I think I’ll just use this cell in low power applications. But I’m curious to know how that chip works… And why it is connected to capacitors.
I will look that up ’cuz I am curious also. I just have to eat first.
Willing to desolder the bad pcb in order to get a picture of the back? The protection IC isn’t on the top.
I did take a look at the underside of the PCB by slightly lifting it up. There is nothing on the other side appart from markings (“18650 2TC”).
Must be a protection ic with integrated mosfet.
Nice review! Thanks for sharing. I’m a big fan of Sanyo batteries.
Too bad Sanyo was bought by Panasonic 
It’s amazing the number of good company/people in Japan considering how small it is.
my guess is they are using the capacitors as a delay (for overcurrent or overcharge perhaps?)
Correct me if I’m wrong, but a quick change of voltage on the positive side (button top) will induce a current in these capacitors.
Maybe that this current is used to detect short circuits?
UPDATE:
As you can read in the first post, one of my cells arrived with a defective MOSFET, meaning that it has only half of the current capability.
After my tests, I placed the cell in storage (3.8V) and placed it aside. Today I wanted to use it for a flashlight that uses less than 2A, but when I took it out the voltage was down to 3.5V.
I charged it back up… and realized that it self discharged. So I popped the top plastic cover and guess what: The defective MOSFET was blown up and had slightly melted the black plastic cover. It was hot (about 50°C), so that’s what caused the high self discharge.
This is not very reassuring…
In the end I removed the defective chip from the PCB and now everything is fine. You just need to be very careful not to touch 2 legs at the same time when you remove the chip…