FoxESS Community - Owners & Installers Forum

All,

I expected this to be a common topic, as I didn't expect my situation to be so unique. Search is limited here as you can't search well for charging ev, or electric vehicle says its too common, so I may be missing the name for it, but here is my situation.

System:
Inverter KH9.9
Battery 42.3kWh
Solar 6.6kW

My OVO EV plan has a FREE (yes totally free) 3 hours of the day 11am-2pm and a super off peak rate of 8cents for midnight to 6am.

I am trying to work through how to utilise as best as possible the Free period (I can charge 30kW in that period) regardless of solar and then how to not drain the battery during the super off peak while charging the EV.

I think I'm straddling the release of v2 of the software, as things I could do yesterday on the app, I can't today, but here is my current Mode Schedule and my thought pattern
Let's start at the free period
11am - Force Charge as high as it will go.
Doesn't matter if there is other usage as everything is free
2pm - Set to Self use - pull from PV first and excess can charge battery, if no excess, then use battery instead of grid.

Midnight - car is set to charge
Set to Backup with a 30% Backup SOC.
My expectation is
If SOC >30% (unlikely but possible based on my usage in summer) Some discharge from battery to car will occur, then it will stop at 30% and just pull from grid at super off peak rate
If SOC <30% will charge to 30% at super off peak rate

Car will charge till it reaches it prescribed SOC or until 6am when it stops.

At 6am, my goal would be car is charged, and battery is at 30% or higher (on nights where the car doesn't need to charge)

And that would give me the ability to get to 11am with PV and battery use and not any expensive grid use.

The goal is minimal use of grid (not zero) when its paid, even if cheap. But avoiding as much as possible draining battery to car.

Are there better options?

Thanks in advance.
K

The Free period and after 2pm looks good,

Nothing wrong with your midnight backup workmode would work but my initial thought with such a low tariff is would it not be easier to set a force charge with a lower charge rate (and/or with a lower charging cut off soc).

Thanks for the response Dave.

Backup didn't do what I expected. It just didn't let the battery do anything... which was weird, as the doco says otherwise.

All usage was direct from the grid and SOC stayed at (38%) for the 6 hours.

I did consider a small force charge, but the idea was it would use 'some' of the battery. Most nights I don't plug the car in, so I had hoped that most nights, it would just use the battery overnight, and thus have zero use, even if cheap.

I have enough battery to get through 24 hours, and charging in the free period, brings me back to 90+% every day.

I'll keep playing, but glad to know I'm kinda on the right track

Last time I tested Backup, it held the battery SoC and battery in idle. It was basically waiting for a power cut to happen, so it keeps pulling power from the grid to supply load.

Wraith wrote: ↑Tue Feb 10, 2026 4:09 am Backup didn't do what I expected. It just didn't let the battery do anything... which was weird, as the doco says otherwise.

All usage was direct from the grid and SOC stayed at (38%) for the 6 hours.

Backup is hold battery discharge and maintain, i.e. when there is no solar the battery will not be used at all and all home load will come from the grid - when there is PV available the battery will not be used and will charge from excess solar above house load.

Thank you Dave for the extra bit of clarity on the Backup mode.

Thanks Dave. It behaved how you described. Which is fine. But I had hoped if the battery was above the target SOC it would pull from the battery and then hold once it discharged to that SOC.

I have implemented your advice of just force charge slower.

This does end up being 'good' on days I charge the car, but does mean I am charging when I don't need it, and even at a cheap rate, its a cost.

A minor gripe, $2 of spend per day, is $700+, where its possible that could be only the days I charge.

for now, I can change the mode if I am really keen to save the $2. But I know I wont