[Dwight]

After four Optima batteries I gave up and bought a cheap lead battery that lasted five or six years.
I did recharge my buddy's Optima using a lead battery hooked parallel while charging. Tested bad at Auto Zone but after charged it lasted several years.

I copied this from Optima site



Do I need a special charger for my OPTIMA® battery?
Both the OPTIMA® Chargers Digital 400 & Digital 1200 12V Performance Battery Charger and Maintainer enhance the performance of OPTIMA and other AGM batteries, recover deeply discharged batteries and extend battery life. However, under normal vehicle starting applications, most regular automatic lead-acid battery chargers will properly charge an OPTIMA battery. However, since OPTIMA batteries are frequently used in high-performance applications or nonstandard vehicle starting applications, there are certain instances that must be given special considerations.

An OPTIMA battery is an AGM battery, not a gel battery or regular flooded battery. A deeply discharged OPTIMA battery (less than 10.5 volts) will not test or recharge properly if treated as a gel battery or regular flooded battery. A handheld electronic battery tester will most likely provide inaccurate test results.

An OPTIMA battery has the benefit of very low internal resistance, which allows high-amperage output as well as efficient charge acceptance. This benefit also allows an OPTIMA battery to run longer than its specified ratings and run to a lower voltage than typical flooded batteries. All of this can lead to confusion when it comes to recharging a deeply discharged OPTIMA. Most basic battery chargers have a built-in function to prevent charging a battery with less than 10.5 volts. If your OPTIMA battery is discharged below that, the battery charger may not start up.

Most high-quality, modern battery chargers now have built-in features to charge AGM batteries like OPTIMA batteries. Some have specific AGM settings which should be used to charge an OPTIMA battery. Do not use gel or gel/AGM settings, as they will not fully charge an OPTIMA battery and could damage it over time. However, even some AGM-compatible chargers will not recharge deeply-discharged (less than 10.5 volts) OPTIMA batteries. In those instances, it may be necessary to follow the parallel charging instructions described elsewhere in this FAQ.

For regular charging we recommend a maximum of 10-amps, 13.8-15.0 volts. For float charging, we recommend 1 amp maximum, 13.2-13.8 volts.

Under normal (engine-starting) conditions, an OPTIMA battery should never experience “at-rest” voltages below 10.5 volts. In these applications, most 12 volt chargers (old or new) or alternators will sufficiently recharge an OPTIMA battery with at least 10.5 volts. Typically, we only see issues with charging when it relates to stand-alone deep-cycling applications or severely discharged OPTIMA batteries.