Battery draining overnight

[Fox1438]

I've recently had a system installed and find that the battery discharges slowly overnight until it reaches a couple of % below the minimum charge (set at 20%), even though there is only very minimal use of electricity. Is that to be expected or is it something to worry about?

[Dave Foster]

It's perfectly normal to do that, the inverter and batteries takes some power to stay operational and ready. This is taken from the DC side rather than use the grid (DC = batteries or solar during the day). The amount of power it uses depends on the inverter and the number of batteries you have but typically in the range 30 to 100Wh.

[Dad]

What battery capacity do you have? What percentage of charge is in the battery when you go to bed?

Trying to understand if you are losing a lot of charge overnight or some charge (which as Dave points out is normal).

[Fox1438]

Thank you for getting back to me so quickly. We have 2 x 2.38 kwH batteries, and they are often charged at 40-50% by about midnight and then drain down to just under 20% by about 5:00 or 6:00, not sure if that is normal? Thanks!

[Dave Foster]

That sounds about right,

To do some quick maths if you assume 45% at midnight and 20% at 6am, then 25% of (2*2.38) = 1.19kWh for 6 hours or 198 watts per hour so you obviously have quite a low house base load (fridges, clocks, chargers etc..)

[Fox1438]

Thank you very much, Dave, that's reassuring