Battery %, Battery Usage, Charging

[MSL]

I picked up our 2019 22 Sport June 12th, brought it back to have leaks repaired June 15th, and now notice that when sitting in driveway battery goes from 100% to 75% - 80% in a day without any usage other than propane/smoke/etc. detectors and radio power. Is this nromal? (I know this has nothing to do with the leaks; just had to throw that in.) The unit has the 90 watt solar/AGM battery option. Is the SunExpolrer II % readout percent of available power, or percent of total power? If this is battery power usage in 12 hours without really using anything, I don't see how I could possibly dry camp for a day or two.

Also, had it unplugged from shore power yesterday during the day, and when I went to plug it in yesterday evening, there was no power thru the power cable. I reset the GFCI outlet I was using, then there was power. Never had this happen before. This morning I unplugged the power cable, and the charging status light on the SunExplorer II was red, although the battery level showed 100%.

Not sure what to make of this. Any help, advice, thoughts are welcome. Thanks in advance.

[AirMiles]

How many batteries does your Airstream have? If it has one AGM battery, it’s about 100 AmpHours of which 50% is usable giving you 50 Usable AmpHours. Two batteries will give you 100 Usable AmpHours.

Once you know your Usable AmpHours, you can start adding up how many AmpHours you project to use per day. Here is a list of Amp Draws for various items in my 2017 FC25FB Airstream. As you start adding up your potential usage, you will find that 50 AmpHours is very little and 100 is not that difficult to use per day.

Next you need an estimate of how many AmpHours your solar can restore each day. Typically, three times panel wattage can be produced on a sunny day without tree canopy. The formula is Watts x Voltage = Amps. Three times your 90 Watts of solar is 270 Watts. Divided by 13.5 volts equals 20 Amps. Twenty AmpHours is very little power that will be returned to your battery bank each day.

This is probably not the answer you were looking for, but your solar is about adequate to keep your battery charged while in storage. At most, it may be able to power your propane appliances, minimal lighting and water pump use while dry camping. You may want to consider getting a portable solar suitcase to supplement your factory solar. Adding a 100W suitcase may be enough to comfortably dry camp.

[uncle_bob]

Hi

Assuming you are running a stock trailer, the only thing that will give you a battery percentage are devices that are looking at the battery voltage. Depending on which one you are looking at, they can either be inaccurate or very inaccurate. Voltage drop in the wiring running to the device is one issue, there are others.

Solar wise, your location matters a lot. In the northeast you will (even in good conditions) do worse than in the southwest. Toss in shade and you have a lot of variables. A single panel should give you 5A in full sun. Five "equivalent peak" hours is not unusual in the northeast. That gets you to about 25AH a day.

Bob

[OTRA15]

Originally Posted by MSL

. . .
Any help, advice, thoughts are welcome. Thanks in advance.

Have you read your owner's manual thoroughly regarding battery etc. issues? It may not be perfectly organized, but it is a good start IMO.

Good luck,

Peter