820-02382 not seeing battery

[Serbentas]

Hi,
820-02382 (MacBook A2485 16" M1) not detecting battery. Battery sign has cross. However it works from battery but not charging and reporting incorrect data like charge remaining.
Any one any ideas please? Also fans are high/full speed

[mon2]

Measure with care the voltage to ground on each pin on the battery connector. Post each measurement.

[Serbentas]

J5151:
pin 4 (SMBUS_BATT_SDA) - 1.79V
pin 3 (SMBUS_BATT_SCL) - 1.69V
pin 1 (SYS_DETECT_L) - 0V

Battery gets 12V on + -

[mon2]

The SMBUS interface on the battery connector do operate @ 1v8 swing so the measured voltages are correct.

Can you share a screen pic of the battery details for your unit? Do you see the serial #, # of charge cycles, etc. correctly? If not, there is some fault here.

The communication is from a low voltage SMBUS that travels through a voltage level shifter to be compatible with the 1v8 SMBUS swing that is onboard the BMS board that is implanted inside of every battery pack. Perhaps the 1v2 side of the level shifter is not working but confirm your battery screen details.

Have you tested with another known good battery? Perhaps consider to source from Amazon and return it if it is not required.

Confirm the voltage to ground of the SYS_DETECT signal as per attached.

[Serbentas]

SYS_DETECT 3.8V
Will try to get another battery to test

[mon2]

Also run a diag on the board to understand the reason for the high fan spin which should a failure status of a sensor or the lack of that sensor’s ability to report back. If the sensor access times out then the fan will also enter turbo mode.

[Serbentas]

Tried 3 batteries, one of them new, all shows that. They work on other Macs and display all info correctly. So Mac fails to read.
Is U5200 faulty?

[mon2]

Is U5200 faulty?

No, because your logic board is booting fine which means that this buck / boost regulator is correctly creating the PPBUS_AON_REG rail. The battery communication is failing which is over the SMBUS interface.

Review the level shifters that are used in this circuit @ UD102. Carefully measure the voltage to ground of:

I2C_SMC_PWR_SCL
I2C_SMC_PWR_SDA

You have at least the battery not being properly detected but the same cluster of SMBUS slave devices are most likely raising the temp sensor fault resulting in the turbo high fan speed.

[Serbentas]

All looks good.
Voltage on both 1.22

[Serbentas]

Is this the end of the road?

[mon2]

They work on other Macs

Same model?

What did the HW diags report?

Use Apple Diagnostics to test your Mac - Apple Support (CA)

[Serbentas]

Diagnostics report only 'might be a problem with fans'

[Serbentas]

Yes, same models

[mon2]

Run coconut battery to see if it reports anything different:

coconutBattery 3.9 - by coconut-flavour.com


What is the voltage to ground of each of the following?

I2C_KBD_SCL
I2C_KBD_SDA

I2C_TPAD_CONN_SCL
I2C_TPAD_CONN_SDA

[Serbentas]

I have battery tool for macs and it read battery as normal 56% charge, cycle count etc
I2C_KBD_SCL/SDA - both 1.8 V

And there are no such lines on this board as:
I2C_TPAD_CONN_SCL
I2C_TPAD_CONN_SDA

[Serbentas]

Oops.Sorry. Looking at the wrong schematic
I2C_TPAD_CONN_SCL
I2C_TPAD_CONN_SDA

Both 1.85V

[mon2]

Try a DFU:

https://maclovin.org/blog-native/202...0documentation.

[Serbentas]

Done that already

[mon2]

Did that work for you without issues? What are the test results from the coconut battery tool?

[mon2]

If you take your other known good batteries and run your battery tool, are the results consistent with the strength or charge of the battery? The number of charge cycles are correct? The same non-working battery on this board is detected properly on another identical logic board?

Be sure to confirm your battery contacts on the non-working board.