I've been seeing a local reseller on and off the last couple of years on OLX, I finally messaged him and asked about what they had.
did you test if they really had 85% capacity and not lower?
So this question has a multifaceted answer. Amaron publishes datasheets for their Quanta batteries, the datasheet for this battery shows a State of Charge chart based on voltage at the terminals with nothing connected to it. I charged the battery at 13.8V for 24 hours, let it rest for an hour and then measured the voltage and cross referenced the chart:
I measured 13V, so that's right around 85%. However I could be reading this chart completely wrong (or what it's for) so I'm going to do an actual capacity by connecting a few headlight bulbs and see how long it takes to reach the safe cut off voltage that's in another table on the datasheet:
I'm thinking a 18A load (4x 55w bulbs) until the voltage drops to 10.2 should return a value that's close to 72AH (85% of 85AH). The maths get a bit mathematical at this point and I might need to consult with someone more intelligent than me to figure this out. But that'll be sometime next week.
The multifaceted part of the question is what exactly is the capacity of a lead acid battery? Again, from the datasheet, this depends how much load you're putting on the battery and how long you want to use it:
If we want to use the full capacity of the battery (discharging until 10.5V in 5 hours, for example, from the table above) then we'll get only a little over 200 cycles from the battery. Which is about 7 months of life if you have daily power cuts lasting 5 hours each. Maybe less, depending on what the ambient temperature is in your area.
But if you oversize your batteries and discharge only to about 12.5V or 50%, then you'll get almost 2x to 3x battery life.
I have a 150AH battery connected to the wifi router (way over sized) but it's six years old at this point and I did a capacity test last year and I got like 42 hours of back up time:
Are all UPS brands taking this much power and doing nothing? They're NOT doing nothing. A UPS has circuitry that, at minimum: keeps the battery fully charged to be able to provide max backup time monitors AC mains for voltage fluctuation to disconnect it from PC and power it via...
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