Charge voltage

[landdan]

I get 3.85v near the battery connector (see pic), but the voltage does not budge when connected to charger. I expected to see 4.4v. Why not?

Charger and cable are charging other phones just fine and apparently this one as well.

2022 Power

 

[Bla1ze]

get 3.85v near the battery co

A steady ~3.85 V generally means:

• Battery is roughly 40–60% charged
• The battery itself is healthy enough to hold voltage
• The PMIC is not pushing it into the CV phase yet

You will only see ~4.3–4.4 V when:

• The battery is near full
• The charger has transitioned into the constant-voltage phase
• The phone temperature and charge limits allow it

Even then, it often never reaches full max voltage due to battery-health preservation logic.

 

[landdan]

Did some more testing. With a USB test cable, I measured exactly 5V from unloaded charger. I was afraid to do this next test, but decided to go for it*. I disconnected the battery while the phone was connected to charger. Voltage at the pictured test point dropped to 0.7 and decayed to millivolts from there. The same thing happens when charger is not connected.

There must be another point where I can find the charger voltage unless the jack is damaged.

The phone kept working for almost 4 days in the great outdoors before going silent. The obvious explanation would be a dead battery. Maybe the phone became bricked somehow and no longer drew from battery.

*Many battery chargers have an unfiltered (spikey) output when unloaded, relying on the large capacitance of a battery to smooth the voltage. Those spikes could harm electronics without the voltage-limiting protection of a battery.

 

[landdan]

Update: I found the charger voltage at the point shown on this latest pic. (smaller arrow at left)
The 5V goes away when charger is disconnected. The 3.85 volts drops to 0.7v and decays when battery is disconnected. Voltage does not go up when charged overnight.

Is it common for lithium batteries to get stuck at half charge?

 

[mustang7757]

Sounds like you're experiencing battery degradation and not accepting a charge. You have the charger path 5V going in, so nothing with your charger. You can try a new battery, but just so you know, this is beyond most people's scope as we don't really take our phones apart to check these things, and a professional repair shop can handle this than most consumers.