Hoe to schedule batteries to not discharge

[BaggiesMatt]

I seem to have lost some battery settings.

I used to have enable force charge, and enable charge from the grid and using them in different combinations I was able to achieve a scenario where the batteries didnt charge, or discharge.

I want to set up that between 2am and 5am I don't want the batteries to charge from the grid, or discharge to run the house. I want the house to run on the grid, and not charge the batteries at all.

How do I do this now?

[Dave Foster]

Which version of the app are you using ?

The charge times are still there but there is only one switch now (enable grid charge).

If you want to stop discharge you set a time period and leave the charge from grid switch disabled.

If you want to charge the batteries you set a time period and set the charge from grid switch to enabled.

[BaggiesMatt]

Hi Dave,

I have 2 apps, Foxcloud - V1.50.23 & FoxCloud2.0 v2.1.32

I also have access to my set up via the web browser.

Thanks for your reply. I have tried to set a time period and leave the charge from grid switch disabled, and this seemed to work but there was still a slight discharge - it was not a complete battery backout that I was hoping for.

I am attaching a screen shot, in which I use both the time periods. do you think that my settings should between

00:30 and 05:30 allow the battery to charge from grid, and then between 05:30 and 07:00 run 100% of my house load from the grid.

[Dave Foster]

Yes even when the battery isn’t being used to power the load, a small amount of power will be used to keep the inverter from going into standby (it doesn’t take this from grid) - usually between 30 and 70 watts but a fairly low drain.

I’m assuming you are on an eco tariff from 00:30 to 07:00? - if you want to charge your batteries to 100% and not use them to power the house, the best option is to set a single charge period to cover that entire period with charge from grid enabled.

When the battery hits 100% it will stop charging, but it also won’t discharge either and your house load will be powered from grid - leaving you at 7am with a full battery.

[BaggiesMatt]

thanks again, great info.

I am just trying to learn how to set the battery so they don't discharge. I have an electric vehicle, that I want to charge on my cheap tariff, but I want it to be from the grid, and not the battery. I am thinking about not charging the batteries from the grid, I have heard this might prolong their life a little. so if I set a time period and leave the charge from grid switch disabled, and car charge time the same, the car should use the grid?

[Dave Foster]

Yes that’s it, just set a time period that covers the time your EV will charge with charge from grid disabled and the batteries will not be used to charge the car (or power your house), they are effectively in standby.

[BaggiesMatt]

thanks again Dave, that makes sense and my testing last night showed this is working. while I am talking to someone helpful, can you help me understand what battery reserve capacity and system min SOC are about?

thanks

[Dave Foster]

no problem,

‘System Min SoC’ (where SoC= state of charge) is the absolute minimum the batteries are allowed to go to and is normally set to 10% (it can’t be any lower than this as the batteries have a maximum 90% depth of discharge).

The Battery Reserve Capacity is for those people that have the inverter wired with an EPS (emergency power supply), so if you set this to 25% then whilst on grid it won’t go any lower than 25%, but should the grid fail and it switches over to EPS it will use the ‘reserve’ power until it hits the system min soc (a bit like a reserve fuel tank).

For the majority of people these 2 values are set the same and usually at 10%.

In winter, where the batteries are exposed some people set the System Min SoC higher to 15% or 20% so if the batteries get extremely cold and won’t take a charge with their internal self discharge they won’t go below 10% which can damage them.

[Badfly]

Hi, I had an install recently and foresaw the issue you have about the EV battery charging only from the grid. I told my installer to add an additional Henley block so that the system is wired that the EV battery is connected to the grid before the battery connection and load monitoring CT for the Solar battery. By doing this the battery system never sees the EV battery as a load and will not discharge into the car. It’s an easy and permanent fix if you get an electrician in to sort it. I am on Octopus Intelligent Go and my car can charge at anytime of the day without impacting on the Solar battery system. EV connected to grid and household load connected to Solar battery system.

[Dave Foster]

Hi, I had an install recently and foresaw the issue you have about the EV battery charging only from the grid. I told my installer to add an additional Henley block so that the system is wired that the EV battery is connected to the grid before the battery connection and load monitoring CT for the Solar battery. By doing this the battery system never sees the EV battery as a load and will not discharge into the car. It’s an easy and permanent fix if you get an electrician in to sort it. I am on Octopus Intelligent Go and my car can charge at anytime of the day without impacting on the Solar battery system. EV connected to grid and household load connected to Solar battery system.

This is always the best way to deal with it, removes so much stress - particularly with the intelligent anytime charging tariffs

[DoingMyBit]

With this Henley block solution, does it mean that solar can never charge the car?

I'm thinking of a scenario where there is a multi-day grid failure and you want the car to get some charge....?

Is there a way instead to use Home Assistant to get the Octopus Intelligent Go charging times once the car is plugged in and charge the battery instead?

[Dave Foster]

Yes there is a home assistant solution where it can detect the EV charger and protect the battery discharge so they don’t discharge (this is what I use) - there is always a very small risk that your home assistant for whatever reason doesn’t work and that will flatten the battery.

With the Henley block solution the EV charger will never discharge the battery as the inverter cannot see the load it creates - however, the EV charger would still be able to see excess solar and use that to balance its charging.

[DoingMyBit]

Thanks Dave! Would you be so kind as to point me to the HA solution you use?

[Dave Foster]

If you have a read of this thread - it's a bit old now so home assistant may have changed a few things viewtopic.php?p=1994

but the easiest solution you will find on this post, it quite simply sets a charge period when it sees the zappi charging and clears it when it's not. viewtopic.php?p=1994#p1994

Note as this uses a charge period (charge period 2) this won't work if you have schedules set - instead you will have to set the maximum battery discharge current to zero and reset it to 35A when finished.