I know that in some cases where the laptop does not boot it is possible to bypass the first mosfet to make it boot again but how safe is it and what's the worst that can happen?
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OpenBoardView — https://github.com/OpenBoardView/OpenBoardView -
Re: Bypass mosfet safety
This is from the TI BQ24780S datasheet. You can learn a lot by reading these.
"The ACDRV drives a pair of common-source (CMSRC) N-channel power MOSFETs (ACFET and RBFET) between adapter and ACP. The ACFET separates adapter from system and battery, and provides a limited di/dt when plugging in adapter by controlling the ACFET turn-on time. Meanwhile, it protects the adapter when the system or battery is shorted. The RBFET provides negative input voltage protection and battery discharge protection when adapter is shorted to ground, and minimizes system power dissipation with its low RDS(on) compared to a Schottky diode."
Shorting out the first MOSFET is a hack used by some when troubleshooting, but it's not something that should be left that way. Most controllers will disable charging the battery if this FET is bypassed. Additionally, leaving it shorted no longer protects the system/charger from surges when plugged in, and provides no overvoltage protection.Comment
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