Product specifications (on the case):
Capacity: 12000mAh
Lifecycle: above 1000 times
Output: 12V
USB Port: 5V 2.1A/1A
Input: CC/CV 15V/1A
Starting Current: >200A
Peak current: 400A(<3s)
LED life: 100,000H
LED: 1W
LED lumen: 86LM
Operating Temperature: -20C - 60C
Fully charge time: about 3 hours
Size: 185x83x43mm
Measured total weight: 384g, battery pack weight: 266g. Compared with a 22.2V 1300mAh, (65A (50C) continuous, 104A burst discharge) battery pack weighs 207g, 12000mAh claim seems highly exaggerated; in the same density, it would be about 3300mAh. A range of 638g to over 820g for 12000mAh 3S battery pack is reported by an internet search. The most generous explanation is 12000mAh is total of 3 cells, which would imply 4000mAh in the ballpark of something reasonable. If it does indeed produce 200A, it would be 4000mAh at the 50C discharge rate.
After some years, but not too many uses,
it started bulging in the middle and the casing cracked. Not
surprisingly it is caused by the swollen LiPo battery pack.
Removing 4 screws with a size 1 Philips screwdriver to open the casing. The battery pack is secured to the case with an adhesive strip.
The charging controller is MP26123 (QFN16), a switching battery charger, which supports 2 or 3-cell battery pack with charging current up to 2A. One thing to notice is that the electronics does not have access to the
cell voltages, which implies that cell balancing is not done by the the main PCB. Perhaps there is something inside the battery pack.
There are two other switching regulators, as evident in the two inductors, 6.8uF and 330uF, for the USB 5V and the other constant current drive for the 1W LED respectively. One of the USB connectors has resistors on the signals to indicate higher current. One component is identifiable, EMB20P03G, which is a P-channel MOSFET, 30V, 10A, 20mOhms in the SO-8 package. U7 is suspected to be a microcontroller, which would decode the push button, and control the 4 LED indicators and the LED light pattern.
We are going to something dangerous: deflate the battery pack. There are a plenty of warnings on the internet of not puncturing the battery pack; but they are really about shorting the cell layers. If we are careful only to pierce the package not cells, we can release the gas not damaging the cells. Inside the pouch is a stack of thin layers, copper foil coated with graphite (anode), electrolyte (lithium salt in organic solvent) in the gel form saturating the separator, aluminum foil coated with lithium compound (such as lithium cobalt oxide, cathode). Puncturing the separator shorts the anode and the cathode which generates heat and can ignite the flammable electrolyte. It is also warned that the gases are toxic; it appears that the main gas is CO2, O2, but there are also CO and others, so well ventilated area is required. First we discharge the battery as much as possible by turning on the LED light; the LED shuts off at around 9.8V. The voltage will drift back up a little.
Removing the wrapper reveals the three swollen battery pouches.
We poke a small hole almost horizontally to the pouch, but not touching the lithium ion cell stack and after squeezing out the gases, we seal the hole quickly with Kapton tape. Then we wrap them back together. The seal is probably not perfect; that could affect the battery cells, such as drying up the electrolyte, but we don't expect it to work for too long or use it for high discharging. I did smell some odor when the gases were released.
We now charge the battery pack with 15V/1A. We should expect about 2-3 hours of charging time if there is still significant capacity left. It took 4 hours for the LED indicator to stop blink. The end voltage is 12.54V; the charging effectively stopped after 3 hours and probably transitioned from constant current to constant voltage after 2 hours. We'll run a discharge time to confirm the capacity using the USB current meter; we use a LED light that draws 0.5A from 5V. When fully discharged (at shutoff), the voltage is 9.9V V and the measured capacitor is 15800mWh. Assuming 15% loss, that puts the capacity at 1670mAh, perhaps 40 to 50% of the original capacity.
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