Units connected to GROVE port and battery issues

[antimix]

My M5Stack Core kept the small battery in good conditions for months (not using it) until I started to connect an ultrasonic unit to the groove port.
Basically I discovered that the 5V on the grove connector are DIRECTLY connected to the battery, and even if the Core is in deep sleep/off, there is still voltage on the pin that powers the ultrasonic unit. As result, leaving the Core turned off, but with the unit cable still connected to the grove port for weeks, slowly HARD drain the battery, until the battery is destroyed and then is not possible to recharge it any more.

• Is there a way to really TURN OFF the power on the grove / bus pins if there are cabled devices ?

[felmue]

Hello @antimix

I see the same on my M5Stack (Gray) - when I turn it off manually I still measure about 2 V on the Groove port.
In contrast when I do the same with an M5Core2 the Groove port is properly turned off when M5Core2 is turned off.

Since there is no full schematic for the M5Stack (Gray) it's hard to tell why the Groove port isn't fully turned off and if there is a way to really turn it off.

BTW: even with the Groove port not fully turned off the battery should not have been depleted completely as the battery has a built-in protection circuit which in theory should prevent under- or overvoltage.

Thanks
Felix