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.
Having used LA batteries for years on watering and fencing, the day I discovered LFP batteries was a glorious day.
They last forever, they discharge down to nothing with no damage, you don’t get corrosion on the terminals. You can’t boil them, you don’t need to check water level, they weigh half as much for the capacity.
Even though initially expensive, I calculated they’re about a quarter of the cost over the long term than LA because of the cycle count and amount I need for the extended capacity. I get about 30-40% of a LA battery’s capacity without doing lasting harm to it, with LFP I can abuse that thing all the way down until it’s completely exhausted and it charges right back up again.
Only thing I have to watch is charging them below freezing, so I have to run them in an insulated and heated box in the winter.
It gets very cold where I live. I should look into an auto shut off of the battery charger if it dips too cold in my basement. Unlikely to go below 32F but you never know. The BMS will do it itself, but I’d rather not rely on it.
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).