Good batteries if treated right. They don't like slow charging, it causes slow loss of capacity. I recommend a 10 amp charging rate or better for the bulk charge. I recommend using individual battery regulators, like Rudman regs. They need a little nudging to stay balanced and can be damaged from excess overcharging (and like any lead acid battery, damaged from regular undercharging.)
Another option is the zener reg. This is a pair of 5 watt zeners mounted in ring terminals as heat sinks with a small bulb (like a PR2 flashlight bulb) between them. Lee Hart generally recommends using a 6.2 and 6.8 volt zener per battery so they turn on starting at 13 volts but with Optimas having a resting voltage of 13.1 I would recommend using 6.8 volt zeners at both terminals.
This isn't a very power reg, it can only gently nudge them toward balance. It is cheap, consisting of just a couple dollars in parts per battery. You can use Optimas without regs but you get to do some babysitting every so often to keep things in line.
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