How many volts should a charger put out?

Voltage should match the device’s requirements. For most smartphones and small devices, that means 5 volts; many newer devices use higher voltages negotiated via USB Power Delivery (commonly 9V, 12V, or 20V). Laptops typically require about 19V or 20V.

Understanding voltage and charging basics

Charging works through a negotiation between charger and device. The device signals the correct voltage it can safely accept, and the charger supplies that voltage within its capabilities. Using a voltage higher than what the device can safely handle can damage the battery or circuitry, while too low a voltage may charge slowly or not at all. USB Power Delivery (PD) and related fast-charging standards enable devices to request the appropriate voltage dynamically.

Common standards you’ll encounter

In everyday charging, you’ll encounter a handful of standard voltages. The following list highlights the typical output voltages used by consumer chargers and the devices that accept them.

• 5V: The classic USB charging voltage found on older devices and standard charging bricks.


• 9V: Used by some fast-charging profiles to increase speed without excessive current.


• 12V: Another fast-charging level supported by several devices with compatible chargers.


• 15V: Supported by certain fast-charging protocols for specific devices.


• 20V: Common for USB-C Power Delivery laptops and larger devices, enabling higher power delivery.

These voltages are often delivered via negotiation between the charger and device. Many chargers advertise multiple voltages and indicate support for PD or PPS to match the device’s needs. Note that USB PD 3.1 and related standards have expanded capabilities for higher-power uses, including voltages up to 48V in very specific, high-power scenarios.

How to verify your device’s voltage requirements

To avoid damage, confirm the exact voltage required by your device before buying a charger. Use labels on the device or refer to the official manual or manufacturer site.

• Check the device’s documentation or the label on the device itself for “Input: V” or “Output: V” specifications.


• Examine the original charger that came with the device to see its output voltage and wattage.


• Look up the model online and review the official specifications from the manufacturer.


• If you see “PD” or “PPS” on a charger, ensure the charger and the cable support the device’s negotiation protocol for the correct voltage.


• When in doubt, start with a charger that matches the device’s stated voltage and, if possible, supports the same charging standard (e.g., USB PD) for safe negotiation.

Following these steps helps ensure you supply the correct voltage, protects the battery, and preserves charging efficiency.

Safety considerations when choosing a charger

Beyond matching voltage, safety and build quality matter. Here are best practices to minimize risk and maximize charging reliability.

• Buy chargers from reputable brands that carry recognized safety certifications (UL, CE, FCC, etc.).


• Make sure the charger’s voltage and current (watts) rating meet or exceed your device’s needs; underpowered chargers can overheat and charge slowly.


• Use certified USB-C cables that can handle the power level your device requires; a high-widelity cable matters as much as the charger.


• Prefer chargers with built-in protections such as overvoltage, overcurrent, short-circuit, and thermal protection.


• Avoid daisy-chaining adapters or using damaged or inexpensive third-party accessories.

Adhering to these safety guidelines helps prevent damage to devices and reduces the risk of overheating or electrical faults during charging.

Summary

There is no one-size-fits-all voltage for chargers. The correct output is determined by your device’s specifications, typically ranging from 5V for basic charging to higher voltages (9V, 12V, 20V) through USB PD or PPS for fast charging, with laptops often requiring around 19V or 20V. Always verify the device’s requirements on the label or in the manual, use certified chargers and cables, and prefer devices that negotiate voltage safely through supported charging standards.

How many volts should my battery charger be putting out?

A healthy car battery charging voltage while the engine is running should be between 13.7 and 14.7 volts. The normal resting voltage for a fully charged 12-volt battery (engine off) is 12.6 volts or higher. If the resting voltage is below 12.4 volts, the battery is partially discharged and needs to be recharged to prevent sulfation, which can reduce its lifespan.
 
This video explains the voltage range of a car battery: 52sStudent LessonYouTube · Oct 5, 2023
Resting voltage (engine off)

• Fully charged: 12.612.612.6 volts or higher
• Partially charged: 12.412.412.4 volts
• Needs charging: Below 12.412.412.4 volts
• Fully discharged (or dead): 10.510.510.5 volts or lower 

Charging voltage (engine running)

• Normal range: 13.713.713.7 to 14.714.714.7 volts 
• Purpose: The alternator increases the voltage to charge the battery and power the vehicle's electrical system. 
• Low charging voltage: If the voltage remains at or below 12 volts while driving, the alternator may be malfunctioning. 

You can watch this video to see how the car battery charging works: 1mAdam MechanicYouTube · Dec 10, 2023

How many volts is a normal charger?

A normal charging voltage for a 12-volt car battery is typically 13.5 to 14.5 volts when the engine is running, as this indicates the alternator is properly charging the battery. When the engine is off, a fully charged battery should have a resting voltage of around 12.6 to 12.8 volts. 
This video explains the normal voltage range for a car battery: 1mOBD InsightsYouTube · Feb 13, 2025
When the engine is running

• Normal range: The voltage should be between 13.513.513.5 and 14.514.514.5 volts. Fluctuations are normal as the car's electrical system and accessories demand power. 
• Factors that can affect voltage:
  • Temperature: Charging voltage is higher in colder weather and lower in hot weather. 
  • Electrical load: Turning on accessories like headlights, air conditioning, or the rear defroster will cause the voltage to drop temporarily as the alternator works harder. 
  • Engine RPMs: Voltage may be higher at higher RPMs compared to idle. 
• What to watch for: Large, rapid voltage fluctuations can indicate a problem with the voltage regulator. 

You can watch this video to see how to check the car battery voltage with a multimeter: 1mRevive My RideYouTube · Mar 17, 2024
When the engine is off

• Fully charged: A fully charged battery will read approximately 12.612.612.6 to 12.812.812.8 volts. 
• Partially charged: A reading between 12.012.012.0 and 12.412.412.4 volts means the battery is partially charged and should be charged for its longevity. 
• Drained: A reading below 12.012.012.0 volts indicates a low state of charge, and readings below 10.510.510.5 volts mean the battery is effectively dead. 

This video explains the ideal voltage range for a car battery: 58sLegit RacecraftYouTube · Oct 26, 2012

Is 12.2 volts a dead battery?

No, 12.2 volts is not necessarily a dead battery, but it is low and indicates the battery is partially charged (around 50–60%) and may struggle to start your car. A fully charged battery should read about 12.6 volts or higher when the engine is off. You should recharge the battery to prevent damage and shorten its lifespan. 
You can watch this video to learn about checking your car battery's voltage: 39sTorqueCarsYouTube · Oct 31, 2023
Understanding your battery's voltage

• Fully charged: A healthy, fully charged battery will show a resting voltage of about 12.6 volts or higher. 
• Partially charged: A reading of 12.2 volts suggests the battery is around 50-60% charged and should be recharged. Running it at this low level for extended periods can reduce its lifespan. 
• Discharged or failing: A reading below 12.0 volts indicates a discharged or failing battery, and a reading of 10.5 volts is considered fully discharged. 

What to do next

• Recharge the battery: Drive your car for about 30 minutes, or use a battery charger, to bring the voltage back up. 
• Monitor the voltage: After charging, test the battery again. If the voltage is still low, or if it fails to hold a charge, the battery may need to be replaced. 

How many volts does a 12 volt trickle charger put out?

The ideal trickle charge voltage for a 12V lead-acid battery is between 13.5V and 13.8V. This "float" voltage is a constant, low-current charge that maintains the battery's charge without overcharging it. For a fully charged 12V battery, the resting voltage (without a charger) should be around 12.8V to 13.1V.
 
This video explains how to properly charge 12V lead acid batteries: 57sJTech LabsYouTube · Nov 9, 2024
For standby use (AGM or Gel) 

• Voltage: 13.5V13.5 cap V13.5𝑉 to 13.8V13.8 cap V13.8𝑉 
• Purpose: This is a maintenance charge to keep a battery topped off when it is not being cycled through deep discharges. 

This video shows how to trickle charge a car battery: 55smattcarlson12YouTube · Jan 10, 2024
For cyclic use (AGM)

• Voltage: 14.4V14.4 cap V14.4𝑉 to 14.9V14.9 cap V14.9𝑉 
• Purpose: This is a higher voltage needed to fully recharge a battery that has been discharged, like in an RV or boat. 
• Note: Once fully charged, the charger should switch to a maintenance/float charge of 13.5V13.5 cap V13.5𝑉 to 13.8V13.8 cap V13.8𝑉. 

Important considerations

• Battery Type: The voltage requirements can vary slightly depending on the specific battery type (e.g., AGM, Gel, Flooded) and its capacity. Always check the manufacturer's recommendations. 
• Temperature: For every 10∘C10 raised to the composed with power cap C10∘𝐶 (or about 18∘F18 raised to the composed with power cap F18∘𝐹) increase in temperature, the required charge voltage should be reduced by about 0.25V0.25 cap V0.25𝑉. 
• Multi-Stage Chargers: Smart chargers use multiple stages (bulk, absorption, float) to charge the battery efficiently and safely.