By Caspar | 03 August 2025 | 0 Comments
How to Choose a Lithium Battery Curtain Motor
How to Choose a Lithium Battery Curtain Motor
Why do we need to charge our lithium battery motors every two weeks? Frequent charging is inconvenient. Why do curtains stop opening after a while? These are common questions we encounter when purchasing lithium battery curtain motors.
When choosing a lithium battery curtain motor or tubular motor, you need to consider factors such as motor performance, Battery life, installation compatibility, smart features, and brand and after-sales service. EMLUX provides the following assistance to address customer questions.
๐น1. Motor Type and Power
โ DC Motor (Common): Low noise, low power consumption, and suitable for home use. Commonly used DC motors are 7.4V, 12V, or 24V, with a rated voltage of 1.5-3A.
For a motor with the same speed, reduction ratio, operating current, and magnetic field strength, the higher the power, the greater the torque.
Therefore, 25mm tubular motors on the market typically use 7.4V or 12V motors with planetary gears to achieve the appropriate speed and torque. By comparing two motors, we can intuitively determine their battery life based on their speed, operating voltage, and operating current.
For example, given the conditions, a 25mm tubular motor with a 7.4V 3200mAh motor (8.4A full charge) and an 11.1V 2800mAh motor (12.6A full charge) operating at both 1.1A and 25rpm will have a higher power output and, therefore, a higher torque. To achieve the same torque as the 11.1V motor, the 7.4V motor would need a planetary gearbox with a higher reduction ratio or a higher operating current.
To address this issue and maintain torque, the EMLUX EM25L-1.2/28 25mm tubular motor with a lithium battery uses an 11.1V three-series, one-parallel lithium battery pack, which delivers greater power output and a longer operating life than the 7.4V motor.
(2) Load capacity of EMLUX lithium battery tubular motor(EM25L-1.2/25)
(2) Load capacity of EMLUX lithium battery curtain motor
Ordinary curtains (within 4 meters): load-bearing capacity of 50kg.
Ordinary curtains (within 6 meters): load-bearing capacity of 35kg.
The following table is for reference only. We usually reserve 10-20% margin.
The longer the Electric curtain track, the greater the friction coefficient between the drive belt and the track. Therefore, the longer the track, the more friction the motor needs to overcome between the guide rail and the belt, and the weaker the motor load.
Recommendation: Measure the weight of the curtain (spring scale can be used) and select a motor with a load capacity slightly higher than the actual demand.
2. Battery life and charging
๐น(1) Battery capacity
โ Ordinary capacity (2000mAh-3000mAh): suitable for small curtains, battery life of 3-6 months (open and close once a day).
โ Large capacity (4000mAh-6000mAh): suitable for large curtains or frequent use, battery life of 6-12 months.
๐ Note: When choosing a lithium-ion battery curtain motor, battery life depends not only on capacity (mAh), but also on factors such as total energy (Wh), operating current, standby power consumption, and discharge efficiency. The following is a detailed analysis:
โ 1. Battery total energy (Wh) is more critical than capacity (mAh)
โ The battery life of a lithium-ion battery is essentially determined by total energy (Wh), not just mAh.
Calculation formula:
Energy (Wh) = Voltage (V) × Capacity (Ah)
For example:
A 7.4V 3000mAh lithium-ion battery has an energy of 22.2Wh (3.7V × 3.0Ah).
An 11.1V 2800mAh battery has an energy of 31Wh, but its actual battery life may be longer despite its smaller capacity.
An 11.1V 2500mAh lithium-ion battery has an energy of 27.75Wh (3.7V × 11.1Ah).
An 11.1V 4000mAh battery has an energy capacity of 44.4Wh, and its actual battery life may be longer despite its smaller capacity.
Purchasing Tips:
Prioritize the battery's Wh rating over just the mAh rating, especially when comparing batteries of different voltages.
For example, the EM25L-1.2/28 lithium battery tubular motor produced by EMLXU uses a 12V 2800mAh battery with an energy capacity of 33.6Wh. Compared to a 7.4V 3000mAh battery with an energy capacity of 22.2Wh, the 12V 2800mAh battery's actual battery life is approximately one-third longer than the 7.4V 3000mAh battery. Curtains and roller blinds are used in high-frequency environments, so frequent charging isn't recommended, right?
2. The Impact of Operating Current (Discharge Current) on Battery Life
The operating current of the curtain motor determines the rate at which the battery drains.
Under light loads (such as lightweight curtains), the current may be as low as 0.3A to 0.8A.
Under heavy loads (heavy curtains or stuck rails), the current may reach 0.5A to 2A.
Battery life estimation formula:
Theoretical battery life (hours) = Battery capacity (Ah) / Operating current (A)
Theoretical battery life (hours) = Operating current (A) / Battery capacity (Ah)
For example:
A 3000mAh (3Ah) battery with an operating current of 1A has a theoretical battery life of 1 hour.
If the battery is operated for 2 minutes (0.033 hours) per day, it can last approximately 30 days (1 hour ÷ 0.033 hours/day).
However, the actual battery life will be shorter because you also need to consider:
Standby current (see below)
Battery self-discharge (approximately 1%-5% per month)
Capacity loss due to low temperature/aging
Purchasing Recommendations:
Choose a motor with a low operating current (such as a brushless motor, which is more efficient).
Avoid overloading, which can cause a surge in current and significantly shorten battery life.
3. Impact of Standby Current (Quiet Power Consumption)
A curtain motor still consumes current in standby mode (connected to Wi-Fi/Bluetooth), potentially consuming more power than when operating.
Regular remote control models: Standby current is extremely low (<0.01mA), almost negligible.
Wi-Fi/smart models: Standby current may reach 5mA-20mA (due to maintaining a network connection). These models are not recommended, as the battery will drain in 2-3 days.
Standby Power Calculation:
Standby Power Consumption (mAh/day) = Standby Current (mA) × 24 hours
Standby Power Consumption (mAh/day) = Standby Current (mA) × 24 hours
For example:
A 12V 2500mAh curtain motor with a standby current of 0.5mA consumes 12mAh per day, or 360mAh per month!
A 2500mAh battery, excluding all the usage conditions described in this article, has a theoretical standby time of 8 months.
A 12V 4000mAh curtain motor with a standby current of 0.5mA consumes 12mAh per day, or 360mAh per month!
A 4000mAh battery, excluding all the usage conditions described in this article, has a theoretical standby time of 11 months.
Purchasing Recommendations:
Prioritize smart models using low-power protocols (e.g., Zigbee/BLE, which is more energy-efficient than Wi-Fi, used in the EMLUX YS-MT750L, EMD25L-1.2/28, and EMD35L-4.2/17). These motors have a power on/off switch and support sleep mode for long periods of inactivity, allowing for physical power shutdown.
4. Battery Capacity Does Not Equal Actual Dischargeable Capacity
A battery's nominal capacity (e.g., 3200mAh) does not equal its actual usable discharge capacity. The difference is typically determined by the following factors:
Voltage Droop Effect
As a battery discharges, its voltage gradually decreases (e.g., a lithium battery drops from 4.2V to 3.0V). When the voltage is too low, a curtain motor will experience reduced torque or even fail to start.
Result: The battery still has residual charge (approximately 5%-10%) that is not being used.
Discharge Efficiency Loss
Battery internal resistance, operating current, heat generation, and BMS (Battery Management System) power consumption contribute to energy conversion losses, resulting in actual usable energy typically being 85%-95% of the nominal value.
For example, the EMLUX YS-MT750 motor uses an 11.1V, 4600mAh battery. In a discharge test at 2A and 30°C, its actual discharge capacity is 4000-4500mAh. To avoid misleading consumers, the battery capacity marked on the EMLX nameplate is only 4000mAh. We only indicate the amount of energy actually available to the motor.
Suggestion: If you place an order with the manufacturer, please ask the manufacturer whether the battery capacity of this motor can be discharged to the power it indicates.
Ambient Temperature Influence
Low temperatures (<0°C): Lithium ion activity decreases, potentially leading to a 20%-50% decrease in capacity.
High temperatures (>45°C): Accelerated aging, resulting in faster capacity degradation with long-term use.
Thank you for your browsing. There is still a lot of professional information that we will elaborate on in the next article.we say no more at this time ,but we want you know more.
๐ Contact Us for Bulk/OEM Orders!
๐ง Email: [cindy@ysemlux.com]
๐ Website: [www.emluxi.com]
๐ WhatsApp: [+86 18688455797]
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