Renogy 200 ah AGM

Anybody have experience with this Renogy 200 Ah AGM?
Curiously they rate it at 200 ah at a 10 hour discharge rate instead the typical 20 hour. They say it's 'specifically designed for solar energy storage applications', but they don't go into details so I'll just take that as marketing BS. Similar, but not exact stats as the UPG battery in the other thread, a little heavier.
Comments
More or less, Lead acid batteries are (to a first degree) Amp*Hours in = Amp*Hours out (they are charge flow efficient). Only when you charge > gassing voltage, then do the Lead Acid Batteries become less efficient (i.e., charging current in releases Hydrogen and Oxygen gases, that you never can "recover" and current flow).
Now, when you look at energy---Power (Watts) = Voltage * Current and Energy = Voltage * Current * Time (typically, for our needs; Volts, Amps, and Hours).
So when a battery starts at 100% SoC and Vbatt-full=~12.8 volts (lead acid 12 volt battery), and discharges to Vbatt-empty=~10.5 volts, the total energy (Watt*Hours) is dependent on battery voltage, current draw, internal resistance, chemistry activity, etc...
For "the old fashion" usage of batteries--Filament lamps, electric motors, tube radios, etc... The Amp draw from the DC loads are (sort) fairly consistent. At 12.8volts, you get 10 amp draw, and at 10.5 volts, you get a 10 amp draw--The the "description of battery performance" in Amp*Hours is good enough for those loads.
Today, we have a lot of constant power loads... LEDs, Computer, and the general catch all of AC Inverters.... For example, you want to run a 10 amp load at 120 VAC... That is 120 Watts. The inverter DC input current requirements are "variable". Ignoring efficiency and stuff for the moment:
- Power = Volts * Current
- Current = Volts / Current
- 120 Watts / 12.8 volts = 9.375 Amps
- 120 Watts / 10.5 volts = 11.43 Amps
So, something that I have noticed over the years (may have been many decades ago--And I just did not pay attention), now battery systems that are for UPS systems (basically AC Charger->Battery bank->AC Inverter), where the AC inverter is modeled as a constant power source, I am seeing batteries defined in Watt*Hours per cell (or per battery)...A more "accurate" number for our "modern AC constant power loads".
Since we are generally working with rules of thumbs here... Call a 12 volt battery "12.0 volts nominal" discharging and "14.5 volts charging" (for flooded cell)--Sort of gives us a "good enough" estimate of battery performance when doing the "solar math" without too many confusing (and over conservative) fudge factors thrown in.
-Bill