Electric Lunch Box
**Electric Lunch Box** is a portable lunch box with built-in heating or heat preservation functions, which is suitable for heating
food when going out, working in the office, or traveling. The following are its core principles, types, functions, and key points
for purchase:
I. Working Principle
The electric lunch box converts electrical energy into heat energy through **built-in heating elements**, and there are mainly
two heating methods:
1. **Resistance Heating**
- **Principle**: Utilize **resistance wires** or **PTC ceramic heating sheets** (Positive Temperature Coefficient) to generate heat,
directly heating the food inside the lunch box or the built-in container.
- **Features**: It heats up quickly (within 10–20 minutes), the temperature is controllable (usually between 50–100℃), and some
models support multi-level temperature adjustment.
2. **Steam Heating**
- **Principle**: After adding water to the bottom, steam is generated through heating to indirectly heat the food (similar to a steamer).
- **Features**: The food has a moist texture and is suitable for rice, steamed buns, etc., but water needs to be added in advance.
II. Main Types
| Type Type | Power Supply Method | Features | Applicable Scenarios |
| Plug-in Type | Direct plug-in (AC 100–240V) | High heating power (100–300W), no need for charging, but dependent on sockets. | Office, in-vehicle (requires a converter) |
| Rechargeable Type | Built-in lithium battery (DC 5–24V) | Portable, supports off-grid heating (battery life for 1–3 times), needs to be charged in advance. | Outdoor, commuting |
| Solar + Rechargeable Type | Solar panel + lithium battery | Environmentally friendly, suitable for long-term outdoor activities, but affected by sunlight, usually equipped with a charging function. | Camping, field work |
III. Core Functions
1. **Heating Function**
- Supports **constant temperature heating** (such as keeping warm at 65℃, boiling at 100℃), and some models can preset the time.
2. **Heat Preservation Function**
- Automatically switches to the heat preservation mode (40–60℃) after heating, keeping the food temperature for 2–6 hours.
3. **Portable Design**
- Lightweight (0.5–1kg), leak-proof and sealed, foldable power cord, and some come with tableware.
4. **Safety Protection**
- **Overheat protection**, **automatic power-off in case of dry burning**, **food-grade materials** (such as 304 stainless steel, PP plastic).
IV. Key Points for Purchase
1. **Capacity**
- Single serving: 300–500ml; Double serving: 600–1000ml. Choose according to your appetite.
2. **Heating Method**
- Plug-in type: Suitable for fixed places; Rechargeable type: Suitable for frequent outings.
3. **Battery Life**
- Pay attention to the **battery capacity** (such as 2000mAh) and **charging time** (fully charged in 2–4 hours).
4. **Material Safety**
- The inner liner should be marked with **304 stainless steel** or **food-grade PP** to avoid releasing harmful substances at high temperatures.
5. **Additional Functions**
- Detachable for cleaning, intelligent temperature control via APP, multi-compartment layering (separating dishes and rice).
V. Precautions for Use
1. **Avoid Dry Burning**: For steam heating types, add enough water, and for rechargeable types, avoid heating an empty box.
2. **Cleaning and Maintenance**: Clean it in a timely manner after heating, and do not immerse the circuit part.
3. **Battery Maintenance**: When not in use for a long time, keep 50% of the battery power to avoid overcharging and over-discharging.
VI. Examples of Market Products
1. **Morphy Richards Electric Lunch Box**
- Plug-in type, 300W power, 3-layer separation, supports steaming and heat preservation.
2. **Bear Rechargeable Heating Lunch Box**
- Powered by a lithium battery, 500ml capacity, adjustable temperature from 45℃ to 70℃, suitable for commuting.
3. **Sunflair Solar Lunch Box**
- Solar + USB charging, built-in thermometer, suitable for outdoor camping.
Conclusion
The electric lunch box solves the need for heating food when going out through **resistance/steam heating**. When purchasing,
it is necessary to comprehensively consider factors such as **usage scenarios** (plug-in/portable), **capacity**, and **safety
certification** to ensure both convenience and health.
