Here is my EarthX eXperience:
I bought my first one from our local Explorer post, Youth Exploring Aviation. My younger son Matthew and I were involved for a year. We restored a 1946 Aeronca Chief. It had no electrical system but the rebuilt engine that went into it had a starter pad, so they added a starter and and EarthX battery so they didn't have to hand prop it. Later the IAs were not happy with the paper trail and they removed the EarthX, and it was offered to me at half price. I bought it, it sat around for a long time, and when I went to use it - kaput. I borrowed the right Optimate charger from a neighbor but it did not come back. I think between the poor usage, i.e. use it until it needed to be charged, then sitting must have killed it. So I dried my tears, bought a new battery and my own Optimate. Life was good.
We started having occasional battery warning indications - the little LED would flash. I have a remote LED in the cockpit next to the MFD. It always worked, and the warnings would go away after a while, but I didn't like it. From the manual it may have had a weak cell. So I bought #3 - and still had some flashing LED issues. Great. This led me down the rabbit hole of VRs. Relevant thread linked below, and the last post (currently) of that thread links another good VR thread.
viewtopic.php?f=6&t=7412That story had a happy ending with my new John Deere VR. The battery warning indications went away. Battery #2 may be fine - still charges and I used it to run my CPAP machine during a winter camping trip last month.
Despite all this, hard to beat the EarthX in terms of performance and weight. I can't afford a lead acid battery.
If I was in your situation, I'd do the following:
1) Buy an optimate charger and see if you can save it.
2) If not, buy a new battery.
3) Charge the battery regularly. We put ours on charge after every flight, except when going XC.
4) Consider the John Deere VR. It charges at 14.6-14.7 and the EarthX is happy there.