FB25 only lasted one night boondocking.
We keep the Lifeline GPL-4CT twin 6V AGM batteries connected to the Progressive PD4655 trailer charger using a 30a hookup at home while stored.

Unhitched a fully charged trailer at 3pm at the balloon rally in Syracuse. Nothing special about electric use that day and evening; ceiling fans, LED lights at night and propane water heater for an hour. The following morning, we had 12.4 volts and the 180w Zamp suitcase in full sun charged the batteries to 12.9v by mid morning. During the day, the fans were going and we didn’t really use the equipment except for 15min of the stove overhead fan and a 30min burst of the furnace that second night. Before bed the batteries read 12.4. The second morning the factory monitor in our 2016 FC read 11.9 and dropped to 11.6 when the furnace was turned on in 50-degrees

We let batteries drop to 11.3 before I hooked up the truck umbilical and that stabilized voltage at 11.9 until sunrise when the Zamp took it to 12.1 and I disconnected the trailer from the truck again. Noticed the fridge was reading 36-dg so dropped those settings down from 4 to 3 around the time we turned on the furnace this AM.

Two hours of the solar charger and 30 min of the furnace later, the voltage reads 12.4.
For background to understand my focus on these numbers, AM Solar told me via email that full discharge is 10.5 and max charge is 12.9 so it should go go lower than 50% for long life meaning charge as it approaches 11.9.

Based on the above, can any knowledgeable members here see what we may be doing wrong?
Is it possible the Zamp drew down the battery somehow while connected at night? Doesn’t seem likely.
Wondering if we’ve done damage to these 18-mo old batteries by keeping the trailer plugged in while at home.
Simply confused.

Thank You

[Al and Missy]

First, the voltage numbers don't mean much as long as the battery is charging or is being used. The numbers should be read after about an hour or so of no charging or nothing being used. So I doubt that you have damaged the batteries.


Check your fridge, probably in the top of the freezer door trim, for a humidity control switch and make sure it is off. The switch controls heat strips in the door to keep humidity from condensing on the door seals. If you don't have the switch (some newer trailers/fridges don't) the heat strips run all the time. Folks have modified the fridge to add a switch or disconnected them. IIRC the wire for the heaters without the switch comes off the supply side of the light that comes on when the door opens.


Another fridge switch that affects power consumption is the low ambient switch. When it is on, the light in the fridge stays on all the time. If you have that switch, make sure it is off.


I keep thinking of things.....the 4655 is, IMO, a good 4-stage charger and should not overcharge the batteries.


Al