DELL XPS 15-9530 LA-9941P VAUB0 slow charging

[Rainbow]

After plugging the AC adapter (original 130W, detected properly in BIOS) battery starts charging. Battery voltage goes up to 12.3-12.4V but then slowly decreases to 11.5V. Also when the laptop is turned on, the voltage goes up and the cycle repeats. Maybe the EC is telling the charger to reduce the voltage/current (because of what?).

Linux (in /sys/class/power_supply/BAT1/uevent) says that the charging power goes up to around 20W and then down to only 1.5W.

The AC adapter voltage remains at 19.5-19.6V.
With the battery disconnected, there's 13.4V on the battery connector.

The battery is new (non-DELL). There was already a non-DELL battery installed but was completely bad (bloated, overdischarged). It lasted only about 2 years so maybe the charging problem was already present.

[mon2]

Re: DELL XPS 15-9530 LA-9941P VAUB0 slow charging

Check if the battery current sensor is o nboard at pu202. Remove all power and configure the meter to resistance mode. Measure the resistance between pins 4 & 5 at the pads on pu202. what is the measurement?

[Rainbow]

Re: DELL XPS 15-9530 LA-9941P VAUB0 slow charging

PU202 is not populated. Pins 4 & 5 are connected to PR219 which seems to be OK (zero resistance). Voltage at PR219 is around 22mV (=2.2A), then decreases to 1.3mV (=0.13A). So the current sensing seems to work fine.

Looks like I'll need to look at the SMBus communication.

[mon2]

Re: DELL XPS 15-9530 LA-9941P VAUB0 slow charging

Check the voltage to ground of the SMBus connections (SDA / SCL) lines on the battery connector.

Is the battery detected in the OS? Can you extract details of the battery in Windows?

[Rainbow]

Re: DELL XPS 15-9530 LA-9941P VAUB0 slow charging

Communication works. The battery is reporting charging current 2640mA. EC sets charger to 2640mA but then lowers it to 611mA. Maybe the battery is bad, reporting only 764mA?

write(2C,00,20,00,2C,5C,00,38)
write(0B,0D)
read(0B,15,00)
write(0B,1C)
read(0B,27,10)
write(0B,2E)
read(0B,27,10)
write(0B,00)
read(0B,88,4D)
write(0B,2E,00,A7)
write(0B,2E)
read(0B,01,00)
write(0B,36,04,42,A8,2C,E4)
write(0B,2D,08,04,00,00,00,00,00,00,00)
write(0B,16)
read(0B,C0,00)
write(0B,36)
write(0B,20)
read(0B,0B,53,4D,50,2D,4C,49,53,32,2E,37,31)
write(0B,21)
read(0B,0D,44,45,4C,4C,20,48,37,36,4D,59,33,39,51)
write(0B,0D)
read(0B,15,00)
write(09,12)
read(09,CC,E4)
write(0B,36)
read(0B,04,1F,DF,43,83)
write(0B,16)
read(0B,C0,00)
write(0B,21)
read(0B,0D,44,45,4C,4C,20,48,37,36,4D,59,33,39,51)
write(0B,0D)
read(0B,15,00)
write(0B,15)
read(0B,38,31)
write(0B,08)
read(0B,A6,0B)
write(0B,0F)
read(0B,26,04)
write(0B,03)
read(0B,00,60)
write(0B,03,00,E0)
write(0B,19)
read(0B,5C,2B)
write(0B,0A)
read(0B,00,00)
write(0B,0B)
read(0B,08,00)
write(0B,09)
read(0B,E9,2D)
write(0B,14)
read(0B,50,0A)		BAT ChargingCurrent == 2640mA
write(0B,18)
read(0B,D9,17)
write(0B,10)
read(0B,BD,16)
write(0B,1B)
read(0B,D9,52)
write(0B,00)
read(0B,80,41)
write(0B,00,08,00)
write(0B,00)
read(0B,88,41)
write(0B,17)
read(0B,00,00)
write(0B,3B)
read(0B,59,0F)
write(0B,3A)
read(0B,56,0F)
write(0B,39)
read(0B,3B,0F)
write(0B,38)
read(0B,90,47)
write(09,3F,00,18)
write(09,15,00,00)
write(09,3E,00,24)
write(09,12,CC,E4)
write(09,15,38,31)	MaxChargeVoltage = 12600mV
write(09,14,00,00)	ChargeCurrent = 0
write(0B,16)
read(0B,C0,00)
write(09,3F)
read(09,00,18)
write(09,15,38,31)	MaxChargeVoltage = 12600mV
write(09,14,00,00)	ChargeCurrent = 0
write(0B,21)
read(0B,0D,44,45,4C,4C,20,48,37,36,4D,59,33,39,51)
write(0B,0D)
read(0B,15,00)
write(0B,15)
read(0B,38,31)
write(0B,08)
read(0B,A6,0B)
write(0B,0F)
read(0B,9B,04)
write(0B,03)
read(0B,00,E0)
write(0B,0A)
read(0B,00,00)
write(0B,0B)
read(0B,07,00)
write(09,15,38,31)	MaxChargeVoltage = 12600mV
write(09,14,00,00)	ChargeCurrent = 0
write(0B,09)
read(0B,E9,2D)
write(0B,14)
read(0B,50,0A)		BAT ChargingCurrent == 2640mA
write(0B,10)
read(0B,BD,16)
write(0B,1C)
read(0B,27,10)
write(0B,00)
read(0B,88,01)
write(0B,17)
read(0B,00,00)
write(0B,3B)
read(0B,59,0F)
write(0B,3A)
read(0B,56,0F)
write(09,14)
read(09,00,00)
write(09,15,38,31)	MaxChargeVoltage = 12600mV
write(09,14,00,00)	ChargeCurrent = 0
write(0B,39)
read(0B,3B,0F)
write(0B,38)
read(0B,90,47)
write(09,15,38,31)	MaxChargeVoltage = 12600mV
write(09,14,00,00)	ChargeCurrent = 0
write(0B,16)
read(0B,C0,00)
write(0B,21)
read(0B,0D,44,45,4C,4C,20,48,37,36,4D,59,33,39,51)
write(0B,0D)
read(0B,15,00)
write(0B,15)
read(0B,38,31)
write(09,15)
read(09,30,31)
write(09,15,38,31)	MaxChargeVoltage = 12600mV
write(09,14,00,00)	ChargeCurrent = 0
write(0B,08)
read(0B,A6,0B)
write(0B,0F)
read(0B,9B,04)
write(0B,03)
read(0B,00,E0)
write(0B,0A)
read(0B,00,00)
write(0B,0B)
read(0B,05,00)
write(0B,09)
read(0B,E9,2D)
write(0B,14)		BAT ChargingCurrent == 2640mA
read(0B,50,0A)
write(0B,10)
read(0B,BD,16)
write(09,15,38,31)	MaxChargeVoltage = 12600mV
write(09,14,50,0A)	ChargeCurrent = 2640mA
write(0B,1C)
read(0B,27,10)		serial number
write(0B,00)
read(0B,88,01)		mfg.access
write(0B,17)
read(0B,00,00)		cycle count
write(0B,3B)
read(0B,C4,0F)		cell voltage(?) = 4036mV
write(0B,3A)
read(0B,BD,0F)		cell voltage(?) = 4029mV
write(0B,0A)
read(0B,FC,02)		current = 764mA
write(0B,08)
read(0B,A6,0B)		temperature = 25.05 C
write(0B,39)
read(0B,D0,0F)		cell voltage(?) = 4048mV
write(0B,38)
read(0B,90,47)		???
write(09,3E)
read(09,00,24)		???
write(09,15,38,31)	MaxChargeVoltage = 12600mV
write(09,14,63,02)	ChargeCurrent = 611mA
write(0B,0A)
read(0B,27,06)
write(0B,08)
read(0B,A6,0B)
write(09,15,38,31)	MaxChargeVoltage = 12600mV
write(09,14,63,02)	ChargeCurrent = 611mA
write(0B,16)
read(0B,80,00)
write(0B,21)
read(0B,0D,44,45,4C,4C,20,48,37,36,4D,59,33,39,51)
write(0B,0D)
read(0B,15,00)
write(0B,15)
read(0B,38,31)
write(0B,0A)
read(0B,49,02)
write(0B,08)
read(0B,A6,0B)
write(0B,08)
read(0B,A6,0B)
write(0B,0F)
read(0B,9C,04)
write(0B,03)
read(0B,00,E0)
write(09,12)
read(09,CC,E4)
write(09,15,38,31)	MaxChargeVoltage = 12600mV
write(09,14,63,02)	ChargeCurrent = 611mA
write(0B,0A)
read(0B,48,02)
write(0B,0B)
read(0B,B2,00)
write(0B,09)
read(0B,C0,2E)
write(0B,14)		BAT ChargingCurrent == 2640mA
read(0B,50,0A)
write(0B,10)
read(0B,BD,16)
write(0B,0A)
read(0B,48,02)
write(0B,08)
read(0B,A6,0B)
write(0B,1C)
read(0B,27,10)
write(0B,00,00,00)
write(0B,00)
read(0B,80,01)

0B = battery
09 = charger

[mon2]

Re: DELL XPS 15-9530 LA-9941P VAUB0 slow charging

1) Do test with a known good battery - Amazon?

2) Do review the current sense circuits on this same leg to confirm the resistance between the P and N pins on the charger IC match the values of the schematic. If the resistance is not matching, the charger IC will assume too high of a current draw and then will throttle the current.

[Rainbow]

Re: DELL XPS 15-9530 LA-9941P VAUB0 slow charging

Charger (bq24715) register 0x12 is set to 0xE4CC, which means fixed IOUT pin with "40x adapter current amplifier output" value. This pin is connected (as ADP_I) to EC. It goes up to 0.6V after plugging, then decreases as charging slows down. 0.6V seems to be OK (0.6V/40 = 0.015V, Rsense=0.01R, I=0.015V/0.01R = 1.5A).

As the current is reduced by a command from EC, it rules out the charger.

[Rainbow]

Re: DELL XPS 15-9530 LA-9941P VAUB0 slow charging

Bought the cheapest battery available (only 4400mAh instead of 5500mAh) in a local shop. The connector is very hard to plug but guess what? It's charging!

It was completely discharged (around 8V) but the voltage is slowly rising (currently at 11.35V), Linux shows 22W charing power and percentage rises (currently 10%).

The first "new" battery was clearly bad - high internal resistance. The 12.3 voltage is too high (at the same current) and looks like there's some charging algorithm in EC that can detect that and reduce the current.

[Rainbow]

Re: DELL XPS 15-9530 LA-9941P VAUB0 slow charging

It worked exactly once. The battery charged to 100% and then I turned off the laptop and disconnected adapter.

Now I powered it up and the battery was only around 10%!
Connected adapter, the voltage rised to about 12.4V, charging power started around 20W and keeps decreasing. Much less than with the first battery, it's now around 11W and battery at 24% but it still does not look right.

Another crappy battery?

[Rainbow]

Re: DELL XPS 15-9530 LA-9941P VAUB0 slow charging

Yes, it was another crap. Discharge lasted only 1 hour (with CPU loaded), then charged normally again (voltage rising slowly).

Bought another battery. Looks same as the first one except one sticker - but this one works. And seems to work well - it's charging over 30W and charges up to 13.2V. Looks like it has 4.4V cells.