I need to install a security camera system on a United States 110v power circuit that is only on a night. The circuit is using an astronomical clock to turn on power and more accurately measure the amount of sunlight in a day before turning on the night power, compared to just having a timer on the circuit.
I need to install a PoE NVR with a 2 terabyte HDD, and two PoE cameras on this 110v circuit. The cameras will run during the day only, no night time operation. I want to charge the battery during the night while 110v power is on and have the cameras power off the battery during the day.
I have selected an AGM sealed 100ah 12v battery, a 12v 5amp battery charger (to ensure the battery gets fully charged during the night when there is power) and a 400w inverter. I do not need 400w at all, I only need roughly a 100w inverter but I do not believe a higher watt inverter consumes more power just because it is capable of a high watt output, it is just the devices plugged into the inverter that consume power, so the 400w inverter in fine and not very expensive. It has the battery connectors that I want is why I choose it.
An NVR with HDD can consume a range between 40watts and 200watts from what I have read online. Since I only have 2 cameras I believe I will be in the 40w to 60w range for my NVR. And remember, I will only be recording during the day, no nighttime recording, no night vision usage of the PoE cameras, the cameras will consume around 4w each.
So I am calculating a 70w consumption average of my PoE NVR and 2 PoE camera system.
By my calculations, a 12v 100ah battery will provide 1200 watt hours of power. To maintain good battery health of an AGM sealed deep cycle battery I want to keep the depth of discharge to 80%.
1200 watt hours * .8 = 960 watt hours.
If I am consuming 70w than that means I should get roughly 13 hours from the battery, 960/70 = 13.7 hours.
I am debating on whether I need a larger battery or not and also if my battery charger will be sufficient to recharge during the night, particularly in the peak of summer when you have the longest days and shortest nights.
For the battery size, I am concerned about the broad range between 40watts and 200watts NVR power consumption. With the battery charger I am concerned about the 80ah that will need charged back with a 5amp battery charger during the night. It will take 16 hours to recharge an 80% drained 12v 100ah battery with this 12v 5amp battery charger.
Any insight into where my calculations might be wrong would be greatly appreciated.