Fixing Samsung A12 Charging Slowed Due to Low Temperature

 If you've plugged your customer's Samsung phone and met with a strange thermometer icon or a warning that the phone is "too cold to charge," that is a common error. This frustrating issue is known as a thermal error, and it's particularly common in models like the Samsung A12 (sm A125f). Many mobile technicians take the same model for repair in Samsung a12 charging slowed due to low temperature problem. This error is repairable with a bit of intelligence and the right tools.

Samsung A12 Charging Slow Problem Symptoms

🚨 Common Symptoms of the Thermal Error:

1. When pressing the phone's power button, the Phone displays a thermometer symbol inside a triangle.
2. Warning message: "Temperature is too low. Charging will resume when temperature returns to normal."

   

   Samsung A12 Charging error

   
   
3. The phone doesn't turn on, or when put on charge, it gets stuck on the battery symbol.
4. Most mobile technication perform shortcut technique to fix this error. They remove components from the phone circuit, but the error turns into fake charging.
5. When checking charging on a 6 port usb charger, Charging starts briefly (around 1.4A) and then drops.

Samsung A12 charger error

Why is My Samsung A12 Charging Slowly

Customers usually ask this question. To answer it, you can tell the customer that it seems that there is a problem with the sub-board circuit of your phone. This problem can also be caused by components. Give me permission to open the phone so that I can check it and tell you if any component is damaged or if there is a problem with the thermal circuit of the phone.

🧵 Root Cause: Faulty Thermal Circuit:

Samsung Galaxy phones monitor temperature using an NTC thermistor (Negative Temperature Coefficient resistor) that works with a fixed resistor to create a voltage divider circuit. If the NTC thermistor is damaged or reads incorrectly, the phone may think the battery is too cold (or hot) and halt charging as a safety precaution.

Components Involved:

1. R1: Fixed resistor (typically 100kΩ)
2. R2: NTC thermistor (also around 100kΩ at room temp)

why is my samsung a12 not charging

Both components send signals to the CPU IC in the phone via a thermal input line. Any irregularity triggers the error.

Here's a comprehensive step-by-step guide to understanding and resolving the thermal error issue.

Samsung A12 Charging Slow Problem Step-by-Step Repair Process

🔍 Step 1: Observe Charging Behavior

• Use a 6 port USB charging or DC power supply charging meter:
• Note the initial amp draw.
• See if the current drops quickly or stays steady.

Samsung A12 charging error problem solution manual

🌐 Step 2: Visual Inspection

• Open the device carefully.
• Locate the resistors near the mic section or charging port.
• Inspecting for damage, corrosion, or discoloration.

⚖️ Step 3: Voltage Check Using a Digital Multimeter:

• R1 (Fixed Resistor) should show ~1.8V.
• R2 (Thermistor) should show reduced voltage (~0.9V).
• If either side shows abnormal values, one of the components may be faulty.

How to measure resistors

🔢 Step 4: Resistance Measurement Switch Multimeter to Ohm Mode:

• R1: ~100kΩ
• R2 (NTC): ~100kΩ at 25°C; lower if it's been heated.
• If the thermistor reads <30kΩ at room temperature, it's defective.

Samsung A12 Slow Charging Jumper❌ What NOT to Do: Bypassing the Circuit

Some YouTubers' mobile phone technication suggests removing R1 and R2 completely to bypass the error. This may eliminate the thermal warning, but it causes a fake charging battery symbol to appear, but no real charge flows. It’s not a real fix and can harm the phone further.

samsung a12 slow charging jumper solution

Why is My Samsung A12 Charging Slowly Fix ✅ Proper Fix: Replace Faulty Components

• Replace R1 with a new 100kΩ resistor.
• Replace R2 with a proper NTC thermistor.

Can't you find the exact NTC? Use a fixed resistor between 47kΩ and 68kΩ as a temporary simulation to complete the voltage divider and remove the error. 

Find resistance by searching TH in schematic PDF

You can find this resistance from the schematic diagram of any Samsung mobile phone, J series, S series, or A series. You can take it from the scrap circuit you have and put it in your customer's circuit and fix his mobile.

Samsung A12 charging temperature solution

Download Samsung schematic diagram pdf here. To read and learn how to repair Samsung Galaxy phones. 

🎯 Final Test and Result Reconnect charger.

1. Charging current should stabilize around 1.4A.
2. No thermal error icons.
3. Battery % should increase over time.

Congratulations, the thermal error is gone, and your phone is back in action!

Some additional studying resources for my readers:

• Read the case study on Samsung Galaxy A12 not charging because cold
• How to Solve Charging Paused Battery Temperature too Low Error
• Understanding Samsung Slow Charging Issue read more

In conclusion: Encountering the Samsung A12 charging slowed due to low temperature error can be frustrating, but with the right knowledge and tools, it’s a fully repairable issue. By understanding the thermal circuit, checking the NTC thermistor, and replacing faulty components with correct resistance values, you can restore normal charging functionality. Always remember that diagnosing accurately and applying safe repair techniques are key to long-lasting results. If you're unsure, it's best to consult a trained technician to avoid further damage.

If this guide helped you, consider sharing it with other mobile repair enthusiasts. Understanding thermal circuitry and proper diagnostics can save you time and prevent further damage to your device.