I have a Bosch L5077 180 Ah, 12 V deep-cycle sealed Pb battery for my solar setup. I bought it recently (two weeks ago) but since the weather was rainy the last two weeks, and the solar panels didn't produce any significant power, I keep charging it on-grid with a 10 A, 3-stage smart charger.
Assuming that this battery has a capacity of 180 Ah which is around 2 kWh of energy, the battery is almost fully drained (11.3 V) before even consuming 1 kWh or so.
So, in six hours of usage which usually reaches the threshold in which the inverter shuts down, I'm using a 43", 50 W LED TV, one 32" 35 W LED TV, a laptop charging (60 W/hour) and a few home LED lights now and then.
With a quick calculation we have:
- 43" LED TV 50 W x 6 hours = 300 W
- 32" LED TV 35 W x 6 hours = 210 W
- Laptop charger 60 W x 6 hours = 360 W
- Inverter 1500 W consumption, let's say 30 W x 6 hours = 180 W.
- Lights, which shouldn't be more than 100 W total in those 6 hours, as I don't use the lights much.
The result is 1050 W of energy consumed and the battery is fully drained.
Where did the rest of the 85 Ah go?
The charger is always charging the battery fully; when the battery is freshly charged it will show a value of 13.6 V on the PWM charger; 2 hours later it shows between 13.4-13.5 V so I guess the battery can't be damaged so soon.