You might just have bad luck with both batteries. I've bought two Excite batteries, first to my Chevy Van. That lasted one camshaft break-in and driving from garage to street to reverse vehicle inside garage and two years standing - listening music and recharging regularly.
Second is, again, Excite for RX400h, that lasted about half year and stopped charging to full. It was diagnosed to have one collapsed cell and replaced by warranty.
I'm guessing Van's Excite suffered even more massive collapsing. RX battery is running strong now over half years so all is good eventually.
These were normal batteries, not AGM. Next batteries will be AGM or Li-Ion.
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