I've used various chargers and trickle chargers over the years. The one that was on it when it failed was this one:

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I had it set to AGM mode and it showed fully charged....but it wouldn't start the car. My battery tester showed voltage was good but as soon as I hit the LOAD button it dropped to the "Weak" zone.
So...it's gone and I'm done with Optima. So nice to be driving my mustang today not worrying if it will start without a jump! And I saved $50 vs the cost of a new Optima.
The thing that I think is the worst is they've obviously reengineered the battery to just clear the 3 year full replacement period so they can maximize income and all they've really managed to do is drive off what used to be a loyal customer base. In the mean time, in an age when we are trying to be a bit greener...they have created a need to produce more product than necessary by redesigning a good product to make it less than mediocre.
Rant off.