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kipwill said:

Thank you both for your comments.  We are not hooked up to TV via 7-wire at present.

As for the battery switch, we have been unsure when to turn it off (red).  It sounds like any time we aren't using the camper and won't have solar gain we should turn it off, but leave it on (green) if our solar panels will be helping keep the battery charged.  Is that accurate?

Marceline, I did set the solar controller to lithium when I installed the new battery last year.

Li Time, the lithium battery manufacturer, has an app that measures battery charge via BlueTooth.  I've read it is much more accurate than the NuCamp wall monitor, especially for a lithium battery.  At present, after being on shore power for over 4 hours, the app tells me we are at 99% SOC.

So that still leaves me with the question of why the battery became so depleted.  Fridge is off, not using heater or even LED lights, not connected to tow vehicle.  What would you suggest?

I confess that I don't remember what the converter output is, but 'm skeptical that your battery is really at 99% after four hours plugged into shore power.

kipwill said:

In the past we had occasional problems keeping the battery strong in our TAB, but after replacing the original lead/acid battery with a LiTime lithium battery last year we've been able to camp without shore power for about 3 days and have our fridge, etc. still operate.  (We also have 2 small solar panels on the roof.)

But this week, just as we are about to leave for a long trip, we noticed the CO/propane monitor was flashing and buzzing.  Based on comments previously posted in this forum, a low battery seemed like a likely cause.  So I plugged into shore power overnight, and everything seemed normal the next day, even after disconnecting shore power.

First, you should turn off the battery switch when your camper is parked and not in use, especially if your solar panels are covered. Second, plugging into shore power overnight may not have been sufficient to fully recharge a completely depleted battery. If you don't have a lithium-compatible converter in your trailer, you may need to get an external charger that is capable fully charging a lithium battery. You don't say the year of your T@B but the original converters can only charge a lithium battery to about 80-85%. Or you need to get your trailer into full sun for a few days. Be sure that your solar controller is set for a lithium battery.

I began checking battery level on our wall monitor after that, however, and noticed that the battery reading dropped from 13.0 to 11.9 over about 2 days, with no major users (fridge, heat, etc.) turned on.  Then when I checked it this morning, the monitor wouldn't even light up when I pressed the battery button, and the CO/propane monitor was again flashing alarms.  I once again connected to shore power at our house, and the battery measured 13.6.  I disconnected shore power after a few minutes to check battery level, and got a 13.0 reading without shore power.  I now have shore power hooked up again, just to make sure we have the battery fully charged.

My problem is that I can't figure out what I can do to be allow us to start our trip and be able to count on the battery retaining a strong charge.  (BTW, the on/off switch near the battery on the tongue is turned to green.)

Does anyone have a suggested remedy?

Thanks in advance,
-Will

13.0v is actually a very low voltage level for a lithium battery, so your battery wasn't fully charged to begin with. The monitor on the wall is barely reliable for lead acid batteries and is not reliable at all for a lithium battery. If you do a lot of off-the-grid camping, I recommend you install a Victron SmartShunt, which measures amps going in and out of a battery. The measure of 13.6v when you connected to shore power isn't a measure of the battery level, it reflects the current going into the battery for the shore power.
My recommendation to get you on your way for your trip: Buy a lithium-compatible battery external charger and connect it to your battery to get it fully charged. If you have a 100aH battery and you buy a charger that outputs 10A you will need to leave it plugged in for at least 10-12 hours. If you buy a charger that outputs 5A you will need to leave it plugged in twice as long.

Yes these Speedwire pressfit 120v receptacles are scary.  Everyone should rip them out and and replace with screw terminal duplex or gfi outlets.  Not backstab type either.  Below are relocated outlets for two separate circuits to Alde and to Air8.


https://tab-rv.vanillacommunity.com/discussion/comment/182995/#Comment_182995
 

If you are talking about external panels, then I would definitely say a single 200w panel. No need to complicate things.