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Placeholder page with images of Chinese M18 Circuit Boards put up until I have time to properly upload/write...
Chinese M18 Battery Board 1 (Click to Expand)
Top
Bottom
Main IC - Eastsoft HR7P169BFGTF (I can't find a datasheet on this IC in english). I'm going to assume that is a convenient programming header just off to the left. This IC controls the UI LEDs and the communication with the charger and battery. It also handles the temperature sensor.
Cellwise 1051AL - This IC provides overcharge protection (threshold is 4.220VDC on this IC); It does not provide any sort of balancing. Datasheet (PDF, 495KB) has a handy diagram of how it should be wired (see below). Output of this chip (pin 8 - overcharge) gets fed through Diode (D6) and Resistor (R9) and connects to TP1 and Pin 4 of U1
RU3070 N-Channel MOSFET
I assume that U2 is a Positive Voltage Regulator, possibly 5VDC ('/50')
Markings on Board
GSB034
M18-18650
LTH20211028038R2
Top after unsoldering larger components
Bottom after unsoldering large components
Some Sanding to show traces (this is only a double sided board.
Chinese M18 Battery Board 2 (Click to Expand)
Battery Label
Battery with top cover removed
Circuit board top inside battery
CellWise CW1353 IC. This IC claims to have a lot of features - including Overcharge, Over-Discharge, Over-current, short circuit, Temperature Protections. It supposedly also supports cell balancing. I don't see any support for communication to another microcontroller, so it isn't exactly clear how it can perform all those functions if it can't actually cut off power draw from the battery pack. (there is only a over-charge protection output.) There are quite a large amount of transistors and extra resistors around this IC. I can't read chinese, but there is a diagram in the datasheet which appears pretty close to what I am seeing on this board (image below). It would appear that cell balancing requires external transistors on this IC (and cell balancing is possible on this board!)
Cmsemicon CMS8S6990N Microcontroller. Hmm.. an 8051 MCS-51 compatible microcontroller with 16KB Program Flash & 256KB RAM. Yes, here is a Datasheet (PDF, 926KB) You can also see the circuit board markings - 'RH-M18B-V1.0 2022/03/29' as well as what appears to be a programming header to the left of this IC.
PT4407 P-Channel MOSFET - We're going to assume this is the charging cut-off transistor until I get a chance to dig into this deeper.
Chinese M18 Battery Board 3 (Click to Expand)
Circuit Board Top
Circuit Board Bottom
Unlabeled Main IC... This doesn't look promising. I'd probably avoid this board if I saw it for sale anywhere.
D425 Transistor/MOSFET? I can't find any info on this transistor... Going to need some help here.
There is also a 6203A voltage regulator on this board as well, but this one seems to be 3.0VDC output. Other than that, we have a temperature sensor and not much else. Not even a programming header!