Limiting my GivEnergy battery charge to 80%

I've probably missed the setting to do this but in a nutshell I'd like to stop charging my GivEnergy at 80% rather than 100%. Let me explain why ...

Firstly, I'm working on the assumption that the GivEnergy batteries have a charging curve where they take longer to charge once the charge level is above 80% and that regular charging batteries to 100% is not good for them either. If either of those are incorrect then the rest of this may not be relevant.

We've got Octopus Go which gives us 4 hours of cheap electricity (00:30 - 04:30) and we use that to charge our house batteries (a Gen 1 5.2 kWh and a Gen 2 8.2 kWh) via our Gen 1 3 kW invertor. At the same time I'm also partially charging my EV via our Hypervolt charger.

What I'd like to do is to charge the home batteries to 80% and then for any excess solar to go into the car.

At the moment it all works fine but the home batteries have to charge to 100% before the invertor will send the excess to the grid which is where my Hypervolt charger steps in and grabs it. If my assumption is correct (that the home batteries slowly charge above 80%) that means that the Hypervolt would get any excess power later than it would otherwise would.

So, can I limit the home batteries to charge at just 80% ? By the way, if it's not possible to do it within the GivEnergy control panel I do have Home Assistant running as well with the GivEnergy integration.

Thanks in advance ...

I do not know of a way to do this. However my understanding is it is only an issue leaving batteries at 100% for extended periods because house load will take over after your charge period you should not have an issue, simply they will not be at 100% for long. Example for me my batteries are about to hit 100% and will stay at 100% until I get home at 7pm, so 6 or 7 hours isn't going to hurt them. The new firmware also does slow the charge at the topend. Right now at 96% charge is only 1.1kwh

I believe that the bigger batteries already have a buffer, so that 100% is not "true" 100%. So slowdown may not be as pronounced. I think that the GE battery chemistry is different from that of cars, and they don't mind sitting at 100% so much.

And I get the impression it is a good idea to charge to 100% occassionally (as with a car) to allow the BMS to keep track of the endpoints - voltage curve is very shallow, so it's hard for it to know exactly how much charge there is.

But even if the battery charging did slow down, wouldn't the excess just go to the grid anyway, where your hypervolt can pick it up. (There is still the problem that it has to reach 1.5kW before car can start charging).

Yeah I believe it's Lithium and Potassium battery technology.

TX200 LFP

Lithium Iron Phosphate
LiFePO4 is the chemical make up

I forgot the Iron. (Insert joke about blokes and not knowing how to Iron)... 😁

Pidea With HA you can simply adjust the Battery Charge rate. From about April (when there usually more than enough solar to fully charge the batteries during the day), our batteries are set to charge at <1kW so we start exporting earlier in the day, and start EV charging earlier too.

If you want to stop battery charging at 80%, simply reduce Battery Charge Rate to zero, using HA, when the SoC > 80%. Don't forget to reset it to >0 when SoC < 80%.

Tim Thanks for the reply Tim, what you're doing sounds exactly what I want to achieve.

I had a quick look in HA but can't see an obvious way to build an automation which says:

if PV_power is greater than 2000:
set battery_charge_power_limit = 80%
else:
set battery_charge_power_limit = 100%

How did you do it ?

Or are you manually changing the Battery AC Charging value within HA ?

Tim with the new inverter/BMS I still have zero = 300 watts charging. Do you see the same ?
Pidea if you want to do what Tim was suggesting, you are setting the rate of battery charging, not the maximum battery soc.
So what you automation should look like is..
if battery_remaining_capacity > ( whatever value you want)
set battery_charge_power_limit = 0
else:
set battery_charge_power_limit = 2600

justpassing else:
set battery_charge_power_limit = 2600

@Pidea or set battery_charge_power_limit = 900 for a long lazy charge.

justpassing with the new inverter/BMS I still have zero = 300 watts charging. Do you see the same ?

I've never actually set it to zero! It's all fully charged now but I'll have a go tomorrow morning.