Block Battery Discharge

Hello!

I had a PV, inverter and 9.5 battery system installed at the end of last week and the commissioning finished over the weekend, so now I'm into configuring stuff! For context:

I do NOT have a smart/economy 7 type tariff yet. Everything pulled from the grid costs the same.
I have an Outlander PHEV. Being a PHEV the battery's small so I've not bothered getting a proper car charger yet - I just use the 3-pin plug. This means that there's no smartness - the inverter can't tell the difference between normal home load & when the car's charging, so will empty the battery in order to fill up the car.

I'd like to avoid that from happening. Both in the short term to avoid the waste of going from battery to battery, in the medium term to fill up both car & battery with cheaper night time electricity & making sure I'll be battery only during 4-7pm when that National Grid peak time demand switching thing happens. In the longer term I'll be getting a smart charger anyway.

The car can be filled up two ways - there's a timer function & an 'charge now' override. Doing the latter is, I think, simple - there's a 'pause' setting on the app and I just use that, all power will come from PV/the grid & the car charges normally. When it's full I turn the battery back on & it charges from excess PV like normal. Using the timer is harder - last night I had a 2/3rds full battery, set the 'Timed Discharge' to be from 06:00 - 23:59... and I woke up to an empty battery and a full car.

So my main question - what went wrong? I expected Timed Discharge to only allow discharging to the home between the hours set - it's certainly what the wording on the app implies. Should I be doing it another way? Because I'm still on a flat tariff I have no desire right now to charge the battery from the grid, but I'm wondering if charge & discharge both have to be set to get them working?

Timed discharge is in fact a forced discharge period at full power (3kw in my case). This will also discharge to the grid if houshold load is under inverter output. Generally, people only use this mode to define an export period to get the best export rates. This is why your battery was empty. I never use it.

If you want a period where the battery keeps schtum what ever demand there is then set the batttery discharge rate to 0w through the portal (My Inverter | Settings | Battery Options. You can do it through the app too but experience suggest it's not as reliable as through the portal.

You will need to set it back again when you have finished.

Clearly, the best way to achieve this is to automate it (I use Home Assistant and GivTCP) but there are other ways that I'm sure others will advise.

That can't be right. There's two settings:

Timed Discharge: This mode will discharge your batteries to your home during a period you define
Timed Export: This mode will hold your battery power and discharge it at full power during a period you define

The app seems to mirror this by having a 'Scheduled' discharge mode and then an option for Consumption Type: 'Home Demand' and 'Full Export'. I set the Home Demand option in the app, and I checked the portal in the morning and it had the Timed Discharge setting enabled. Regardless of the options - I set a time period of 06:00 to 23:59, and the battery was drained from 00:30 (when the timed charging in the car starts).

These are the options I can think of:

Timed Discharge does not do what it says it does, or I've severely misunderstood something
The start/end time of Timed Discharge is backwards
The clock in my battery/inverter is wrong
'Eco' Setting needs to be unchecked in the portal as well
The settings don't work independently & need to set in tandem with other settings for them to work

Based on everything I can see in the portal & descriptions of other peoples set ups around this board, I'm inclined to blame 2 or 3, and probably 3.

Yes, sorry. I was a bit quick to post there - I fell foul of the option when I was a newbie.

Point 4 - ECO mode will still discharge the battery to home (& car) outside of any timed discharge period if it is enabled.

Ah, that would make sense. Thanks

Not 100% sure how to turn that off via the app, but next time I get enough day time solar to last through the evening I'll give it a go via the portal.

Mayjest The other way to achieve what you're trying to do is to leave the Givenergy inverter in ECO mode all of the time. When you want to charge your car from grid, go to the Givenergy app, check what State of Charge (SoC) the battery is at (say 40%), go to System Modes and set a timed charge to start and finish when you want your car to also charge, but set your Charge up to to be the same as your battery SoC (the 40% already mentioned). In doing this, it will hold your battery at 40%, consume house load from grid and charge the car from grid for the timed charge duration. At the end of the timed charge period, the inverter will revert to ECO mode and support house load from battery.

Tim Hmm, that looks like a good way of doing the daytime 'charge now' ones. I know how long it takes roughly to charge, it's not the end of the world if a bit at the end comes off the battery or a bit extra is pulled off the grid if I get the timing wrong.

Not sure I'd be able to do the overnight one without manually setting it with a new updated percentage every night though. Was hoping for a bit more automation than that. I'm hoping for more of a 'set it and forget it' option without having to set up a Raspberry PI on my network, tbh

Mayjest Since it doesn't matter to you when you draw from the grid, you could just set your overnight timed charge window for both Givenergy inverter and PHEV to the same times and set your Charge to % to a generic value which leaves capacity to soak up any PV the next day. We do have a Time of Use tariff and set the Charge to % to 50% in late summer, rising to 65% now, and it will probably be set higher as the days shorten and PV reduces. Those are targets which enable us to get through to the next off-peak charge window if there is no PV to speak of but would enable top-up if PV is available. Often, there is no actual import overnight as the battery lasts through the period; the timed charge is there as insurance in case we have a large consumption in the evening, or the SoC collapses. For us the key is to avoid import outside the off-peak tariff. Off-peak for us is 4.5p/kWh compared to standard at over 39p/kWh. Timeshifting necessary consumption is a no-brainer.

Ah, that makes sense. Any day time car charges can be coordinated with manually reducing the discharge rate to 0 and putting it back when the car's done. I'm planning on doing a charge tonight to 60% as a test of how much we actually use during the day, so price out any available off peak tariffs. My current supplier (OVO) has suspended their and only offer their flat rate variable/price cap one.

Thanks for the help!