Issues where the system behaviour, as observed on the energy flow of the Fox Cloud app, is counter to what you would expect to see given the reported circumstances, might point to incorrect settings or a firmware mismatch. However, if you only observe this on rare occasions, it could be due to the data polling delay.

The data collected on the Fox Cloud is communicated at 5-minute data polling points – so this is just a snapshot; so if you were to compare the cloud data directly, say, with readings on the inverter screens, they likely will not match.

The overall energy flow for the whole site is based on data captured once every 5 minutes; in other words, you are seeing an accurate overall picture for the whole system at the point the inverter polls its data. There is the potential for very occasional data anomalies owing to the response time to state changes. For example, if you suddenly apply a heavy load in the property, it may take the inverter 1-2 seconds to respond to that change. If data polls at the precise moment the inverter is reacting, the cloud display may appear to show an anomaly – e.g., it might indicate that energy is being imported rather than discharged from the battery. In reality, this may have adjusted within half a second, but if the data is captured at that point, the customer will see an apparent anomaly for up to 5 minutes. This happens rarely, but it is important to understand in order to reassure customers who raise this query.

The overall (full system) energy flow provides a full system picture, but again, this is a snapshot once every 5 minutes. Fox plans to increase the frequency of polling points with the release of new cloud updates over the coming months, so communications will become more regular at that time.

Credit: https://fox-ess.tech/why-am-i-importing-energy-from-the-grid-when-batteries-are-charged-other-app-anomalies/

No, Fox WiFi dataloggers transmit on the 2.4 GHz band only. Due to their longer wavelengths, 2.4 GHz signals travel farther and can penetrate walls and floors more effectively than 5 GHz signals, which is critical when inverter locations (e.g., loft space and outbuildings) are often external to the main living space.

All routers supplied by UK internet service providers will provide dual-band functionality – we're not aware of any exceptions at this time; however, in some cases, routers may be shipped with 2.4 GHz disabled by default. To enable this option, you need to access the device settings. Please refer to the provider's instructions for accessing the router admin settings. Please note that Fox ESS support teams cannot assist with this process, as it requires access to a 3rd-party device to adjust settings that can only be carried out locally.

Credit: https://fox-ess.tech/will-the-datalogger-work-with-5-ghz-band/

If you encounter an issue with the data on the app not updating and appearing to have frozen at a particular point in time, we suggest accessing your system at foxesscloud.com (using same username and password) to verify that you are seeing data updates on this platform. If data is populating, this may point to an issue with your device or app install.

The first step would be to clear the cache for the app on your device, or simply reinstall the app. Guidance as follows:

Clearing App Cache on Android & iOS

Android (Varies by Version & Manufacturer)

1. Open Settings → Go to Apps or Apps & Notifications.
2. Find and select the app you want to clear the cache for.
3. Tap Storage & Cache (or just Storage).
4. Tap Clear Cache.

iOS (Only Option: Reinstalling)

iOS does not allow direct cache clearing. Instead, you can:

1. Offload App (keeps data but removes cache):
   - Settings → General → iPhone Storage.
   - Select the app → Tap Offload App → Reinstall.
2. Fully Delete & Reinstall (removes all app data):
   - Settings → General → iPhone Storage.
   - Select the app → Tap Delete App, then reinstall from the App Store.

If you are also not seeing data populate on the web browser version at foxesscloud.com; this may point to a connectivity issue. We would suggest power-cycling your router in the 1st instance, failing that we would re-paring your dongle (assuming it is wifi) to your router. There is no repairing required for LAN or 4G connected devices, so a loss of comms in this scenario would require further investigation.

Credit: https://fox-ess.tech/app-not-updating-despite-system-being-online/

Battery Chemistry

Fox ESS utilise cobalt free LiFePO4 cells across its range of battery storage products (the most stable of all battery chemistries), providing high chemical stability and thermoelasticity. The phosphate cathode material in LiFePO4 cells is notably less susceptible to thermal runaway than other lithium-ion battery chemistries.

Operating Temperature Range

Charge: 0°C – +55°C

Discharge: -10°C – +55°C

These ranges represent the absolute maximum temperature range; however certain derating and protection measures will deploy within this range as detailed below.

While batteries can operate within the defined range detailed above, protection measures to derate the charge & discharge rates will be applied.  See Performance Management.  In addition, the battery may enter Power Reserve Mode (detailed below) which will temporarily raise the minimum Soc during periods of extreme cold.

How is temperature monitored?

The battery BMS collects temperature readings from internal sensors and this is communicated to the inverter.

What happens is the temperature falls below the defined minimum?

Should the temperature fall slightly outside of the defined range, the battery will enter a dormant (hibernation state) and remain idle until the temperature falls within the operating range.  It is important that batteries are located in an environment where there is no prolonged exposure to extreme cold outside of the operating ranges as defined.  This would not apply to batteries with internal heating where internal temperatures are regulated.

Are there any self-correcting measures?

For batteries that don't include internal heating functionality, there will some measures deployed in periods of prolonged exposure to low temperatures.  The battery BMS will monitor the battery SoC (state of charge) and will use small amounts of PV or grid energy at temperatures below 5°C to maintain a healthy state of charge – this process will, in turn, help raise the internal battery temperature.

Power Reserve Mode

Power Reserve Mode (PRM) activates when the minimum cell temperature is <3°C and the SOC is <60%, the system deploys protection measures (low-temperature power reserve mode), and the current limit value of discharge is temporarily reduced to 0, and the discharge is prohibited; when the SOC is >=65% or the minimum cell temperature increases to 5°C and above, the system exits the low-temperature power reserve mode, and the discharge is restored to normal.  This is a protective mechanism for battery health and will clear when the temperature rises.

Please note, for EP5 and EP11 batteries, it is possible to alter the logic outlined above to reduce the SOC threshold deployed in PRM in certain instances. This would require special firmware which can be applied on a case by case basis.

Performance Management

Exposure to temperatures at the upper and lower limits of the operating ranges will result in reduced rates of charge and discharge and Power Reserve Mode will activate to temporarily raise the minimum SoC.

Why do charge/discharge rates reduce in low temperatures?

Reducing the charge rate at low temperatures is a deliberate protective measure by the charger/inverter to:

• Avoid lithium plating.
• Compensate for increased resistance and reduced electrolyte performance.
• Prevent long-term damage to the battery.
• Ensure compliance with the BMS and maintain safe charging conditions.

This behaviour extends the battery’s lifespan and ensures reliable performance in challenging environments.

Derating at low/high SOC

At very low or high states of charge, charge and discharge rates are automatically reduced to protect battery health and ensure long-term performance. When the SOC is extremely low, the battery management system (BMS) limits charge rates to prevent excessive stress on the cells, which could lead to accelerated degradation. Similarly, at very high SOC, charge rates are throttled to avoid overvoltage conditions and excessive heat buildup. This intelligent control mechanism helps maintain battery efficiency, prolong lifespan, and enhance overall system safety.

It is important to note, such measures are not specific to Fox. They are driven by the battery chemistry and therefore deployed across the industry.

Efficiency impact at low temperature

LFP (Lithium Iron Phosphate) batteries maintain their rated usable capacity across a wide range of temperatures. However, at low temperatures, chemical reactions inside the battery slow down, and internal resistance increases. This leads to a temporary reduction in system efficiency — meaning not all of the stored energy reaches the connected loads.

In practical terms, the battery still charges to full capacity and discharges down to its minimum state of charge, but more energy is consumed internally (as heat or voltage drop), so users may see less delivered output.

This is a normal characteristic of all lithium-ion battery systems and will return to normal performance as the temperature rises.

Fox ESS has recently updated the Fox Cloud app interface. Following this update, the previous "Quick Setting" or battery icon shortcut to enable force charging is no longer available.

Force charging must now be configured using the Mode Scheduler function within the app.

While this may initially appear more complex, once set up correctly, it provides greater control over how and when your battery charges from the grid.

Navigate to Mode Scheduler

From the app home screen:

• Select Work Mode
• Choose Mode Scheduler
• Select Add Schedule
• Choose Forced Charge

Note: Screen layout may vary slightly depending on inverter size, firmware version and system configuration.

Important Settings Explained

SoC = State of Charge (Battery capacity shown as a percentage).

System Min SoC

This should normally be set to 10%.

This allows the battery to discharge down to 10% before stopping, enabling maximum usable capacity.

Exception: If you have a Gateway or manual changeover switch and are expecting a power cut or storm, you may temporarily increase this to 40–50% to retain backup power.

System Max SoC

This should typically be set to 100% to allow full charging when required.

Charging Cut-off SoC

Set to 100% if you want the battery to fully charge from the grid.

If you wish to leave capacity available for solar generation later in the day, reduce this accordingly.

Charge Power From Grid

This setting must not exceed your inverter's maximum output rating.

• 3.68kW inverter → set no higher than 3680W
• 5kW inverter → set no higher than 5000W
• 6kW inverter → set no higher than 6000W

Setting a value above your inverter rating will not increase performance and may cause operational issues.

When Should You Use Forced Charging?

• During low overnight tariff periods
• When preparing for forecast poor solar generation
• Before an expected power outage (if backup configured)
• When grid pricing makes off-peak charging cost-effective

This guide is accurate as of February 2026. Fox ESS may update the app interface in future versions.