This may help..
Charging Information For Lead Acid Batteries â€“ Battery University
You are likely not getting a full charge on the battery as its not being charged long enough.
Also...cold temps .... below 70ish ... sucks the charge out of batteries. So if you are 50% charged...when the temp drops and cold soaks the battery you may only have 25%....
???... Do you have a SoC indicator that shows battery voltages in the coach? Even indicator LEDs will help. First thing...flip on the coach master everthing else off... Check the SoC!
Post a chart like this for reference next to your SoC meter.
Last...dig into that bag of flyers & manuals that came with the RV. Find the manual for your charger. Read ... and understand how it works when charging....every manufacturer is different & your charging scheme may vary.
NOTE: You can't check SoC while charging....that will tell you the voltage that is being applied to the battery!!! **** Not the SoC. Battery should be rested for a short time after charging for a better reading.
**** That is also a good thing.. A reading of something like 13+ to 14+V when charging tells you that the battery is being charged but is not the battery's SoC.
I hope this helps...