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AA Li-Ion battery charged with USB-C

mipix 7911 31

TL;DR LABEL_AI_GENERATED

  • Teardown of a USB-C rechargeable AA lithium-ion battery reveals a hidden LC9205D converter inside.
  • The LC9205D handles charging, discharging, and protection for a 3.7V-to-1.5V lithium dry battery with only two capacitors, one resistor, and one inductor.
  • The label states 140mA, and the measured output is 1.51V with almost imperceptible ripple.
  • Charging failed on the sample, spilling electrolyte and corroding the connections, but the electronics still seem functional for clocks, remotes, and watches.
AI summary based on the discussion. May contain errors.
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  • Packaging of four AA Li-ion USB-C 1.5 V batteries with a charger.

    Hello

    Below are photos of the inside of an AA battery with a lithium-ion cell. The link itself has no visible marking. There was a problem with charging from new, so the whole thing was dismantled. As you can see, the electrolyte was spilled and the connections were corroded. The electronics themselves seem to be functional and may be used in a wall clock with an 18650 cell.
    Inside there is an LC9205D converter. According to the description on the label, the current capacity is 140mA.
    Close-up of a battery interior with visible electronic components and corrosion. Interior of an AA battery with damaged electronics and corrosion. Image of the interior of an AA battery with a visible lithium-ion cell and LC9205D converter. Close-up view of the corroded interior of an AA battery with a lithium-ion cell. Close-up of the interior of an AA battery showing electronics and a converter. Close-up of corroded connection in AA lithium-ion battery. Interior of corroded AA battery with leaking electrolyte. Disassembled AA battery with visible damage and corrosion. View of the inside of an AA battery with a damaged lithium-ion cell. Three green AA lithium-ion batteries with multilingual labels, lying on a light background. Three green AA Li-ion USB-C batteries with red ends. Three AA batteries side by side with visible positive terminals. Three AA rechargeable batteries with USB-C port. Packaging of AA lithium-ion battery with labels and instructions. Description from the Chinese website:
    Quote:
    LC9205D is a three-in-one integrated chip used in 3.7V to 1.5V lithium dry battery. Mainly intended to replace traditional AA alkaline batteries and 1.2V AA nickel-metal hydride batteries.

    The LC9205D chip achieves a high degree of integration. One chip completes the charging, discharging and protection functions of a lithium battery.

    The peripheral circuit requires only two capacitors, one resistor and one inductor.

    1. Highly integrated, three in one;
    2. High reliability, under voltage, overcharge, short circuit, overheating and lithium battery protection;
    3. Very low self-discharge, less than 6uA;
    4. With NTC temperature control to better protect the battery;
    5. Supports maximum discharge of 3.5A to meet high power discharge requirements;
    6. Streamline peripherals Total production cost is reduced by up to 50%


    Chinese specification for LC9205D converter. Circuit diagram with LC9205D converter Wiring diagram and layout of LC9205D converter.


    The measured output voltage is 1.51V with almost imperceptible ripple.
    Screenshot of an oscilloscope graph showing a voltage waveform. Close-up of a damaged AA battery interior with a USB display showing 1.3 W.

    The other three work. Due to the low output current, they can be used in remote controls and watches. Electric toys with motors have not been tested, so it is not known whether the system has any overcurrent protection.

    There are also AAA versions with an output current of 100mA
    Four AA lithium-ion rechargeable batteries labeled Activ Energy.

    Regards

    Cool? Ranking DIY
    About Author
    mipix
    Level 38  
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    mipix wrote 4069 posts with rating 1483, helped 495 times. Live in city Kluczbork. Been with us since 2003 year.
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  • #2 20913300
    Marcin Sz.
    Level 25  
    Posts: 794
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    Is the output voltage cut off automatically after discharge, without warning or lowering the output voltage beforehand?
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  • Measured cutoff and failure behavior of USB-C AA cells

    #3 20913400
    mipix
    Level 38  
    Posts: 4069
    Help: 495
    Rate: 1483
    These types of AA sticks are advertised as follows:
    AA Li-Ion battery charged with USB-C
    Which suggests keeping the voltage at 1.5V for cut-off.
    The 100% charge signal is only visible when 5V is connected via USB, then the indicator light is on continuously.
    Charging is indicated by slow flashing.
    In my case, the light flashed very quickly - this condition is not described on the packaging, but it signals a cell failure - open circuit.

    Measurements have shown that below the voltage of 3.15V on the cell, the output voltage is suddenly reduced to 1.1V. The power supply is cut off at 2.8V on the cell.
    Output voltage of two AA batteries displayed on a screen.

    When charging at the output instead 1.5V Is 5V , which makes it impossible to charge and use the "battery" at the same time.
    When you think about it, from the electronic point of view, it is closer to a power bank than to an AA battery, with the difference that it does not increase the voltage from 3.6V to 5V, but lowers it to 1.5V.
  • #4 20913638
    filimilite18
    Level 2  
    Posts: 9
    Rate: 1
    Is the output voltage cut off automatically after discharge, without warning or lowering the output voltage beforehand?
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  • #5 20913806
    mipix
    Level 38  
    Posts: 4069
    Help: 495
    Rate: 1483
    I`ve written this before, but I`ll say it again:
    In the cell voltage range of 4.20 V ... 3.15 V, the converter output is 1.51 V
    In the cell voltage range of 3.14 V ... 2.80 V, the converter output is 1.10 V
    Below the voltage of 2.80 V on the cell, the converter output is 0 V

  • USB-C cell is effectively a single-cell power bank

    #6 20913880
    LEDówki
    Level 43  
    Posts: 9630
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    The battery with the converter and charger is a power bank. :D
    The cell mentioned in the description is a secondary electrochemical cell - a battery. :D
    Nice for powering something from one battery. Once discharged, it can be removed and charged. 5V into a device designed to be powered by 1.5V may end badly for the device with this powerbank.
    Using 4 pieces in a camera or blood pressure monitor is a pain, because you have to connect them to the power supply one by one, or have several power supplies, or have a power supply with several USB ports and several cables. If someone likes it, why not? In terms of volume, the solution is quite similar to a charger with 4 sockets and a mains adapter. And you can borrow a power supply from someone, because now everyone has one, and often more than one.
  • #8 20913962
    mipix
    Level 38  
    Posts: 4069
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    Rate: 1483
    The set includes a cable with a branch for 2 pcs.

    These branched cables are dangerous in certain cases. When connecting one output to a device with the fast charging protocol, a voltage higher than 5 V will appear on all terminals. Not every device with a USB connector will withstand higher voltage. You need to be careful.

    https://www.usb.org/usb-charger-pd
  • #9 20913993
    zigipl
    Level 15  
    Posts: 130
    Help: 2
    Rate: 32
    The cable must also support PD, so if they didn`t mix it up, there shouldn`t be a problem.
  • #11 20914201
    zigipl
    Level 15  
    Posts: 130
    Help: 2
    Rate: 32
    Thanks, they actually figured it out cleverly. Maybe someone with an electrode will be tempted to open such a splitter. Maybe there`s some security inside.

  • Measured converter output drops below 3.14 V cell voltage

    #12 20914718
    kuncy7
    Level 9  
    Posts: 34
    Help: 1
    Rate: 6
    mipix wrote:
    I`ve written this before, but I`ll say it again:
    In the cell voltage range of 4.20 V ... 3.15 V, the converter output is 1.51 V
    In the cell voltage range of 3.14 V ... 2.80 V, the converter output is 1.10 V
    Below the voltage of 2.80 V on the cell, the converter output is 0 V

    Thanks!
    I have something like this, only in the R20 version in a gas heater, just yesterday
    the diode in the stove started flashing, indicating that the power supply voltage was too low.
    This surprised me because I thought it would work until it completely failed.
    This is how a toothbrush works, it turns off without warning.
  • #13 20915404
    Anonymous
    Level 1  
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  • Aliexpress AA Li-ion cells with 600 mAh capacity

    #14 20915435
    mipix
    Level 38  
    Posts: 4069
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    Rate: 1483
    They are not universal, but they are certainly perfect for what kucy7 writes. If there was no demand, there would be no supply.

    Out of curiosity, I searched a bit on Aliexpress and there are those with a capacity of 600 mA (max 2000 mA).
    AA Li-Ion battery charged with USB-C

    There are also versions without a charging port. These must have a special charger.
    AA Li-Ion battery charged with USB-C DLG battery set with charger, featuring AA and AAA batteries and information on charge cycles and charge time.

  • Critique of USB-C AA cells as lower-capacity substitutes

    #15 20915445
    LEDówki
    Level 43  
    Posts: 9630
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    Demand/supply - this is simple manipulation. The manufacturer forces people to buy a product with a lower capacity than alkaline cells or NiMH batteries. It also has a shorter lifespan than NiMH, so only fashion should make a person buy it. And if fashion controls someone`s life, let them spend money on low-quality, but fashionable goods. In my opinion, the Chinese are trying to take over the alkaline cell market and perhaps they will succeed with the help of housewives and the EU, which forced the standardization of power sockets. Now everyone has the so-called charger, so there is nothing stopping you from using these substitutes for alkaline cells or NiMH batteries.

  • Cheap AA USB-C cells have only about 700 mAh

    #16 20915496
    mipix
    Level 38  
    Posts: 4069
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    When it comes to capacity, it`s not entirely true. Approximate capacity in size AA
    Table showing the approximate capacities of different types of AA batteries.

    As for durability, time will tell. As you can see in the first message, it is different, because the cell with a production date of December 2023 (a month old) had a defect. Nevertheless, I ordered 2 pieces of the cheapest ones for testing in the wall clock. According to the buyers` description, they have about 700 mAh instead of 2600 mAh, but otherwise it was impossible to buy converters from 3.7V to 1.5V. Currently this is the only source. Ultimately, they will be connected to 18650 cells.
    Two AA Dadoli USB rechargeable batteries with 2600 mAh capacity.

    I also use a 9V substitute in a multimeter. An interesting fact is that on a regular battery or NiMH accumulator, the meter works normally, but on the Chinese invention it makes a squeaking sound. It`s the fault of the converter in the battery. Declared capacity taken from the ceiling.
    AA Li-Ion battery charged with USB-C

    There are also those that promise not to "noise", but I`m not going to test it.
    Two black 9V USB batteries labeled FOR MUSIC with a connection diagram.

  • Market-driven critique of USB-C rechargeable AA cells

    #17 20915557
    LEDówki
    Level 43  
    Posts: 9630
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    The average user doesn`t want to bother with charging. The charger is a big expense and you have to think about it. These products are targeted at such users - they already have chargers, they won`t think about it, and they won`t be able to count any profits or losses. Why does your neighbor buy such expensive sticks when you can buy cheap ones? And he doesn`t know that cheap ones last half as long. It wastes time shopping and exchanging and produces a mountain of waste.
    This is also an example of littering - in every "power bank", a substitute for a dry cell, there is a converter and a charger, i.e. additional electronic waste. Lithium-ion batteries have a service life (number of complete discharge/charge cycles) lower than NiMH. The only advantage is higher energy density, but it is invisible here, because there are converters and chargers instead of a battery, possibly at the expense of the battery capacity.
    A plus for signaling the low state with low voltage, thanks to which the powered device shows that it is time to charge.
    I still think it`s more of an attempt to take over part of the market than any benefit to the consumer. The role of the consumer is to consume and let him decide what he wants to consume and for how much.
  • #19 20916665
    bsw
    Level 22  
    Posts: 701
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    Usually, such batteries in remote controls come in pairs. Why didn`t anyone come up with the idea of having only one 3V battery + a jumper battery?
    Helpful post? Buy me a coffee.
  • #20 20916684
    zigipl
    Level 15  
    Posts: 130
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    What problem would such a battery solve?
  • #21 20917162
    bsw
    Level 22  
    Posts: 701
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    Rate: 732
    1. Converter from 3.7 to 3, not 1.5V
    2. Only one battery to charge
    3. Charging without removing the battery from the remote control (only the cover removed)
    Helpful post? Buy me a coffee.
  • #22 20918347
    zbyszekkr
    Level 17  
    Posts: 231
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    LEDówki wrote:
    (...) Lithium-ion batteries have a service life (number of full discharge/charge cycles) lower than NiMH. The only advantage is higher energy density, but it is invisible here, because there are converters and chargers instead of a battery, possibly at the expense of the battery capacity.
    (...)
    In my opinion, the biggest advantage is the lack of memory and the ability to recharge at any time.

  • Single-cell Li-ion remote control conversion with diode and sensor

    #23 20918357
    Jacek Rutkowski
    Level 28  
    Posts: 1330
    Help: 69
    Rate: 275
    bsw wrote:
    1. Converter from 3.7 to 3, not 1.5V
    2. Only one battery to charge
    3. Charging without removing the battery from the remote control (only the cover removed)

    I took the easy way and used one cell with a !N4148 diode in series with the ZY_TH1 temperature sensor Tuya WiFi every 2 AAA batteries milked in about 3 weeks.
    Now I have a 3.7V 3500mAh cell and it has been working for 8 months.

    I power the Sony UCT-042 TV remote control directly from a 600mAh cell, probably from a Nokia 3310. There, it charges the cell to 3.6V and lasts about 4 months without charging. :)
  • #24 20918629
    Anonymous
    Level 1  

  • Critique of USB-C AA battery practicality and use cases

    #25 20927218
    Jawi_P
    Level 36  
    Posts: 3259
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    Rate: 715
    LEDówki wrote:
    perhaps he will succeed with the help of housewives and the European Union, which forced the standardization of power sockets. Now everyone has the so-called charger, so there is nothing stopping you from using these substitutes for alkaline cells or NiMH batteries.

    After all, these cells have been on Ali for years! What Union and conspiracy again?
    The second thing is that the solution is very good, even for devices that can only handle 1.2V batteries on average. E.g. old mice. I have one myself and the battery is OK, but the battery life is very short, the voltage drops to the nominal value and that`s it. Such a combined cell would work well in such solutions, in all those that are power-hungry and this cell will cope and require quite high voltage for a finger.

    Added after 4 [minutes]:

    bsw wrote:
    Usually, such batteries in remote controls come in pairs. Why didn`t anyone come up with the idea of having only one 3V battery + a jumper battery?

    Oh my, what a saving. My TV remote has been working on batteries for... 6 years? At least, what`s the point of using batteries, let alone such inventions?

    Added after 7 [minutes]:

    Jacek Rutkowski wrote:
    I power the Sony UCT-042 TV remote control directly from a 600mAh cell, probably from a Nokia 3310. There, it charges the cell to 3.6V and lasts about 4 months without charging.

    What is this modification for? Because for this purpose, I wouldn`t want to remove the flap from the remote control :) Not to mention soldering something etc. And if you put in regular alkaline batteries, after a few years you might forget what type of cells are there :)
    So, every 4 months you load your invention. And now think about it, you`re not at home, you were run over by a bus, you were eaten by a wild boar in the forest... and your family threw away the remote control because there are some strange batteries in there.
    Standard solutions have a lower price and are usually less annoying :)

  • Frequent remote use justifies rechargeable cell mod

    #26 20945503
    Jacek Rutkowski
    Level 28  
    Posts: 1330
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    Rate: 275
    Jawi_P wrote:
    Jacek Rutkowski wrote:
    I power the Sony UCT-042 TV remote control directly from a 600mAh cell, probably from a Nokia 3310. There, it charges the cell to 3.6V and lasts about 4 months without charging.

    What is this modification for? Because for this purpose, I wouldn`t want to remove the cover from the remote control, not to mention soldering something etc. And if you put in regular alkaline batteries, after a few years you might forget what type of cells are there
    So, every 4 months you load your invention. And now think about it, you`re not at home, you were run over by a bus, you were eaten by a wild boar in the forest... and your family threw away the remote control because there are some strange batteries in it.
    Standard solutions have a lower price and are usually less annoying

    Apparently you don`t use the remote control much - or my remote control is terribly power-hungry :)

    Seriously, I currently have a 4-year-old at home who, when he comes back from kindergarten, likes playing with small cars and often uses remote controls as bridges. He probably presses it every time and transmits for several hours at a time. Previously, I had to replace the AAA batteries every few weeks, and now when it doesn`t work, I use the power supply set to 3.6V 500mA and after about 1-1.5 hours I have a charged battery. During this time, my son operates the buttons because they are on the side of the screen and he can reach them :)
    Earlier, the daughter from 2012 was bothering the remote controls...

    Besides, my TV remote controls last less than 3 years and that`s because they broke and now it`s the 4th or 5th remote control because the TV is from 2011 and SONY KDL 40CX420 and I`m waiting for the fluorescent lamps/LEDs to die.

    Theoretically, the symbol means a TV with CFL, and when I bought it it was described as LED. It consumes about 45W during operation and unmeasurable power in standby, so I`m calmly waiting for it to die to check what`s inside.

    I happened upon a long-lived one :)

  • USB-C cell capacity estimated at 2233 mAh equivalent

    #27 20962456
    mipix
    Level 38  
    Posts: 4069
    Help: 495
    Rate: 1483
    I have a new cell straight from Ali. A customs fee has been added to the shipment, to be paid upon receipt at the post office. As a result, the package stayed there for about a week. Delivery time equal to one month. Final price 1 pc. it`s PLN 13.50.
    Two AA batteries in a hand, one with visible markings Dadolii and specification 1.5V 2600mAh. USB tester displaying charging parameters and a 1.5V 2600mAh AA battery.

    The manufacturer did not provide the output current.
    I discharged it with a flashlight to cut off the power to the cell electronics.
    Charging via USB with 5V is 670mAh. (670mAh × 5V)/1000 = 3.35Wh. Here it is about 2233mAh after conversion to 1.5V.

    An AA alkaline cell is approximately 3.75Wh, which corresponds to 2500mAh.

    I`m not sure if I calculated the capacity correctly.

  • Questioning the 1.5 V output current calculation

    #28 20962482
    Jacek Rutkowski
    Level 28  
    Posts: 1330
    Help: 69
    Rate: 275
    mipix wrote:
    USB tester displaying charging parameters and a 1.5V 2600mAh AA battery. [img-1]


    Is this result for charging from 5V?
    5V*0.67Ah=3.35Wh

    3.35Wh/1.5V=2.3Ah
    If so, it is quite possible to recover approximately 1800-2000mA at 1.5V, because the converter reduces the voltage impulsively when charging, but does not emit heat, and then reduces it again in impulses from 3-4V, so it had to be checked at 1.5V how much current it will give...

    Do you see what the catch is?
  • #29 20962485
    mipix
    Level 38  
    Posts: 4069
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    Rate: 1483
    Yes. Unfortunately, my charger with a discharge and measurement function does not respond to this invention.

  • 10 Ω load gives 150 mA discharge test

    #30 20962492
    Jacek Rutkowski
    Level 28  
    Posts: 1330
    Help: 69
    Rate: 275
    mipix wrote:
    Yes. Unfortunately, my charger with a discharge and measurement function does not respond to this invention.


    This converter gives a stable 1.5V until the very end. Connect a 10R 0.5W resistor and you will have 150mA power consumption.
    after 10 hours, measure the voltage, it will be 1500mAh and after 14 hours 1900mAh.

    Unless you have a watch with a 1.5V battery, connect it :)
    you will see when it stops and its power consumption is negligible compared to 150mA :)
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Topic summary

LABEL_AI_GENERATED
The discussion revolves around the performance and characteristics of AA lithium-ion batteries designed for USB-C charging. Users report issues with voltage cut-off during discharge, with specific voltage thresholds noted: 1.51V output from 4.20V to 3.15V, dropping to 1.10V between 3.14V and 2.80V, and 0V below 2.80V. Concerns are raised about the batteries functioning more like power banks than traditional AA batteries, particularly regarding their inability to provide 1.5V while charging at 5V. The conversation also touches on the practicality of using these batteries in devices, the potential dangers of using branched USB-C cables, and the overall market dynamics of lithium-ion versus alkaline batteries. Users express skepticism about the longevity and efficiency of these lithium-ion batteries compared to traditional options, citing issues with capacity and the environmental impact of electronic waste.
AI summary based on the discussion. May contain errors.
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FAQ LABEL_AI_GENERATED

TL;DR: At 1.51 V output and about 140 mA current, these USB-C AA Li-ion cells act like tiny regulated power banks: “closer to a power bank than to an AA battery.” This FAQ helps buyers and tinkerers understand charging behavior, cutoff, real capacity, and safe device fit before replacing alkaline or NiMH cells. [#20913400]

Why it matters: A regulated 1.5 V Li-ion AA can solve low-voltage device issues, but its abrupt cutoff, limited output current, and USB charging quirks can also cause unexpected failures.

Option Nominal output in use Behavior near empty Best fit from the thread
USB-C Li-ion AA 1.51 V regulated Drops to 1.10 V, then 0 V clocks, remotes, some mice, gas heaters
NiMH AA about 1.2 V gradual decline general rechargeable use
Alkaline AA about 1.5 V gradual decline simple low-drain devices
High-drain toys/motors needs more current may overload low-current USB-C AA not confirmed suitable

Key insight: The main advantage is not raw capacity. It is stable 1.5 V output from a 3.7 V Li-ion cell, until the control chip forces a sharp low-battery transition and shutdown.

Quick Facts

  • The teardown found an LC9205D chip and a label stating 140 mA current capacity for the AA version; the measured output was 1.51 V with almost imperceptible ripple. [#20912923]
  • Measured discharge behavior was specific: 4.20 V to 3.15 V on the internal cell gives 1.51 V out, 3.14 V to 2.80 V gives 1.10 V out, and below 2.80 V the output becomes 0 V. [#20913806]
  • Charging status used three visible states in the thread: slow flashing = charging, solid LED = full with 5 V connected, and very fast flashing = cell fault/open circuit. [#20913400]
  • One later AliExpress sample cost PLN 13.50, took about one month to arrive, and accepted 670 mAh at 5 V, equal to 3.35 Wh input energy. [#20962456]

How does an AA Li-ion battery with USB-C charging keep a steady 1.5 V output, and what role does the LC9205D chip play inside it?

It uses a regulated converter, not the raw Li-ion cell voltage, to hold the output near 1.5 V. The teardown identified an LC9205D and measured 1.51 V at the terminals. "LC9205D is an integrated power-management chip that charges, discharges, and protects a 3.7 V Li-ion cell while feeding a regulated 1.5 V AA-style output." In the thread’s quoted description, one chip handles charging, discharging, and protection with only a few external parts. [#20912923]

What happens to the output voltage of a 1.5 V USB-C rechargeable AA cell as the internal Li-ion cell drops from 4.2 V to 2.8 V?

It stays near 1.51 V for most of the discharge, then drops sharply before cutoff. The measured ranges were 1.51 V output from 4.20 V down to 3.15 V on the internal cell, then 1.10 V from 3.14 V to 2.80 V, and finally 0 V below 2.80 V. That means the user sees a regulated plateau, a brief low-voltage stage, and then a shutdown. [#20913806]

Why does a USB-C rechargeable AA battery suddenly fall to about 1.1 V before shutting off instead of gradually weakening like an alkaline cell?

It falls suddenly because the converter regulates the output until the Li-ion cell reaches its protection threshold. An alkaline cell naturally sags over time, but this design holds 1.51 V until the internal cell reaches about 3.15 V, then the converter drops to 1.10 V and shuts off at 2.80 V. As the teardown author put it, it is “closer to a power bank than to an AA battery.” [#20913400]

How can I tell from the LED indicator whether a USB-C AA battery is charging normally, fully charged, or has a cell fault such as an open circuit?

You can read the LED by its blink pattern. Slow flashing means normal charging. A steady light means 100% charge, but only while 5 V is still connected through USB. Very fast flashing was observed on a failed unit and was interpreted as a cell fault caused by an open circuit. The packaging shown in the thread did not describe that fast-flash state. [#20913400]

What is LC9205D, and how is it different from a simple buck converter used with a separate charger and protection circuit?

LC9205D is a three-in-one battery-management and conversion chip, not just a simple step-down regulator. The thread’s quoted description says it combines charging, discharging, and protection for a 3.7 V to 1.5 V lithium “dry battery” in one IC. A plain buck converter would only reduce voltage. This chip also adds under-voltage, overcharge, short-circuit, overheating, and lithium-cell protection in the same device. [#20912923]

What is USB Power Delivery (USB PD), and why can branched USB-C charging cables be risky with rechargeable AA batteries or other 5 V devices?

USB PD is a USB charging standard that can negotiate voltages above 5 V, so a branched cable can create an overvoltage hazard if one branch triggers a higher profile. The thread warns that when one output connects to a fast-charging device, a voltage higher than 5 V may appear on all terminals. That can damage simple 5 V devices or rechargeable AA cells that expect only basic USB input. "USB Power Delivery is a charging protocol that negotiates voltage and current over USB-C, with higher-than-5 V operation as a key feature." [#20913962]

How does Qualcomm Quick Charge 2.0 differ from USB PD in the context of split charging cables and overvoltage risk?

Quick Charge 2.0 was described as less cable-aware, which increases concern with split cables. In the thread, one poster noted that older protocols such as Qualcomm Quick Charge 2.0 do not pay attention to cable type, unlike USB PD where negotiation and cable support matter more. The practical risk is the same: a branch intended for 5 V-only devices can see a higher voltage than expected. [#20914031]

Which devices are these 1.5 V Li-ion AA batteries actually suitable for, such as wall clocks, remotes, mice, and gas heaters, and which loads are too demanding?

They suit low-drain devices that benefit from a stable 1.5 V output. The thread explicitly mentions wall clocks, remote controls, and watches as good fits, and later users described successful use cases in an old mouse and a gas heater. Motorized toys were not tested, and the original teardown warned that overcurrent behavior was unknown. With a stated AA current capacity of 140 mA, demanding loads are the risky category. [#20912923]

AA Li-ion 1.5 V rechargeable batteries vs NiMH AA cells vs alkaline AA batteries — which is better for remote controls, clocks, and motorized toys?

For remotes and clocks, the 1.5 V Li-ion type is best when stable voltage matters more than simplicity. NiMH and alkaline cells decline more gradually, while the regulated Li-ion cell keeps 1.51 V for most of its run. The tradeoff is lower current on some versions, extra electronics, and abrupt cutoff. For motorized toys, the thread gives no positive test result, so alkaline or stronger rechargeables remain the safer choice. [#20912923]

How can I estimate the real capacity of a USB-C rechargeable 1.5 V AA battery from a measured 5 V charging input in mAh or Wh?

Convert the measured 5 V charge input to watt-hours first, then divide by 1.5 V for an optimistic equivalent mAh figure. In the thread, 670 mAh charged at 5 V gives 3.35 Wh. Dividing 3.35 Wh by 1.5 V yields about 2.23 Ah, or roughly 2233 mAh equivalent at 1.5 V before converter losses. That number is an estimate, not a true delivered capacity under load. [#20962456]

What is the right way to test the discharge capacity of a regulated 1.5 V Li-ion AA battery when a normal charger/tester does not recognize it?

Use an external load and time the discharge at the regulated output, not a standard charger/tester. 1. Connect a known resistor or device to the 1.5 V output. 2. Measure current and log runtime until shutdown. 3. Calculate delivered mAh or Wh from current, voltage, and time. One user suggested a 10 Ω, 0.5 W resistor for about 150 mA load, but the thread also warns that accurate measurement needs more than “a resistor and a clock.” [#20962845]

Why might a 9 V Li-ion replacement battery make a multimeter squeak, and what does that say about converter noise in these batteries?

The squeak points to switching-converter noise inside the regulated battery. One user reported that a multimeter worked normally on a regular 9 V battery or NiMH pack, but squeaked on a Chinese 9 V Li-ion replacement. He blamed the converter in the battery. That suggests some regulated replacement batteries inject audible or electrical noise, which can matter in sensitive instruments even when the nominal voltage is correct. [#20915496]

What practical problems come up when charging four USB-C AA batteries for a camera or blood pressure monitor, and what charging setups help?

The main problem is logistics, not chemistry. Four cells usually need four USB connections, so charging can become awkward unless you have several ports or a splitter cable. The thread notes that some sets include a 2-way branch cable, and multi-output USB-C splitter cables also exist. The risk is that a bad split setup can expose every branch to more than 5 V if fast charging activates, so simple parallel charging is not always safe. [#20913939]

How would a single 3 V regulated battery plus a dummy spacer compare with using two separate 1.5 V rechargeable AA cells in a remote control?

A single 3 V regulated battery plus a dummy spacer would simplify charging because you would charge only one cell. The proposal in the thread lists three benefits: conversion from 3.7 V to 3.0 V instead of 1.5 V, only one battery to charge, and possible charging with the cover removed instead of removing two cells. The drawback is that this was only a concept in the discussion, not a tested product. [#20917162]

Why do some AliExpress and Allegro listings for 1.5 V Li-ion AA cells claim very high capacities like 2600 mAh or 3300 mWh, and how should those numbers be interpreted?

Those numbers often mix different voltage bases, so they are easy to misread. A listing may quote mWh for the internal Li-ion energy or a 1.5 V-equivalent mAh figure after conversion. In the thread, buyers reported some cheap cells had about 700 mAh instead of the advertised 2600 mAh, and one 3300 mWh class listing drew skepticism. Treat such claims as marketing until you verify delivered energy at the actual 1.5 V output. [#20915496]
AI summary based on the discussion. May contain errors.
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