What is Low Current Charging in Power Banks? (a.k.a Trickle Charge)

Some power banks do not charge devices that require low voltages. Gadgets such as fitness bracelets, smartwatches, Bluetooth headphones, etc., are the most common examples of such low-power devices.

In this article, I’ll explain the reason for this issue, and talk about some power banks that offer a way around it.

Let’s begin.

What is the Trickle Charging Mode in Power Banks

Quick Answer
Low current charging, also known as trickle charging, is a feature found in some power banks designed to safely charge devices that require a lower current. This mode delivers a smaller amount of current (typically around 1A or less) compared to the standard charging mode. By providing a gentler, more controlled flow of power, trickle charging ensures that these small, sensitive devices are charged safely and efficiently, without overloading their batteries.

Not all batteries are the same, and they all require different amounts of current to recharge them. Even though power banks can usually charge batteries of all smartphones irrespective of their specific capacity, they are not always suitable for low-power devices like Fitbit bracelets, Apple Watch, BlueTooth headsets, etc.  

smartwatch trickle charge

This is because these devices are equipped with a very tiny battery that requires a very low current to recharge them. The process of charging these low-powered devices with tiny battery packs using a very weak current is known as low-current charging.

Another term that you’ll see people online use to describe this process is “trickle charging“. Although trickle charging can refer to other things as well, in relation to power banks, we can use it interchangeably with “low current charging“.

Understanding the Circuitry Behind Trickle Charging

While trickle charging is a handy feature for charging small devices, the technology behind it is quite fascinating. Here are the two main technical components that enable low-current charging:

Voltage Regulation and Current Control

At the heart of trickle charging lies the principle of voltage regulation and current control. Power banks equipped with this feature have internal circuitry designed to maintain a constant voltage output while significantly reducing the current. This is crucial because small devices like Bluetooth earpieces or fitness trackers require a much lower current for safe charging. The power bank detects the connected device’s requirements and adjusts its output accordingly.

Safety Mechanisms

Safety is paramount in electrical devices, and power banks are no exception. When it comes to trickle charging, power banks incorporate various safety features to prevent overcharging and overheating. These include thermal sensors and voltage regulators that ensure the power bank and the connected device remain within safe operating temperatures and power levels, thereby extending their lifespan and maintaining battery health.

Why do Some Power Banks Fail to Deliver Low Current Charging?

There can be several different reasons why a power bank might not be able to charge low-current devices: 

Minimum Current Threshold: Power banks often have a minimum current threshold. This means that if the device connected to the power bank doesn’t draw a certain minimum amount of current, the power bank may not detect it and might shut off to save power. Small devices like Bluetooth earphones, fitness bands, or smartwatches may not draw enough current to exceed this threshold, causing the power bank to shut down.

Lack of Trickle-Charging Feature: Some power banks may not have a trickle-charging feature, which is a mode that allows the power bank to deliver a very low current. This mode is useful for charging low-powered devices with small batteries that require a low current. If a power bank doesn’t have this feature, it may not be able to charge such small devices effectively.

Insufficient Power Management: Power banks with poor power management may not be able to regulate the power output effectively to cater to devices with low power requirements. They are designed to charge more power-hungry devices like smartphones and tablets, so they might not be able to deliver the steady, low current needed by smaller devices.

Incompatibility: In some cases, there could be compatibility issues between the power bank and the device, especially if the device has unique power requirements or a proprietary charging system.

How to Enable Trickle Charging in Your Power Bank

Some power banks have a built-in low-current charging feature, but you will need to enable it first. Follow these steps to enable it. 

  • Connect one end of the data cable to the low-current charging device of your preference and the other end to the USB-A port of your power bank. 
  • To enter the trickle charge mode, double-press the power button on your power bank. (This mode will be active for two hours, and your power bank will return to regular charging mode after that. You can also press the power button again to quit it manually)
  • The LED indicator on your power bank will flash in a sequence, indicating that the trickle charging mode is currently active. You can now charge your device.
  • Once your device is charged, it is recommended that you manually exit the low-current charging mode. If your device is not charged after two hours, double-press the power button again to re-enter low-current charging mode.

GoalZero Sherpa Charging Ports

Troubleshooting Common Trickle Charging Issues

Despite the convenience of trickle charging, you might sometimes face challenges in getting it going. Here are some ideas that might help you troubleshoot some of the most common issues encountered while using the trickle charging feature.

Power Bank Not Entering Trickle Mode

If your power bank doesn’t seem to switch to trickle charging mode, first ensure that your device is compatible with this feature. This should be clearly stated in the user manual. In case you don’t have the user manual anymore, you should be able to easily find it on the internet by searching after the exact power bank model name and adding the keywords “user manual” and/or “PDF”.

Some power banks require a specific sequence of button presses to activate trickle charging – consult your power bank’s manual for guidance. If the issue persists, check the health of your power bank and the integrity of your cables.

Device Not Charging Properly

When a device doesn’t charge correctly in trickle mode, first check the cable connections. Loose or damaged cables can disrupt the charging process. Also, verify that your device’s power requirements align with what your power bank’s trickle charge mode offers. Some devices have specific needs that might not be compatible with standard trickle charging outputs.

Power Bank Shuts Off During Trickle Charging

This is often a safety feature to prevent energy waste when the power bank detects no substantial power draw. If your device is very low on power or has a very small battery, the power bank might not recognize its power draw. Try reactivating the trickle charge mode, or if possible, start charging when your device has a slight charge already, to ensure the power bank detects it.

Frequently Asked Questions

Here are answers to the most frequently asked questions about low current charging in power banks. 

Is it Safe to Charge Low-Current Devices With a Power Bank?

It is safe to charge a low-current device with a battery charger only if it is designed to charge such devices. Most power banks are not compatible with low-current devices and treat them just like any other smartphone. This may cause them to send a high-intensity current which can damage your device. 

Why Do Power Banks Charge Low Current Devices for Five Seconds and Then Stop?

Most power banks have an inbuilt power detection feature where they send out a charge to the device they are supposed to charge to read their current status and charge holding capacity. When you connect a low-current device to a battery charger, it sends out a charge for a few seconds and then stops because it is not able to detect the presence of any battery due to its small size. 

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