Originally Posted by alan H
also the converter at this point does not work for charging when plugged into shore power
While you are at Walmart, pondering batteries, look at the cheap, smart chargers.
You might do well to buy a small battery charger and not worry about the converter for now. Something in the 4-6 amp size should do the trick. Larger will be more expensive, but won't hurt.
You'll know it's a smart charger if it's light weight
and says "multi-stage", or something to that affect. Pretty much the smallest one will handle your described needs. "Smart", and "Multi-Stage" indicate you can leave it connected without hurting the battery.
If you plan to add more loads, you could splurge and get a Group 27 battery and a slightly larger charger.
Be aware that if you let your battery get below about 10.5 volts, a "smart" charger will not charge it back up. This is not a malfunction. Smart chargers use battery voltage to turn them on, and if the bat is dead, they won't turn on. The fix is to jump them with jumper cables, or use an old-fashioned ferro-resonant charger from yesteryear (heavy with a large transformer inside). The old chargers put out power regardless of the state of charge of the battery. Once the 10.5 threshold is reached, the smart charger will take over. I keep both types available in the garage. But do not leave the older style connected indefinitely, or the battery will run dry and be ruined.