Woot has the APC SMC1500-2UC in new/open box condition, for a limited time (as their deals often are), for $327.59. Free shipping if you’re an Amazon Prime member:
Note that this model doesn’t have a slot for a network interface. It has its own onboard, but it appears that it’s intended for cloud-based monitoring; no idea whether or to what extent it does or can be made to work for local network monitoring.
LFP batteries are relatively standard for house batteries now, as part of a solar PV system either with a hybrid inverter or AC coupled.
For example, Pylontech US5000C batteries are certified UL9540A which is the test for thermal runaway.
I’d trust LFPmore than I’d trust a lead acid battery as part of a UPS.
I think I’d agree with this if, and only if, the UPS had been designed for LFP. Unfortunately, the only such models currently are ridiculously expensive.
If by UPS you specifically mean the battery management system, then yes, it’s a somewhat obvious point given that the charging and discharging is based around the chemistry, which is no different than lead acid cells (edit: ie the battery management system must always be related to the needs of the chemistry, a lead acid BMS needs a lead acid setting, and LFP BMS needs an LFP setting. The standalone BMS available now usually have both settings from what I can tell).
Removing the lead acid cells from an old UPS and adding LFP cells is dangerous because the BMS does not know what it’s charging, but there are standalone BMS designed for LFP. You could self build an LFP UPS now, just as you could self build a lead acid UPS. It’s really a matter of how much you want to invest, you could spend £20,000 building an islanded system that will run off grid with DC coupled solar PV and a self built 80kWh LFP battery system for the entire house. Can’t have a power cut in that scenario short of a catastrophic malfunction ie house fire from another source.
One of the beautiful things related to the MikroTik line of switches, routers, etc is a validated, very wide input voltage range for DC. That makes them pretty much perfect for simple DIY charging / UPS systems that eschew the AC middleman step up/step down loss associated with traditional UPS’.
I don’t expect to have time to work on this until later this winter but I plan to convert my network rigs to run on DIY LFP + picobox UPS solutions.
Constantin, will this DIY solution be charged from AC, or some other source ie solar PV? I’m interested in seeing how you do it either way.
I have an extant DIY UPS I built here many moons ago to charge via USB and the landline phone base.
AC PSU to charge batteries and a built in
switchover to the Lead Acid battery if power fails. IIRC, the Picobox solution uses MOSFETs or something similar as a failover switch, so the changeover is almost instantaneous and even less lossy than Schottky diodes.
For my network gear, I’d build something similar, the power draw is not that different. The big delta would be the battery technology (LiFePO not Pb) and a bigger reserve. I may even abandon the old unit and repurpose the board since we have a lot more power banks here to charge phones with and the landline is becoming increasingly irrelevant.
Shouldn’t he have used eg?
eg gives one example of many (waterwheel, an exercise bike powered by hyperactive toddlers, a personal minature fusion reactor etc), but I’m not aware of any other effective choices that solar PV, therefore ie would be correct IMO.
FWIW it is technically trivial to build a small dc-dc coupled solar array to charge an LFP battery bank and then use that to power small electric equipment eg a router, on a permenant basis (say, 50W/h) could probably be powered by a 4 panel, 400W/panel array 24/7, 365 days a year any where between Manchester and the equator.
