Minimum battery voltage to allow charging (nPM1300)

[Trym Ullestad]

We tried connecting a deeply discharged lithium-ion battery to the nPM1300-EK to see how it would charge, but we weren't allowed to enable charging as we got the following errors:

Charger errors: VBATLOW, VTRICKLE
Sensor errors: SENSORRECHARGE, SENSORVTRICKLE, SENSORVBATLOW

I believe the battery was around 1.5V when we tried charging and its fully charged voltage cutoff would be 4.35V.
I think I read somewhere that the operating ranges for the battery was down to 2.3V, does this mean that a battery under 2.3V will not be allowed to charge?

The settings of interest were:
Vterm = 4.35V
Ichg = 326mA
Enable Recharging = False
Iterm = 10%
Vtrickle_fast = 2.5V
POF Enabled = False

We tried connecting another battery at around 3.5V which worked fine so I doubt there were any issues with our configuration.
The NTC "measured" 25 degrees so it should not be a problem either.

[Andy Sinclair]

Hi Trym.

Charging below the VBATLOW threshold can be enabled in devicetree.
Could you try adding this option to see if this fixes your issue?

vbatlow-charge-enable:
    type: boolean
    description: |
      Allow charging when below the vbatlow threshold.

[Trym Ullestad]

We have not flashed a custom firmware to the nPM1300-EK; we only connected it and flashed the firmware when opening nPM PowerUP for the first time.
Is this setting available through PowerUP or is the firmware for the host chip available somewhere?

[Andy Sinclair]

Ah I see, sorry about that.
The devicetree option is for adding this option to a Zephyr application running on a separate development kit, not for evaluating using nPM Powerup. 

This option does not have a GUI interface in PowerUp, however you can set it directly using the serial terminal interface.

The `npm1300_reg` shell command supports direct register writes on the device, so you can enable it that way.

The required command is:

npm1300_reg 0x350 1

[Trym Ullestad]

Thank you so much! I got it to work after sending: 

npm_reg 0x350 1

It didn't work for me to send the command you suggested; for me that command tried to write 0x50 to register 0x0000. I assumed you wanted to write 1 to an address offset by 0x50 from BCHARGER (address 0x300). The command I wrote above returned a confirmation that address 0x350 got a write of 1 to it:

shell:~$ > npm1300_reg 0x350 1
npm1300_reg 0x350 1
Write *0x0350=0x01

[Andy Sinclair]

That's great :-) 
I was guessing without HW to hand, so thanks a lot for working out the correct incantation.
I'll update my answer to the correct command.

[dani_martin]

Hey this information was very useful for me!!! But I don't see that register in the user manual. From BCHARGER (0x300) I only see registers up to 0x3C. I don't see any 0x50.....