Charging slots not the cheapest

[CTSchorsch]

Hi,

why is predbat using this slots for charging the battery ? And not the earlier ones with cheaper rates ? Is this because a wrong configuration or a normal behavior ?

thanks
Georg

[gcoan]

specifically which slots do you think predbat is charging the battery in?

you've clipped the top off the plan so I can't see the column labels and haven't supplied a logfile or details of your configuration, but I can guess at the column labels and what I see is:

22:45 to 02:15 import rates are 31-32ct, your battery SoC is at 10%, presumably your minimum level, you have a small bit of house load and this is being met from grid import so you get a small bit of costs in the next to last column. Predbat status is shown as arrow to the right meaning Demand mode
02:30 to 04:30 rates drop to 29ct, predbat charges your battery
04:45 to 06:30 rates similar, increasingly slightly, predbat holds your battery at full, preserving the battery for later more expensive periods
06:45 to 07:45 rates increase to 32,33ct, Predbat releases your battery to meet house load

looks OK to me

if you think there is a bug you need to provide much more information than just a partial screenshot of the plan

[CTSchorsch]

No, I don't think it's a bug. Please don't get me wrong.
I'm still learning how everything works, and I've noticed that the slots at 2:00 and 2:15 are cheaper than those at 6:15 and 6:30. I had expected the loading window to start a little earlier.

[gcoan]

In general I'd say to trust what predbat is doing, believe me, you can go mad by trying to analyse and double check the plan

But answering your question, whilst 2:00 and 2;15 are cheaper than 6:15 and 6:30, the following slots are cheaper still. Predbat is filling your battery in the 29.xx slots from 2:30 which is the cheapest time to fill it and has the battery full by 04:15. If it started charging at 2:00 then your first two battery charges would have been at 30.11 and 30.02 which is more expensive than when Predbat planned the charging.

There are overhead and conversion losses when charging and discharging your battery, you can see these if you turn plan debug mode on. With these losses it is sometimes not worth discharging the battery because the effective rate is more expensive than to directly grid charge. That's why Predbat doesn't start discharging the battery at 6:15.

[CTSchorsch]

Should I just trust foreign software? :)
But you're right, of course. That looks very correct.
Thanks for your work, and your really fast response here

[CTSchorsch]

I still don't really understand it. I played around a bit with the “Debug enable” and “Car charging hold” switches. The plan then says that charging should only take place tomorrow.
Here is a picture of my electricity price. The bar for tomorrow is the predbat slot where charging should take place.

I actually expect to load tonight.

I'm probably too impatient.