[Chuck v]

Lead acid (flooded cell) storage batteries of the type used in most RVs will 'self-discharge' over time, and you need to top off the charge when the rig is not in use.

Also, this type of battery can be permanently damaged if its charge is let to go completely flat at any point. The battery that was new in 2021 may no longer be of service...depending on how deeply it was discharged.


Look on your existing battery -- it should have a group number and a service rating. Batteries generally fall into "starting" for cranking an engine, "deep cycle" for long, slow discharge as in RV house batteries, and 'marine" which is a hybrid of the first two use classes.


Starting batteries are rated in terms of CCA (cold cranking amps) which is a measure of the high discharge rate an engine starting service places on such a battery.


Deep cycle batteries are often rated in AH (ampere-hours) which states how long a constant load can be supplied. There are 5 hour and 20 hour ratings and perhaps a few more, but suffice it to say the slower you take out the energy the more total energy you will get. Batteries are chemical storage systems, and the discharge at higher rates will limit the total yield. The AH rating will also determine the optimum recharge rate -- most batteries suggest a C/5 or C/10 rate, meaning that the charging is done at a rate of the capacity divided by 5 or 10. Recharging a battery takes more energy than was drained (the cycle is not nearly 100% efficient...) so it takes longer to recharge than to discharge at the same current flow.


Since you are talking about a single battery, you may have a small tow-able rig. Some larger RVs have banks of multiple batteries, and those with engines and generators may have multiple banks. My own diesel pusher coach had a two battery bank for engine starting, another two battery bank for 'house' use (lights, fans...) and a third 4 battery bank for the inverter and to start the generator.


You can get more specific answers to your questions on this forum if you state the model and year of your RV -- most of us include such information in our signature blocks.


Chuck