Can anyone recomend a widget?

This graph shows my night rate slot (green), grid import (blue) and costs (orange).
I have noticed that if my battery reaches the set SoC before the charging time slot finishes, there is quite a lot of "hunting" (red box). Not sure what this would be but it is using power!

Ignore the spike towards the end of red box - that's me making my coffee!
I would like an Automation or Plugin or whatever that will allow me to:

1. Dial-in the required SoC
2. Dial-in the required end time
3. Compute/guesstimate when the battery should start charging to meet points 1. & 2.
   Is this possible?

Regards, M.

mprowe there are several ways to accomplish automatically charging the battery to certain levels. Search the forum, but PALM, wonderwatt, octopus r&d and home assistant with either your own automation or something like predbat are all viable solutions.

Depends how sophisticated you want to get.

geoffreycoan
Oh.... Sorry! I forgot to mention that I was hoping for a Home Automation solution.

Regards, M.

I won't go into the details of why, but to stop the oscillations all you need to do is set the charge power to 0W. So you just need to make a helper in HA that
1: fires a command setting power to 0 when SOC >(your chosen SOC)
2: fires a command setting power to max when SOC =<(your chosen SOC)

You equally can set discharge to 0W and it stops the oscillations but then your battery is stuck idle, so charge power works better.

hoggy
My apologies, I don't think I'm explaining myself very well? Maybe this is a better phrase:
"How do I charge to 100%, so that it finishes at 07:00". Considering that the start SoC is differs day-to-day.

mprowe I don't use home assistant, but I use a simple python script for something similar. Rather than adjusting the start time, it adjusts the charging power, aiming to take the full cheap period to reach target SoC. Should be easy enough to modify to do what you need.

DD
Thank you. that sounds like I could manage that!
It seems that I only have to place a python script in:
<config>/python_scripts/ folder
Are you willing to share?
Regards, M.

mprowe If I got it right, you should find it in https://github.com/divenal/givenergy-scripts
I had meant to tidy it up a bit before uploading, but since I didn't get a chance, may as well upload it as-is.

Note that if the battery is already close to the target charge, it just charges at a fixed rate. So that won't work in your situation.

Not sure it makes sense to stop using the grid during the cheap period. If you use the battery instead then you are using the cheap units put into it with round trip loses in and out instead of just using them straight from the grid without any loses.

After much thought I have decided it is best to simply charge our battery to 100% / run the house for the full flux cheap period regardless of the amount of sun predicted, etc. If it is sunny it just starts exporting sooner for longer at nearly the same unit price as the cheap charge and is more likely to export more at the peak rate and less like to take from the grid then.

On a very dull day with no solar it will have more left when it comes back to charging from grid again. So if we end the cheap charge period with less than 100% by finishing early we start with less the next day and put more in then.

When I was on flux last summer I came to a different conclusion that by the time you include inverter and conversion losses, it generally wasn’t worth charging the battery overnight to hasten the start of export the next day.
As you say the overnight import and daytime export rates are very similar.

Its pence difference whichever strategy you follow though

It’s a good point about pre-charging the battery means more likely to be exporting in the peak period. In my case in summer the batteries would get full by lunchtime anyway so it wasn’t a consideration for me, but if your solar panel to battery ratio is different the tipping point will change

Not sure it makes sense to stop using the grid during the cheap period. If you use the battery instead then you are using the cheap units put into it with round trip loses in and out instead of just using them straight from the grid without any loses.

Agreed. Having pondered further, one option might be to use the timed-pause feature from the web portal, if your inverter supports it. You could set the battery to pause-discharge for the entire cheap period. I assume that any timed charge will still operate. This way, even if you delay the start of the charge until later in the cheap period, it will run the house from the grid rather than the battery.
I'm not sure if pausing the discharge would prevent the hunting happening at the end of the charge period. If the problem is that the firmware is trying to dissipate some power because it has over-charged slightly, then pausing discharge might not address that.