Sump pumps are one of the most boring parts of home ownership. Until that one storm comes and suddenly they’re interesting.
After losing power one time this summer, I got paranoid and decided to build a battery backup. Home Depot had the basement watchdog systems, but they seemed high maintenance and I wanted something that would let me be lazier. I went with a LifePo4 battery system, that will (hopefully) get me 10 to 15 years. The battery charger has a float/storage mode so it can stay on 24/7. Doing some test runs, I think I can get about 400 cycles out of the battery before it hits 0%. I added some additional safety features (DC circuit breaker, GFCI with auto-on, Lithium fire extinguiser, etc), and added some battery powered lights and a basket of hand tools, so in the event the power goes out in the dead of night, something goes wrong, and I have to get my feet wet, everything is there ready to go.
If your basement goes below freezing, you have a lot bigger problems than if that battery gets borked because it was trickle charging. You’re probably right to not trust the BMS though, unless you can get into it and confirm the cutoff temperature. I think the JKBMS comes from the factory set to -6C which is bullshit.
That’s a good point…I have a new furnace, and I’ve been here several years without pipes freezing (knock on wood).