Automatic Solar Powered Car Charger Overflow Dump

[nettrust2]

I put together a very small MPP HV/LV2424 2400 Watt inverter, on 1300 watts of panels, which powers most 120v devices in house all day/night (fans/refrig/lights/computers) and often found my 4.3kwh lithiums filling up with my average 500 watt home load on sunny days.

This simple script turns on/off a smart plug to slow charge vehicle, ONLY when battery near full and/or big wattage surplus (gets MQTT messages from MPP/Voltronic inverter):



works well, car charger set at ~720 watts until I add more panels
(see blue line peaks below, only a few miles of range per hour when on, but better then wasting excess sun)
(sorry for the clouds, but the script handles it!)

 

[curiouscarbon]

looks good! charging EV extremely useful “dump load” up to 70-100kWh

do you experience any issues with it switching power off and on at the outlet? if it’s once every few hours, i figure it’s probably fine? no open source ability to negotiate charge rate as far as i am aware. would be amazing to negotiate lower charge rate when SOC low on house battery.

nice data graph??

must feel good to move based on magnetic fields induced by photons from sun fusion. fusion powered car. offsite fusion ?

 

[400bird]

I've been looking into getting this EVSE. It looks like you can adjust charger current via MPPT or an API. It can be adjusted as low as 6 amps (@240 volts) up to 48 amps.

OpenEVSE - Electric Vehicle Charging Solutions

OpenEVSE provides electric vehicle charging solutions worldwide based on SAE J1772 and IEC 61851 standards. Our experts provide components, software and services to accelerate the development of new charging technologies.

openevse.com

 

[400bird]

To OP, do you have any issues with cutting power to the EVSE? I'd expect th car to complain about that. If not, that's great news and a great dump load.

 

[nettrust2]

To OP, do you have any issues with cutting power to the EVSE? I'd expect th car to complain about that. If not, that's great news and a great dump load.

Tesla mobile charger can do 5a-12a @ 120v

I was stress testing my bigbattery today w/Tesla as sink:

 

[400bird]

Tesla mobile charger can do 5a-12a @ 120v

I was stress testing my bigbattery today w/Tesla as sink:

View attachment 66225

Is there any way to adjust that outside of manual adjustment either on the screen or using an app?

It looked to me like you're cutting power to the EVSE, not actively adjusting charge power? I'm not 100% sure because it looks like a smart plug and simple on/off control in the code. But, the blue charge current has multiple steps (400ish watts, 200ish, and 1.25k)

 

[nettrust2]

Is there any way to adjust that outside of manual adjustment either on the screen or using an app?

It looked to me like you're cutting power to the EVSE, not actively adjusting charge power? I'm not 100% sure because it looks like a smart plug and simple on/off control in the code. But, the blue charge current has multiple steps (400ish watts, 200ish, and 1.25k)

The load power graph in my post #1 is shared w/other appliances in my house, hence the variability, Graph in my post #5 is dedicated to just the Tesla, and fixed at 5 or 6 amps, I"ll likely turn it higher in the future, and may research their new current-control API, which would help for larger off-grid systems. Openevse looks interesting, but every Tesla comes with the mobile charger, which can utilize up to 1440 watts.

 

[400bird]

Yeah, every EV includes a little 120v (in the US) charger. It's nice that Tesla let's you easily adjust the charge current. On my Bolt I've got to choose either 8 amps or 12 amps.

With OpenEVSE I should be able to match excess solar and put it into the car, then charge the home battery once the car is full.

 

[curiouscarbon]

so you’re cutting the power at the wall?

 

[nettrust2]

so you’re cutting the power at the wall?

I'm only using smart plug for on/off, and Tesla app for current selection, which seems to allow varying between about 500-1400 watts (just under the amperage specified in their app (5a-12a), if my metrics are correct).

 

[nettrust2]

Make sure smart plug can handle the charge current. Many are 15 amp, some are 20, some are 10. Verify with your electrician.

 

[nettrust2]

Just to update, using Tesla new charging_amps setting in API, I can track solar power very tightly, and assure house batteries are up to desired voltage at all times (blue is load (Tesla), yellow is solar power):



cli.py -e *car-email* -w -a CHARGING_AMPS -k charging_amps=$1

 

[curiouscarbon]

awesome graph!

thanks for sharing, very interesting usage

may i ask for a reference to the API documentation you used?

 

[nettrust2]

credits to tdorssers: https://github.com/tdorssers/TeslaPy/blob/master/cli.py

 

[curiouscarbon]

thank you ?