Bq24195 power management, battery backup fails

Official Hardware Portenta Family Portenta Max Carrier
1

Hi,
I'm using a Portenta Max Carrier with a Portenta H7 for a development at work. It is required that the board remains running from the 18650 battery when the DC input voltage drops or fails. Unfortunately this right now doesn't work for me. If have a 3500mAh battery plugged to the board and a 12V wall adapter is powering the board.

For what I discovered is that the BQ24195 (U11) doesn't boost up the battery voltage to the PMID pin (+5V_BQ) when I remove the DC input voltage at the VBUS pins (+5V_MPM).

I tried several register settings with the PMIC- and bq24195 libraries, but I didn't get it to work the right way. In general, is it meant to work out of the box, or do I have to configure the power management IC in source code to enable the battery backup?

Did somebody face similar issues and got it to work?

Thank for your help.

regards
Holger

2

So, after some more tests, I figured out that I only get around 3.5V on the PMID output pin of U11. Can somebody reproduce this issue?

3

Have you used a proper (like SkyRC) charger/tester to determine if the 18650 is fake or not (it is the most faked item on AE)

4

No, I did not as I don't have a tester. But I also did not buy it on AE, but on a German distributor. This is the battery I have:

5

I managed to get it to work partly. It seems that in standard configuration the BoostVoltage on PMID is disabled (therefore 3.5V) and the battery is charging when VBUS is connected. If you read the PG_STAT flag of REG08 System Status Register then one can check if VBUS is applied or not. Once the VBUS voltage is removed PG_STAT becomes 0 and I call the EnableBoostMode() function and the 5.1V appear on PMID.

So far so good, but this only works if the H7 is properly powered by the onboard USB (on the H7 board) . I guess this is because of the 200ms voltage drop of the power management ic. Is there any chance to get rid of this? What bothers me, is that on the product page of the Portenta Max Carrier is written

Max Carrier can be powered via external supply (6-36V) or battery via the onboard 18650 Li-ion battery connector with 3.7V battery charger.

Does that mean, that the carrier board can be powered by the battery, but the H7 processor board not? If so, then this would be more or less useless to me....

6

The BQ24195 should handle battery backup automatically, but in some cases, default register settings might not enable boost mode properly. Double-check the OTG and boost settings via I²C, especially REG01 and REG07. I’ve seen similar behavior resolved by explicitly enabling boost mode in code. Hope this helps!