Re: Charger Sizing... (too big?)
Just to expand a little... A charger can't be "too big" in electrical terms. But it can be "too big" in monetary terms.
That is, no point paying for a 100 amp charger if you're never going to use it to charge more than a single, group 31 battery. That would just be a silly waste of money. You wouldn't hurt the battery or the charger doing that, but you would beat the heck out of your wallet for no good reason!
Therefore, buy a charger that has the capacity for a battery bank somewhat larger than the biggest you ever expect it to have to charge. Don't go out and spend a boat-load of money, however, on the biggest charger you can find, just because "a charger can't be too big."