# Solar battery draining too fast

So I have a Bosch L5077 180A 12v deep cycle sealed Pb battery for my solar setup. I bought it recently (2 weeks ago) but since the weather was rainy the last 2 weeks and the solar panels didn't produce any significant power, I keep charging it on-grid with a 10A 3-stage smart charger.

Assuming that this battery can hold a capacity of 180AH which is around 2kWh of energy, the battery is almost fully drained (11.3v) before even consuming 1kWh or so.

So, in 6 hours of usage which usually reaches the threshold in which the inverter shuts down, I'm using a 43'' 50w LEDTV, one 32'' 35w LEDTV, a laptop charging (60w/hour) and few home led lights opening now and then.

With a quick calculation we have :

43'' LEDTV 50w x 6 hours = 300W

32'' LEDTV 35w x 6 hours = 210W

Laptop charger 60w x 6 hours = 360W

Inverter 1500W consumption, let's say 30w x 6 hours = 180W

And the lights which shouldn't be more than 100watts total in those 6 hours as I don't use much the lights.

The result is 1050w of energy consumed and the battery is fully drained.

Where did the rest of 85 amps went to ? The charger is always charging fully the battery, when the battery is fresh charged it will show a value of 13.6V in PWM charger, while 2 hours later it will show between 13.4-13.5V so I guess the battery can't be damaged so soon.

Any ideas ?

• Have you accounted for DC/AC conversion efficiency of the inverter under the load of your use case? Nov 21, 2019 at 23:23
• How to do that ? I have no idea how much the inverter draws in standby or under load. It mentions nothing also in its manual. Nov 21, 2019 at 23:37
• the battery is probably rated at 9 A over a 20 hour discharge interval ... for example, if you draw 45 A, then the battery will last less than 4 hours ... refer to the datasheet, if you can find one (i could not find it) Nov 22, 2019 at 1:08
• How do you know the various loads? Especially the power for TVs will vary considerably depending upon usage - in particular the backlight intensity setting. I don't think you can conclude much unless you actually measure the current being taken from the battery. Nov 22, 2019 at 1:41
• take a gander at this e-education.psu.edu/eme812/node/738 Nov 22, 2019 at 1:43