Have you ever tried to charge your electric vehicle using only excess solar power and then found that it falls asleep while waiting for the sun to cooperate? For some electric vehicles like the BYD Dolphin, this is more than just a minor inconvenience – it’s a frustrating error that stops charging completely. Imagine plugging your car in and expecting it to receive energy from your solar system. Instead, it shuts off after a few minutes without power, requiring you to reset it manually.
This is what happened to SolarQuotes reader Gregory. Gregory has a SolarEdge electric vehicle charger that he tried to set up to use excess solar power to charge his BYD Dolphin.
A problem arose because the Dolphin went into sleep mode after 15 minutes without excess solar power to charge. As a result, the charger displayed “Waiting for Auto” and would not start charging until Greg either:
- unplugged the charging cable and plugged it back into the car,
- started the BYD app,
- or opened a car door.
According to New Zealand electric vehicle charger manufacturer Evnex, the BYD Atto 3 has the same sleep problem, but Evnex has found a clever workaround.
A spokesperson for BYD’s Australian distributor EV Direct told me:
“Our engineers have informed me that sleep mode for the ATTO 3, SEAL and DOLPHIN models does not correlate with the minimum charging power. The vehicles check to see if a signal is detected, and if no signal is detected, the vehicle goes to sleep.”
This wasn’t a very detailed answer, but luckily BYD customer service Gregory explained the situation much better:
“To ensure proper charging of the vehicle battery, it is important to maintain a constant supply of energy. When the voltage falls below 1.5V, the vehicle automatically enters “sleep mode”. In this state, it cannot detect energy levels below 1.5V and will not accept a charge until woken up again. To wake the vehicle, simply lock and unlock it.”
“For those using a solar charger with ECO mode selected (which uses excess solar energy to charge the car), please note that the vehicle will also enter sleep mode when no excess energy is available as the voltage is below 1. 5 V drops.” .
“Ensuring a constant supply of energy and properly charging the vehicle optimizes its performance and avoids unnecessary interruptions.”
Good news: Zappis keep your car awake
Readers should not worry that all electric vehicles have trouble falling asleep while waiting to be charged by excess solar energy.
Double EV homeowner Evan (Volvo XC40 Recharge) and Beau (Polestar 2) told me that they are keeping their Zappi charger:
“In Eco+ mode that turns it off completely when solar power runs out or house load exceeds excess. Doesn’t seem to be a problem, it can sit idle for hours and then turn on as soon as there is solar power“.
BYD Seal owner Campbell agreed and told me he has one too The Zappi charger is set to ECO+ mode.
“So far I have not noticed any problems with the paused/stopping charging process on my Zappi… I also sometimes use ECO mode (not ECO+), which always provides 1.4 kW base load to charge the vehicle and increases output when excess solar energy is available.”
“This is useful on intermittently cloudy/sunny days as it prevents the EV charger from frequently pausing charging, and it also prevents it from pausing when falling just a few hundred watts below the 1.4kW charging limit becomes. (e.g. export 1.2kW back to the grid while I could only pay 5 cents per hour for that extra 0.2kWh of energy).”
Teslas stay awake too
Finn charges his Tesla with excess solar power and has had no issues with his EV falling asleep while waiting for a charging session to begin.
Why do electric vehicle chargers require at least 6 amps per phase?
Campbell’s mention of the Zappi Eco mode piqued my interest and I researched why it was set to 1.4kW. It turns out that 1.4 kW is equivalent to 5.83 amps (so about 6 amps) in a country like Australia, where the residential power supply is 230 volts.
6A x 230V = 1.38kW
The Germans are known for their precision and love of rules, so I trust SMA when they say:
“The minimum charging current of the EV charger is 6 A. According to the IEC 61851 standard, a lower value is not permitted.”
Zappi competitions:
“According to the electric vehicle charging standard, the minimum charging current is 6A (which is about 1.4 kW for single-phase electric vehicle charging). So if you have less than 1.4kW of excess generation, the additional electricity must be sourced from the grid.”
“In Eco mode, the EV should start charging as soon as it is connected to the grid and continue charging at 1.4 kW (or more if there is a backup generation) until the EV is disconnected from the grid or the battery is full.”
What to do if your electric vehicle goes to sleep while waiting to charge?
So if you have an electric vehicle and solar charging doesn’t work because your car gets drowsy, there’s a workaround: charge it with at least 1.4 kW.
This should keep your electric vehicle awake and charging up to the set limit without any glitches.
Additionally… the advice from resident SolarQuotes Sparky Anthony is:
“It’s not good to turn something on and off too often. Cars often have large contactors/relays that switch the main module’s voltage to various components, and they have a specific lifespan. I think the BMS might have a little difficulty estimating the state of charge if things aren’t going well when charging.”
I’m no lightning freak, but it seems sensible to avoid unnecessary wear and tear on the electronics of car and home chargers by providing at least 6 amps (per IEC 61851 standard) from a home electric vehicle charger during the scheduled home charging time.
This wayBoth the EV and the home charger do not send start/stop charging signals every time clouds reduce solar power or someone turns on the kettle. And If you’re charging during the day, most of the electricity you’re drawing from the grid probably comes from solar anyway.
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