Thermal Protection
Like all modern smart devices, including solar inverters and EV chargers, zappi includes built-in thermal protection to ensure safe operation. Under certain conditions, the charger may temporarily reduce its charging power if internal temperatures approach predefined safety thresholds. This behaviour is intentional, compliant with IEC 61851, and designed to protect both the user and the hardware.
Different manufacturers take different approaches to thermal management. Some prioritise maintaining peak output for as long as possible, while others apply earlier, controlled reductions to protect long-term reliability. Managing operating temperature doesn’t just ensure safety; it also reduces long-term thermal stress on internal components, helping extend the service life of the zappi and its electronics. myenergi’s approach focuses on stable charging, component longevity, and predictable behaviour in high-temperature environments.
What some users observed
Following reports from some customers of unexpected reductions in charging speed during warmer conditions, myenergi conducted extensive laboratory testing and real-world monitoring across multiple hardware revisions and ambient temperature ranges.
This testing confirmed that earlier firmware versions prioritised conservative thermal margins. While charging speed was reduced, the unit was not overheating at any point. Instead, it was stepping down as a precaution while still operating comfortably within safe temperature limits.
In these earlier versions, thermal throttling could present as a “saw-toothed” charging profile under elevated temperatures, where the charge rate would step down and recover repeatedly rather than remain stable.
Firmware Update v5.557
Firmware Update v5.557, released in 2023, significantly improved zappi’s thermal management behaviour. The update refined how throttling is applied, prioritising stable output power rather than repeated step-down and recovery cycles.
Extensive laboratory and real-world testing confirmed a clear improvement in thermal response:
Removal of saw-toothed charging behaviour
Stable output power at elevated ambient temperatures
Increased total energy delivered to the vehicle over time
During testing at zappi’s maximum declared rated ambient temperature of 40 °C, units running v5.557 maintained stable output while remaining within certified thermal and electrical limits. Testing included units exposed to prolonged heat, high utilisation, and repeated daily charging cycles.
At an ambient temperature of 40 °C, controlled charge rate adjustments were observed, typically around:
15 % when charging single-phase at 7 kW
26 % when charging three-phase at 22kW
Even at 40 °C ambient, this controlled reduction delivers more total energy to the vehicle in a shorter time compared to earlier firmware behaviour.
Importantly, zappi’s underlying safety limits did not change. Firmware v5.557 refined how power is managed at high temperatures, not when protection is applied.
Note: Exposure to direct sunlight may have an increased impact on internal temperatures
As with any electrical appliance, installing an EV charger out of direct sunlight where practical supports optimal operation. Many EVs will also reduce their own charging rate in high temperatures, so parking in the shade helps both the vehicle and the charger perform at their best.
Updating Firmware
If you require guidance on how to update firmware on zappi, please see this article: Updating zappi v2.1