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AA Li-Ion battery charged with USB-C

mipix  31 7299 Cool? (+11)
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TL;DR

  • 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.
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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
About Author
mipix
mipix wrote 4049 posts with rating 1457 , helped 489 times. Live in city Kluczbork. Been with us since 2003 year.

Comments

Marcin Sz. 16 Jan 2024 20:45

Is the output voltage cut off automatically after discharge, without warning or lowering the output voltage beforehand? [Read more]

mipix 16 Jan 2024 21:24

These types of AA sticks are advertised as follows: https://obrazki.elektroda.pl/4094904100_1705436406_thumb.jpg Which suggests keeping the voltage at 1.5V for cut-off. The 100% charge signal is... [Read more]

filimilite18 16 Jan 2024 23:50

Is the output voltage cut off automatically after discharge, without warning or lowering the output voltage beforehand? [Read more]

mipix 17 Jan 2024 07:47

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... [Read more]

LEDówki 17 Jan 2024 08:50

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.... [Read more]

zigipl 17 Jan 2024 09:39

There are cables available with several USB-C outputs https://www.amazon.com/GELRHONR-Splitter-Charging-Compatible-%EF%BC%884FT-1-25M%EF%BC%89/dp/B08GY7FBHZ so if anyone he often wanted to use it, there... [Read more]

mipix 17 Jan 2024 09:57

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... [Read more]

zigipl 17 Jan 2024 10:20

The cable must also support PD, so if they didn t be a problem. [Read more]

mipix 17 Jan 2024 10:43

Older protocols, e.g. Qualcomm Quick Charge 2.0, do not pay attention to the cable type. https://blog.oxplot.com/quickcharge/ https://en.wikipedia.org/wiki/Quick_Charge [Read more]

zigipl 17 Jan 2024 12:03

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. [Read more]

kuncy7 17 Jan 2024 17:37

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... [Read more]

Anonymous 18 Jan 2024 07:24

They are not suitable for such applications anyway. Current efficiency too low. Besides, does anyone else have such a battery-powered camera? After all, today`s smartphone will crush it with the quality... [Read more]

mipix 18 Jan 2024 08:23

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... [Read more]

LEDówki 18 Jan 2024 08:31

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... [Read more]

mipix 18 Jan 2024 09:12

When it comes to capacity, it`s not entirely true. Approximate capacity in size AA https://obrazki.elektroda.pl/6895243900_1705563733_thumb.jpg As for durability, time will tell. As you can see... [Read more]

LEDówki 18 Jan 2024 09:47

The average user doesn t think about it, and they won 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... [Read more]

zigipl 18 Jan 2024 13:26

I read opinions about these batteries and it looks very bad https://allegro.pl/oferta/akumulator-xtar-14500-1-5v-3300mwh-li-ion-4-szt-14508559254 https://allegro.pl/oferta/kp-icr14500-226pcm-2260mah... [Read more]

bsw 18 Jan 2024 20:32

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? [Read more]

zigipl 18 Jan 2024 20:43

What problem would such a battery solve? [Read more]

FAQ

TL;DR: 1.51 V ± 0.01 V regulated output until the Li-ion cell drops below 3.15 V [Elektroda, mipix, post #20913806] “Closer to a power bank than to an AA battery” [Elektroda, mipix, post #20913400] Capacity logged at 3.35 Wh per cell [Elektroda, mipix, post #20962456] Why it matters: Knowing cut-off, capacity and charging quirks prevents device damage and false runtime assumptions.

Quick Facts

• Nominal output: 1.51 V DC (ripple almost undetectable) [Elektroda, mipix, post #20912923] • Discharge profile: 1.51 V (4.2–3.15 V cell) → 1.10 V (3.14–2.80 V) → 0 V (≤2.80 V) [Elektroda, mipix, post #20913806] • Measured stored energy: 3.35 Wh (≈2.3 Ah @1.5 V) after USB-C charge [Elektroda, mipix, post #20962456] • Stated max discharge current: 3.5 A for LC9205D IC (datasheet) LC9205D datasheet • Typical retail price: PLN 13.50 per AA cell with USB-C port (2024 import) [Elektroda, mipix, post #20962456]

How does the USB-C AA battery shut down when empty?

The converter keeps 1.51 V output while the internal Li-ion cell stays between 4.20 V and 3.15 V. It then steps to 1.10 V until 2.80 V, after which it cuts output to 0 V without prior warning [Elektroda, mipix, post #20913806]

Can I recharge and power a device simultaneously?

No. When 5 V is applied on USB-C the battery presents 5 V at its terminals, so simultaneous charge-and-use would feed 5 V into a 1.5 V device and may destroy it [Elektroda, mipix, post #20913400]

What real capacity should I expect compared with alkaline AA?

One measured cell stored 3.35 Wh, equal to about 2.3 Ah at 1.5 V [Elektroda, mipix, post #20962456] Fresh alkaline AA averages 3.75 Wh (≈2.5 Ah) [IEC 60086]. Expect roughly 60–70 % of high-grade alkaline runtime.

Is there over-current protection?

The LC9205D IC claims 3.5 A peak discharge capability and includes short-circuit shutdown [LC9205D datasheet]. Forum tests up to 140 mA continuous showed stable voltage but motors were untested [Elektroda, mipix, post #20912923]

Are these cells eco-friendly?

Each cell contains a Li-ion pouch, boost/buck converter and charger, adding e-waste complexity versus simple NiMH. One post calls it “littering” because every battery carries extra electronics [Elektroda, LEDówki, post #20915557]

Do NiMH cells still beat Li-ion AA on cycle life?

Quality NiMH often handle 500–1000 full cycles, while typical pouch Li-ion manages 300–500 [IEC 61960]. Therefore NiMH may outlast USB-C AA in heavy-use scenarios.

How can I estimate capacity without a specialised tester?

  1. Attach a 10 Ω, 0.5 W resistor.
  2. Record start time; discharge until output falls to 1.10 V.
  3. Capacity (Ah) ≈ time (h) × 0.15 A. This ignores the last 10 % but yields useful approximation [Elektroda, Jacek Rutkowski, post #20962492]

What happens if I charge through a multi-port USB-C splitter?

Older fast-charge standards like Quick Charge 2.0 raise bus voltage on all branches, so parallel-charging several cells through a passive splitter can expose them to >9 V and damage electronics [Elektroda, mipix, post #20913962]

Edge case: will my multimeter buzz on a 9 V Li-ion substitute?

Yes. One user’s meter squealed due to converter noise in a 9 V lithium pack, despite normal behavior on alkaline or NiMH [Elektroda, mipix, post #20915496]

Can I get versions without USB-C?

Yes. Some Li-ion AA ship without a port and need a matched charger cradle [Elektroda, mipix, post #20915435] They free space for a larger cell but sacrifice universal charging.
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