EV charging and battery BMS max discharge

[mortenmoulder]

Upcoming first time solar system and 'high' capacity battery owner here. I'm going to be installing a hybrid Deye 12 kW inverter with a 5 kWh LiFePO4 battery setup. I have no idea how the inverter setup works yet, so please bear with me.

I would like to charge my EV solely using solar energy, unless the sun is down and I have to buy it from the grid.

The 3 phase 11 kW EV charger (Easee Home) is just wired into mains power (not exactly sure how that works). If the solar energy is 0, but the car is charging, what happens? My guess is that the house battery kicks in, but since the EV charger is connected to the same circuit as the rest of the house, the EV gets charged using the house battery - which I don't want.

What do I need to separate those things? In an ideal world, I would like to be able to toggle this feature on and off, so that if I eventually get a really large house battery, and the electricity price skyrockets, I can use a few kWh of the house battery to charge the EV battery (in case of an emergency only).

Thanks!

 

[millsan1]

I'm having a hard time understanding all fo this, but since you are willing to do this manually, I would just set a schedule on your EV around when it can charge. I am fairly sure they all support this. So set your AC charging to only happen during daylight hours.

 

[houseofancients]

Upcoming first time solar system and 'high' capacity battery owner here. I'm going to be installing a hybrid Deye 12 kW inverter with a 5 kWh LiFePO4 battery setup. I have no idea how the inverter setup works yet, so please bear with me.

I would like to charge my EV solely using solar energy, unless the sun is down and I have to buy it from the grid.

The 3 phase 11 kW EV charger (Easee Home) is just wired into mains power (not exactly sure how that works). If the solar energy is 0, but the car is charging, what happens? My guess is that the house battery kicks in, but since the EV charger is connected to the same circuit as the rest of the house, the EV gets charged using the house battery - which I don't want.

What do I need to separate those things? In an ideal world, I would like to be able to toggle this feature on and off, so that if I eventually get a really large house battery, and the electricity price skyrockets, I can use a few kWh of the house battery to charge the EV battery (in case of an emergency only).

Thanks!

in general : 5 kwh in batteries ( and presumably 100A discharge limt) isn't ( by far enough to satisfy a 12KW deye ( 240A )

what you may want to do is hookup your charger to the GEN/AUX/Smart port of your deye, that way you can set parameter on when the charger can pull power/is powered on :

example : if Sun > 3,5 Kwh and SOC > 85 -> enable smart port

 

[mortenmoulder]

in general : 5 kwh in batteries ( and presumably 100A discharge limt) isn't ( by far enough to satisfy a 12KW deye ( 240A )

what you may want to do is hookup your charger to the GEN/AUX/Smart port of your deye, that way you can set parameter on when the charger can pull power/is powered on :

example : if Sun > 3,5 Kwh and SOC > 85 -> enable smart port

What do you mean by "isn't by far enough to satisfy"? I'm going to be using the new JK 200A BMS. Also those numbers are max - I'm assuming the minimum is around 0.

I'm not sure if the smart port is capable of 3 phase 11 kW. I doubt it is.

 

[mortenmoulder]

I'm having a hard time understanding all fo this, but since you are willing to do this manually, I would just set a schedule on your EV around when it can charge. I am fairly sure they all support this. So set your AC charging to only happen during daylight hours.

Horrible idea. If I get home late and the sun is down, I have to choose between charging the car (via grid) or turn off the house battery.

 

[houseofancients]

What do you mean by "isn't by far enough to satisfy"? I'm going to be using the new JK 200A BMS. Also those numbers are max - I'm assuming the minimum is around 0

Even a 200a BMS isn't enough.
200a x 51,2 = 10420 watts max through your BMS..
That is 2c on your cells, which I assume can do 1c sustained , if they are indeed automotive grade cells

These inverters will pull 240a when pulling 12k

.

I'm not sure if the smart port is capable of 3 phase 11 kW. I doubt it is.

It is capable of the total of the inverter..
So if you are pulling 11 kWh on the smart port, there is 1 kw left for the rest of the ports ( grid/load )

 

[jpwhit]

I think we're having trouble understanding the motivation behind your objective. I have two EVs, a fairly large solar and battery system. I don't really care if my EV's charge from battery vs the grid, why would I ?

If I have enough energy to cover 80% of my usage, then I have to buy the other 20% from the grid. Why would I care if that 20% goes to charging the EV or goes to running my HVAC?

 

[time2roll]

That 5kWh battery backup is good for maybe 15 miles if you turn the vehicle charging rate down to the minimum.

I recommend 24kWh to 48kWh battery with that inverter.

 

[Recovering EE]

I've got a 6000XP, PowerPro battery, and 6.4kW of PV.

I only charge our EV during daylight, and only L2 at ~2.9kW (12A at 240V). This allows me plenty of overhead, as I'm only using about half the capacity of my system for EV charging, and can run my (half) house on what's left.

Picking up about 10 miles of range per hour of charge is plenty. Right now it's manual, but I'm soon putting the EVSE on a 240V pool pump timer, so I can leave it plugged in to charge the EV to full over a couple of days.

I think you're trying to do far too much with what you've got.

 

[mortenmoulder]

I think we're having trouble understanding the motivation behind your objective. I have two EVs, a fairly large solar and battery system. I don't really care if my EV's charge from battery vs the grid, why would I ?

If I have enough energy to cover 80% of my usage, then I have to buy the other 20% from the grid. Why would I care if that 20% goes to charging the EV or goes to running my HVAC?

The motivation is that energy used to charge your EV in Denmark gets a $0.13 discount, because we essentially don't pay taxes when charging EVs.

Each kWh that my house battery charges up my EV will eventually cost me $0.13 extra, because that could otherwise be used on the house, that pays the full price including taxes.

 

[mortenmoulder]

That 5kWh battery backup is good for maybe 15 miles if you turn the vehicle charging rate down to the minimum.

I recommend 24kWh to 48kWh battery with that inverter.

Hence why I don't want to charge my EV at all using the house battery. That's the whole point of this post

 

[time2roll]

Hence why I don't want to charge my EV at all using the house battery. That's the whole point of this post

Yes I am not sure that was clear

Probably need to reduce the charging rate to about half the inverter capacity. Set the charge timer about 10a to 2p and plug in only on sunny days.