I have had no problems with the Samsung EP-TA800 USB-C charger so far. Quite the opposite — charging is very fast, and according to the kernel logs, the phone and charger negotiate USB PD PPS correctly and appear to communicate exactly as intended.
I cannot make any long-term claims about battery health, but technically the charging process looks normal and well controlled.
I can see some improvements after 5.2.0.18 update, in car i use dac with charger port ADA-HCPD USB-C - Hi-Res DAC audio adapter PD 60 W | AXAGON
Before update i have seen maximum current about 400mA, now it charges 2600mA+, well did not checked logs but i have patched patch ‘Powerdrain on statusbar’ by @nephros so can see the charging current as well
Charging with EP-TA-800 charger usb-c.
With 5.2.0.17 Battery Buddy showed over 600 mA current input.
+Battery had 22 % in the start.
+After update to 5.2.0.18 + on charging: Battery had 19-20 %
With 5.2.0.18 now, Battery Buddy showed in the start 580 mA, then it dropped to around 280 to 340 mA.
I stopped test at 18 %. JP2 off again.
Thus charging not able to increase charge %.
JP2 was in flight mode or totally off. No difference.
EP-TA-800 charged tablet very fast as earlier. And is charging again at the moment.
Ps. Tested two conductors:
Of Belkin: usb-c - usb-c.
Old one: usb-A + adapter - usb-c.
No differences .
With current you should mentioned the charge percentage (battery voltage is even better) because it matters.
Technical explanation: when battery voltage is reaching the threshold (about 4.4V) the charging switches from constant current method to constant voltage. Which means that the current drops.
Va bene. I added the % values.
Today I happened to have a 30W MacBook Air charger next to me so I felt like it’s a good opportunity to test that as well.
Not only it worked perfectly, but the charging speed was actually much better! It took 1.5H from 35 to 100%, while the 20W charger would take about 3.5H for some reason.
Not sure if the latest update had anything to do with that, but I guess I’ll see that in a few days where I’ll charge it again.
Yes there must be some improvements in .
18 update as i mentioned USB-C to USB-C charging does not work reliably on my Jolla Phone 2026 - #22 by koza
Maybe this will be useful for others testing chargers with the JP2026 as well.
I made a small native Sailfish OS utility for Jolla Phone 2026 which displays battery and charging information in a simple graphical UI.
The main reason was the rather interesting USB-C charging behaviour of the JP2026. Instead of repeatedly checking /sys/class/power_supply/ from the shell, FelisBattery shows the relevant information directly in the application.
It displays battery percentage and status, instantaneous and average current, voltage, calculated power, temperature, charge/full/design capacity, battery health and cycle count.
For charging diagnostics it also shows the detected power source type, active charging path, input voltage/current/power where available, and whether the phone is using standard or direct charging.
There is also a separate technical-information page with the raw power-supply data, and the diagnostic output can be copied to the clipboard for forum posts or bug reports.
FelisBattery is read-only. It does not change charging settings or write anything to sysfs. It runs without sandboxing because it needs access to the low-level power-supply information.
It is designed and tested for Jolla Phone 2026. Other devices are unsupported, but you are of course welcome to try it.
GitHub: GitHub - MiPal666/FelisBattery: FelisBattery displays battery state and detailed charger diagnostics. Detailed charger-path diagnostics are designed and tested for Jolla Phone 2026 · GitHub
OpenRepos: Felis Battery | OpenRepos.net — Community Repository System
My USB- to USB-C charging (Samsung 25W PD) did not work under 5.0.2.17. With 5.2.018 it starts the same way with howering around 0mA charging (-300 to +300). After maybe 10 secs or so it qickly rises to 2700 mA (while the screen is on).
Tested fine Felisbattery with different chargers + conductors:
In all cases:
All cases were detected that something was connected (DCP).
Input current: - (Not detected value).
Input power: - (Not detected value).
JP2 has now 12 % charge.
No use to continue anymore. Set off again.
Hard to belive that all my conductors are full shit.
I have tested quite a few USB-C chargers and cables by now. Only one USB-C charger works reliably with my JP2026, and I happened to already have that one at home.
With the others, the phone clearly detects that a power source is connected, but charging either does not start at all or oscillates between charging and discharging. FelisBattery shows the source being detected, but no usable input current/power and no stable charging path.
So at this point I find it rather unlikely that all of my USB-C chargers and cables are simply bad or incompatible.
Since one USB-C charger works perfectly and many others are at least detected by the phone, I suspect the problem is somewhere in the JP2026/MediaTek charging negotiation path, rather than all those chargers and cables being faulty.
Do note that it in last release notes that mention improvement on that doesn’t say fixed:
Logs are more then welcome.
Sure, I understand that it says improved, not fixed.
My point was only that with several different USB-C chargers/cables failing while one charger works reliably, this does not look like a simple bad-cable problem to me.
I’ll be happy to provide logs. I can capture a failed USB-C charging attempt and, for comparison, one with the charger that works reliably. Just let me know which logs would be most useful.
One more data point: I bought a second unit of the same Samsung 25W PD charger that already worked with my JP2026, and the second one works as well. So in my case this appears to be related to charger type/model compatibility rather than an individual faulty charger.
I had this issue with my XA2 many years ago but not with the Jolla Phone fortunately.
My currently preferred charger is a Baseus GaN3 Pro Desktop Fast Charger 100W CCDK100UE. USB-PD works with that reliably.
I’m pretty sure they’ll help. More about logs in the docs.
I suspect that it’s connected with PD, QC negotiating. Different versions of those negotiate differently and edge cases are also different. It might also be that Mediatek has some issues regarding negotiating but they should be mentioned in Errata.
I hope for a solution soon.
Any USB-C charger should be safe. The battery limits part of charging is controlled by phone anyway.
The issue with JP charging is that the current in some cases stays very low. That is safe to use but annoying to wait.
Do note that in the other topic the Jolla developer @mal is visibly active.
Why does thw report show full capasity to be 3769 mAh instead of 5450mAh
I have no problem with battery, lasts long etc .
FelisBattery 0.1.2
Updated: 2026-10-04 17:06:20
JP2026 charger diagnostics: available
Battery 39 %, Charging
Battery: 3.994 V / 2.57 A / 10.26 W
Charging: Direct charging / SDP
Input: 8.221 V / 1.49 A / 12.22 W
Temperature: 34.5 °C
===== battery =====
DEVTYPE=power_supply
POWER_SUPPLY_NAME=battery
POWER_SUPPLY_TYPE=Battery
POWER_SUPPLY_STATUS=Charging
POWER_SUPPLY_HEALTH=Good
POWER_SUPPLY_PRESENT=1
POWER_SUPPLY_TECHNOLOGY=Li-ion
POWER_SUPPLY_CYCLE_COUNT=81
POWER_SUPPLY_CAPACITY=39
POWER_SUPPLY_CURRENT_NOW=2568600
POWER_SUPPLY_CURRENT_AVG=2589000
POWER_SUPPLY_VOLTAGE_NOW=3994000
POWER_SUPPLY_CHARGE_FULL=3760000
POWER_SUPPLY_CHARGE_COUNTER=1466400
POWER_SUPPLY_TEMP=345
POWER_SUPPLY_CAPACITY_LEVEL=Normal
POWER_SUPPLY_TIME_TO_FULL_NOW=3189
POWER_SUPPLY_CHARGE_FULL_DESIGN=3760000
POWER_SUPPLY_CONSTANT_CHARGE_VOLTAGE=4520000
===== mt6720-gauge =====
DEVTYPE=power_supply
POWER_SUPPLY_NAME=mt6720-gauge
POWER_SUPPLY_TYPE=Unknown
POWER_SUPPLY_PRESENT=0
POWER_SUPPLY_ONLINE=0
POWER_SUPPLY_CURRENT_NOW=2650200
POWER_SUPPLY_CURRENT_MAX=-23474
POWER_SUPPLY_VOLTAGE_NOW=3997000
POWER_SUPPLY_ENERGY_EMPTY=0
POWER_SUPPLY_ENERGY_FULL_DESIGN=55662
POWER_SUPPLY_ENERGY_FULL=55662
POWER_SUPPLY_ENERGY_NOW=3876
POWER_SUPPLY_CAPACITY_LEVEL=3905
POWER_SUPPLY_TEMP=340
===== mtk-master-charger =====
DEVTYPE=power_supply
POWER_SUPPLY_NAME=mtk-master-charger
POWER_SUPPLY_TYPE=Unknown
POWER_SUPPLY_ONLINE=1
POWER_SUPPLY_PRESENT=1
POWER_SUPPLY_VOLTAGE_MAX=1
POWER_SUPPLY_VOLTAGE_NOW=8221
POWER_SUPPLY_TEMP=460
POWER_SUPPLY_CONSTANT_CHARGE_CURRENT_MAX=-1
POWER_SUPPLY_INPUT_CURRENT_LIMIT=-1
POWER_SUPPLY_VOLTAGE_BOOT=0
POWER_SUPPLY_USB_TYPE=[Unknown] SDP DCP CDP PD PD_PPS
POWER_SUPPLY_CHARGE_NOW=4009000
POWER_SUPPLY_POWER_NOW=4009000
===== mtk-mst-div-chg =====
DEVTYPE=power_supply
POWER_SUPPLY_NAME=mtk-mst-div-chg
POWER_SUPPLY_TYPE=Unknown
POWER_SUPPLY_ONLINE=0
POWER_SUPPLY_PRESENT=0
POWER_SUPPLY_VOLTAGE_MAX=1
POWER_SUPPLY_VOLTAGE_NOW=8224
POWER_SUPPLY_TEMP=0
POWER_SUPPLY_CONSTANT_CHARGE_CURRENT_MAX=-1
POWER_SUPPLY_INPUT_CURRENT_LIMIT=-1
POWER_SUPPLY_VOLTAGE_BOOT=-95
POWER_SUPPLY_USB_TYPE=[Unknown] SDP DCP CDP PD PD_PPS
POWER_SUPPLY_CHARGE_NOW=4008000
POWER_SUPPLY_POWER_NOW=4001000
===== mtk-mst-hvdiv-chg =====
DEVTYPE=power_supply
POWER_SUPPLY_NAME=mtk-mst-hvdiv-chg
POWER_SUPPLY_TYPE=Unknown
POWER_SUPPLY_ONLINE=0
POWER_SUPPLY_PRESENT=0
POWER_SUPPLY_VOLTAGE_MAX=1
POWER_SUPPLY_VOLTAGE_NOW=8224
POWER_SUPPLY_TEMP=0
POWER_SUPPLY_CONSTANT_CHARGE_CURRENT_MAX=-1
POWER_SUPPLY_INPUT_CURRENT_LIMIT=-1
POWER_SUPPLY_VOLTAGE_BOOT=-95
POWER_SUPPLY_USB_TYPE=[Unknown] SDP DCP CDP PD PD_PPS
POWER_SUPPLY_CHARGE_NOW=4004000
POWER_SUPPLY_POWER_NOW=4013000
===== mtk-slave-charger =====
DEVTYPE=power_supply
POWER_SUPPLY_NAME=mtk-slave-charger
POWER_SUPPLY_TYPE=Unknown
POWER_SUPPLY_ONLINE=1
POWER_SUPPLY_PRESENT=0
POWER_SUPPLY_VOLTAGE_MAX=1
POWER_SUPPLY_VOLTAGE_NOW=8232
POWER_SUPPLY_TEMP=0
POWER_SUPPLY_CONSTANT_CHARGE_CURRENT_MAX=-1
POWER_SUPPLY_INPUT_CURRENT_LIMIT=-1
POWER_SUPPLY_VOLTAGE_BOOT=-95
POWER_SUPPLY_USB_TYPE=[Unknown] SDP DCP CDP PD PD_PPS
POWER_SUPPLY_CHARGE_NOW=4001000
POWER_SUPPLY_POWER_NOW=4010000
===== mtk-slv-div-chg =====
DEVTYPE=power_supply
POWER_SUPPLY_NAME=mtk-slv-div-chg
POWER_SUPPLY_TYPE=Unknown
POWER_SUPPLY_ONLINE=0
POWER_SUPPLY_PRESENT=0
POWER_SUPPLY_VOLTAGE_MAX=1
POWER_SUPPLY_VOLTAGE_NOW=8221
POWER_SUPPLY_TEMP=0
POWER_SUPPLY_CONSTANT_CHARGE_CURRENT_MAX=-1
POWER_SUPPLY_INPUT_CURRENT_LIMIT=-1
POWER_SUPPLY_VOLTAGE_BOOT=-95
POWER_SUPPLY_USB_TYPE=[Unknown] SDP DCP CDP PD PD_PPS
POWER_SUPPLY_CHARGE_NOW=4004000
POWER_SUPPLY_POWER_NOW=4007000
===== mtk-slv-hvdiv-chg =====
DEVTYPE=power_supply
POWER_SUPPLY_NAME=mtk-slv-hvdiv-chg
POWER_SUPPLY_TYPE=Unknown
POWER_SUPPLY_ONLINE=0
POWER_SUPPLY_PRESENT=0
POWER_SUPPLY_VOLTAGE_MAX=1
POWER_SUPPLY_VOLTAGE_NOW=8221
POWER_SUPPLY_TEMP=0
POWER_SUPPLY_CONSTANT_CHARGE_CURRENT_MAX=-1
POWER_SUPPLY_INPUT_CURRENT_LIMIT=-1
POWER_SUPPLY_VOLTAGE_BOOT=-95
POWER_SUPPLY_USB_TYPE=[Unknown] SDP DCP CDP PD PD_PPS
POWER_SUPPLY_CHARGE_NOW=4009000
POWER_SUPPLY_POWER_NOW=4007000
===== primary_chg =====
DEVTYPE=power_supply
OF_NAME=chg
OF_FULLNAME=/soc/i2c@11282000/mt6720@34/chg
OF_COMPATIBLE_0=mediatek,mt6720-charger
OF_COMPATIBLE_N=1
POWER_SUPPLY_NAME=primary_chg
POWER_SUPPLY_TYPE=USB
POWER_SUPPLY_MANUFACTURER=Mediatek
POWER_SUPPLY_ONLINE=2
POWER_SUPPLY_STATUS=Not charging
POWER_SUPPLY_CONSTANT_CHARGE_CURRENT=3000000
POWER_SUPPLY_CONSTANT_CHARGE_CURRENT_MAX=3150000
POWER_SUPPLY_CONSTANT_CHARGE_VOLTAGE=4520000
POWER_SUPPLY_CONSTANT_CHARGE_VOLTAGE_MAX=4850000
POWER_SUPPLY_INPUT_CURRENT_LIMIT=500000
POWER_SUPPLY_INPUT_VOLTAGE_LIMIT=4200000
POWER_SUPPLY_PRECHARGE_CURRENT=1000000
POWER_SUPPLY_CHARGE_TERM_CURRENT=300000
POWER_SUPPLY_USB_TYPE=Unknown [SDP] DCP CDP
POWER_SUPPLY_CURRENT_MAX=500000
POWER_SUPPLY_VOLTAGE_MAX=5000000
POWER_SUPPLY_CALIBRATE=3999
POWER_SUPPLY_ENERGY_EMPTY=0
POWER_SUPPLY_TYPE=USB
===== primary_dvchg =====
DEVTYPE=power_supply
OF_NAME=div2
OF_FULLNAME=/soc/i2c@11282000/mt6720@34/div2
OF_COMPATIBLE_0=mediatek,mt6720-div2
OF_COMPATIBLE_N=1
POWER_SUPPLY_NAME=primary_dvchg
POWER_SUPPLY_TYPE=USB
POWER_SUPPLY_STATUS=Charging
POWER_SUPPLY_HEALTH=Good
POWER_SUPPLY_ONLINE=1
POWER_SUPPLY_VOLTAGE_MAX=9800000
POWER_SUPPLY_VOLTAGE_NOW=8228000
POWER_SUPPLY_CURRENT_MAX=5000000
POWER_SUPPLY_CURRENT_NOW=1455000
POWER_SUPPLY_CONSTANT_CHARGE_VOLTAGE_MAX=4950000
POWER_SUPPLY_TEMP=460
POWER_SUPPLY_MODEL_NAME=MT6720
POWER_SUPPLY_MANUFACTURER=Richtek Technology Corp.
FelisBattery does not calculate the 3760 mAh value itself. It displays exactly what the JP2026 kernel reports:
POWER_SUPPLY_CHARGE_FULL=3760000
POWER_SUPPLY_CHARGE_FULL_DESIGN=3760000
These values are reported in µAh, so FelisBattery displays them as 3760 mAh.
The physical battery is specified by Jolla as 5450 mAh, so there is clearly a difference between the advertised battery capacity and what the current battery/power-supply driver exposes through sysfs.
I have seen the same 3760 mAh values on other JP2026 devices as well, so this does not appear to indicate battery degradation. In your case CHARGE_FULL and CHARGE_FULL_DESIGN are identical, which is also why FelisBattery reports 100% battery condition.
I don’t currently know why the MediaTek/Jolla battery driver uses 3760 mAh internally. FelisBattery intentionally reports the kernel values without trying to “correct” them.
