We keep our batteries under continuous charge when we are away and have had extraordinary battery
Our motorhome batteries, Trojan 105s have lasted for 14 years. We kept them charged with a Progresive Converter with Smart charger. Our traditional Ford Truck battery
was replaced after 9 years.
We're usually gone about 7 months and the water level is usually down a little but the plates were never above the water/acid level. We simply add a little distilled water and everything's normal.
With the Scamp
the batteries are never off the charger, either from the Converter, Solar
panels or the tow vehicle except at night when boondocking