FAQs about XTAR 4150mWh AA Li-ion Battery

What is the internal structure of the 1.5V AA 4150mWh battery?

The 1.5V AA 4150mWh rechargeable lithium battery utilizes a 3.6V 14430 battery core. It is internally integrated with an efficient charging and discharging management dedicated chip, using 1.5MHz synchronous rectification buck discharge. It has built-in protections for over-discharge, short-circuit, and over-temperature, and the indication of charging, full, and short circuit status. When the battery core voltage is approximately 3.15V, the battery output voltage automatically drops to 1.1V. The battery size is the same as 14500.

The built-in 3-in-1 smart chip refers to the integration of three chips: the charging management chip, the synchronous rectification buck management chip, and the lithium-ion battery protection chip. These three chips are packaged together.

Is this type of battery safe？

Yes. The rechargeable 4150mWh AA lithium battery is equipped with a built-in 3-in-1 smart chip. It enables intelligent charging and discharging management and multiple protections of over-discharge, short circuit, over-temperature, and more. Also, it has LED indicators for timely charging, full charged, and discharge abnormal indication. At the same time, the lithium battery is anti-leakage, and anti-corrosion.

What’s the difference between mWh vs mAh?

Battery capacity (mAh) defines the amount of charge stored by the battery. It is the maximum power that the battery can be used, more useful for the battery runtime. Battery energy (mWh) is the value of mAh multiplied by voltage, which determines what kind of device the battery can drive. It is a dynamic concept. It is the actual power of the battery in a certain state. Just like a reservoir, its storage capacity remains constant, but its actual water volume is dynamic.

A battery with a marked capacity of mAh can emit different amounts of electricity under different discharge currents. The higher the current, the less energy can be released. This is caused by polarization inside the battery. Therefore, when discussing the battery life, you should also consider the discharge rate performance.

How to calculate the “4150mWh”?

The XTAR 4150mWh AA lithium battery adopts a cell of 3.6V 14430 1150mAh. The rating capacity comes from the capacity of the internal battery cell, because the cell capacity is fixed. It is 1150mAh*3.6V=4140mWh. The mAh capacity is 2500mAh, and it comes from XTAR lab’s test under the condition of a standard discharging current of 0.5A.

Convert the capacity mAh to mWh， it is 2500mAh x 1.5V=3750mWh, not the rated 4150mWh. What’s the reason:

The formula of “Voltage x mAh capacity=mWh energy” only works on 3.6/3.7V lithium-ion batteries. For the rechargeable 1.5V lithium-ion battery, there is a conversion loss due to the built-in voltage regulator circuit, typically estimated to be around 8% to 10%. Therefore, the discharging energy of the XTAR 4150mWh AA lithium battery is around 4150mWh*90%=3735mWh. That means, the energy after fully charging is 4150mWh, but it would be less in discharging due to the conversion loss.

Which devices do 1.5V lithium batteries work for and which devices do they not work for?

1.5V lithium batteries are generally suitable for most of the devices that use AA/AAA NiMH and dry batteries, especially those that require fast power consumption and stable power supply, such as wireless microphones, VR controllers, game controllers, RC toys, etc. They are also suitable for devices that are frequently used and require a large number of batteries, such as trail cameras, multimeters, sound mixers, Guitar amplifiers and so on. It is a wise investment for the medium/high-drain devices.

1.5V lithium batteries are not suitable for clocks. Most of the clocks are low-drain devices, while these batteries have a higher power output, resulting in faster battery consumption and need for frequent battery replacements. They are also not suitable for radios due to the noise caused by electromagnetic interference.

Can 1.5V lithium batteries work stably in extremely cold and hot weather?

The discharge operating temperature range for XTAR 1.5V lithium batteries is -20°C to 60°C. But extreme temperature would affect the battery performance.

Why does the 1.5V lithium battery not work on the high lumen flashlights?

The internal circuitry of 1.5V lithium batteries has limited current-handling capacity, making them unsuitable for high-current-demanding devices. Batteries with a stronger load-bearing capacity require better heat dissipation support.

NiMH and dry battery do not have protection designs and can reach a very high momentary current, so they can still work. While the 1.5V lithium battery has built-in protection board with over-current and temperature protection. The output will stop when the current exceeds 2-2.5A. Therefore, it is not recommended to use 1.5V lithium batteries in devices requiring instantaneous current exceeding 2.5A and continuous input current exceeding 2A. 

Some flashlights has no current limit design, and they use linear drives. This kind of flashlights only fit the unprotected rechargeable batteries and dry batteries. For the flashlight with 300lm or higher requires a discharging current of about 2.5A, the 1.5V lithium batteries are not suitable. For the regular EDC flashlights with small discharge current (less than 200LM), the 1.5V lithium battery can work well. 

In addition, if the 1.2V NiMH battery continuously discharge with current of more than 2A, it will shorten the cycle life. That’s why some new batteries have an obvious shorter battery life after a period of use.

Can it be used on camera flashes?

The 1.5V lithium battery does not work on some camera flashes. First, camera flashes require a high instantaneous current and consume a lot of power. The maximum protection current for 1.5V lithium battery is 2.5A, and if the power of flashes exceeds the battery’s maximum current limit, 1.5V lithium battery cannot be used. The second is that the battery will heat up and the temperature will rise after continuous flashing, causing the battery to enter protective status (but will not be damaged). Even you use NiMH batteries for camera flashes, you are suggested to use High-drain NiMH battery that can discharge at high rates.

How is the self-discharge rate?

Compared with NiMH battery, the self-discharge current of 1.5V lithium batteries will definitely be higher due to the built-in discharging and protection management circuit. However, the 1.5V lithium batteries make sure you will not over-discharge. And it has a almost 5.5x faster charging speed.

Can it be charged by regular 18650 battery chargers?

Can’t be charged. Because the rechargeable 1.5V lithium battery has a built-in charging/discharging management chip, and it needs the charging voltage of about 5V with constant charging. The regular 3.6V li-ion battery charger isn’t compatible with that special design. So, in order to using in safe, do not use the regular 18650 charger to charge the rechargeable 1.5V lithium battery.

It can be charged by XTAR VX4, MX4, L8, L4, BC8, BC4. It CAN’T BE CHARGED by XTAR FC2, VC4, VC4SL, VC2SL, VC8, VC8S, VC8 PLUS, VP4L PLUS, VP4 PLUS and other models.

How will the RC toys do if it is in low-power with 1.5V lithium battery?

In RC toys like LEGO, they usually use 6 AA or AAA batteries in series to get a discharging voltage of 9V. If one of the batteries is in low power, the total voltage will drop down, and the toys will gradually slow down in running.

Can NiMH AA replace the 1.5V lithium battery?

Some users believe that fully charged NiMH battery has a higher voltage and will stable to 1.5V when used on medium-drain devices. So they they it is not necessary to use 1.5V lithium battery. Actually, even the 1.2V NiMH battery can reach a maximum voltage of 1.45-1.6V after fully charged, its voltage will gradually drop during the discharge, and the voltage will quickly lower than 1.5V, so it cannot replace the 1.5V lithium battery.

Can it be used in the device immediately after fully charged?

As the AA lithium battery makes the voltage of its internal cell step down from the 3.6V to 1.5V, it need time to do it. So, if you install it into a low-voltage device immediately after fully charged, it may not work because it detects the battery voltage is still too high. XTAR lithium battery completes the voltage step-down in 5 seconds (and we tested the EBL battery is 12 seconds).

Why does the 1.5V lithium battery have a shorter run time in some devices?

Battery life is influenced by many factors, such as battery type, device power consumption, battery voltage and current requirements, self-discharge rate, battery lifespan, environmental conditions, etc. Without considering other factors, battery life (in hours) can be calculated as follows: battery capacity (mWh) / device power consumption (mWh). Typically, battery capacity (mWh) equals the battery’s capacity (mAh) multiplied by voltage (V). Even batteries with the same capacity, like 1.5V lithium batteries and NiMH batteries/alkaline batteries, have different discharge voltage curves. The 1.5V lithium battery maintains a constant 1.5V high voltage output, while the voltage of the 1.2V NiMH/alkaline battery gradually decreases during discharge.

If these batteries are used in low-drain devices, such as alarm clocks and TV remote controls, the devices have relatively broad voltage requirements, and they can work normally with low voltage. Using a constant 1.5V high voltage will quickly deplete the battery, while using NiMH batteries/alkaline batteries will result in slower power consumption.

If these batteries are used in medium to high-drain devices, such as VR game controllers, the devices are sensitive to voltage. When the battery voltage drops below 1.1V, the device may interpret it as insufficient battery power, leading to controller disconnection or unstable signal transmission. If a 1.5V lithium battery with constant voltage output is used, both overall performance and battery life will be better. However, when using 1.2V NiMH or alkaline batteries, the voltage drops rapidly, leading to a quick misjudgment of low battery capacity, resulting in shorter battery life compared to the 1.5V lithium battery.

Can the electromagnetic wave interference be solved?

Not yet resolved. Because the rechargeable 1.5V lithium battery has a built-in charging/discharging and voltage step-down circuit. It will cause electromagnetic effect from the inductance in the circuit. All the 1.5V lithium batteries on the market have such characteristic.  

If you’d like to learn more or have other questions about XTAR 4150mWh AA lithium batteries, please don’t hesitate to contact us.

When grading the XTAR 1.5V AA 4150mWh battery, why is the capacity value lower than claimed rating?

The labeling standard for the nominal energy of XTAR AA 4150mWh and AAA 1620mWh battery is: the energy comes from the cell energy before loss, and the capacity comes from the real measurement at 1.5V output. Due to the cell has 10% output loss, the battery capacity measured by VX4 charger is the output capacity after loss.

The advantage of using the 3.6V cell’s energy as the battery nominal energy is it helps avoid significant fluctuations in energy output due to conversion efficiency. First, the conversion efficiency of constant voltage step-down circuits will improve with industry advancements. Second, there are significant differences in conversion efficiency among different step-down circuits. For example, the conversion efficiencies of the constant voltage step-down circuit is 90%, while that of the linear step-down circuit is only 80%.

What is the discharge cutoff voltage of a 1.5V rechargeable lithium battery?

The 1.5V rechargeable lithium battery actually uses a 3.6V cell and achieves a 1.5V output through an internal step-down smart chip. As a result, the discharge cutoff voltage is determined by the internal step-down chip and cannot be directly measured by external devices.