Most miners are NOT rated for operation on the "nominal" 13.8 volts common Lead-Acid batteries provide - much less the 14-15 volts that is common when the battery is CHARGING.
That's why I worded it the way I did. I said to switch the battery to supply the miners when utility power is disconnected. Therefore the 13.8V charger will never be connected to the miner while it is powered. The battery would be on discharge which would be within specs.
13.8V is the correct charging voltage for lead-acid batteries, which are the best bang for the buck choice. There are many other batteries but they'll cost you more. Buying anything for mining that exceed 3 year lifespan is probably not the best idea as everything could be obsolete by then.
I didn't submit a comprehensive design with bill of materials and cost justification model because nobody gave me a PO to engineer this project.
I also didn't see an engineering design for the grossly impracticable water storage or cost justification PV model ideas. I'd love to see them because the ideas only gave me a mild chuckle. A submitted design would be worth sharing for us all to LOL.
Thing is, miners run on 12VDC. A UPS for miners is really simple as it is only a charger, battery and a relay. Crazy cheap, demonstrated millions of times as effective, easy to design with 100% certainty of performance effectiveness. My suggestion to the OP would actually work, and be cheaper than any other option that is within his original ask.
