Which charger has a black and red wire?

Most commonly, 12V automotive battery chargers and trickle chargers use black and red wires—red for positive (+) and black for negative (−). Many DC chargers for hobby batteries (like RC LiPo/NiMH chargers), portable jump starters, and solar charge controllers also feature red/black leads, while USB power cables carry red/black internally but usually don’t expose them.

Why some chargers use red and black leads

In direct-current (DC) systems, red and black are widely used to indicate polarity: red for positive and black for negative/ground. Chargers designed to connect directly to battery terminals or DC rails commonly expose these leads to make proper polarity connections clear and safe.

Common chargers that feature red and black wires

The following examples represent the types of chargers and power devices where you will most often see red and black leads exposed for direct battery connection or DC output:

• 12V automotive battery chargers and maintainers (trickle chargers)
• Portable jump starters and booster packs
• RC battery chargers for LiPo, Li-ion, NiMH, and NiCd packs (often via alligator clips or banana leads)
• Solar charge controllers connecting to 12V/24V battery banks
• Marine/RV onboard chargers with ring terminals
• Bench DC power supplies with red/black binding posts or pigtails
• Motorcycle/ATV/SLA battery tenders with SAE two-pin connectors and red/black pigtails

In all these cases, the color coding helps ensure correct polarity when attaching to batteries or DC systems, reducing the risk of damage or hazards.

When you won’t see red/black externally

Some chargers provide DC output but hide the individual wires inside a molded cable or connector. In these cases, the color coding exists internally but isn’t visible to users.

The scenarios below explain where red/black may be present but not exposed:

• USB chargers and cables (red = +5V, black = ground, with white/green for data)
• Laptop power adapters with barrel or proprietary tips (polarity indicated by diagrams, not wire colors)
• Wireless charging pads and smart-device chargers (polarity managed inside the device)
• Power tool chargers with keyed, multi-pin connectors (internal wiring, color not user-facing)

Because the wiring is internal in these products, users typically rely on connector shape, labeling, or device specifications rather than wire color.

How to confirm polarity—and stay safe

Even with standard color conventions, it’s wise to verify polarity before connecting to a battery or sensitive electronics, especially if the wiring has been modified or the device is unlabeled.

Use the steps below to confirm and connect safely:

• Check the charger’s manual or label for polarity markings (+/−) and voltage ratings
• Use a multimeter to confirm positive and negative leads before attaching to equipment
• Match red to the battery’s positive terminal and black to the negative or chassis ground
• Look for keyed connectors (SAE, Anderson Powerpole) that enforce correct polarity
• Avoid reversing leads; incorrect polarity can damage electronics or cause sparks
• If wire colors are faded or nonstandard, rely on markings, continuity tests, or professional guidance

Following these checks reduces the risk of reverse polarity, short circuits, and potential damage to batteries or devices.

Regional and product variations

Color conventions are widespread but not legally universal. Some specialty equipment, legacy wiring, or aftermarket modifications may deviate from the red/black standard. Always defer to the device’s documentation and labeling. In automotive contexts, black is typically negative; in some older or specialty systems, however, ground could be differently colored—so verify when in doubt.

Bottom line

If you’re seeing exposed red and black leads, you’re likely dealing with a DC battery charger—most commonly an automotive 12V charger, trickle charger, battery maintainer, or hobby/bench power setup. Red is positive, black is negative, and correct polarity matters.

Summary

Chargers with black and red wires are typically DC battery chargers and related devices, such as 12V automotive chargers, maintainers, jump starters, RC battery chargers, solar charge controllers, and bench power supplies. Red denotes positive (+), black denotes negative (−). Many consumer chargers (USB, laptops) hide these wires internally, so polarity is indicated by connectors and labels instead of exposed colors. Always confirm polarity with documentation or a multimeter before connecting.

What is the black and red wire on a battery charger?

Connect the chargers positive cable (normally red) to the positive (+) battery terminal and the chargers negative cable (normally black) to the negative (-) battery terminal. If your charger allows it, decide whether you want to charge the battery slowly or quickly.

Which cable has red and black wires?

Cords with red and black wires are commonly used for low-voltage DC power, such as USB cables, speaker wires, and automotive wiring, where red typically indicates positive (+5V) and black indicates negative or ground. They are also found in some house wiring scenarios to represent a secondary hot wire and a primary hot wire for higher voltage circuits, though these wires carry different meanings depending on their function within the electrical system.
 
Common applications for red and black cords:

• USB cables: Opens in new tabThese often have red and black wires for power (5V positive and ground) and green and white wires for data transmission. 
• Low-voltage DC applications: Opens in new tabThis includes connecting single-color LED strip lights, powering hobby electronics, or in amateur radio and robotics. 
• Automotive and stereo systems: Opens in new tabRed and black wire pairs are excellent for identifying polarity in DC applications for car stereos or in-home theater setups. 
• House wiring: Opens in new tabIn some higher-voltage residential circuits, such as 240V outlets, a red wire can act as a secondary hot wire for a 240V circuit, while the black wire is the primary hot wire. 

How to tell the difference:

• Voltage and application: The context of the cord is the best indicator of its function. A small cord with red and black wires going to a device is likely low-voltage, while a thicker cable within a wall is part of the main household electrical system. 
• Polarity: For DC circuits, red is almost always positive and black is negative/ground. 
• Multimeter: If you are unsure, a multimeter can be used to safely test the wires for voltage and to determine their function within the circuit. 

What chargers have a red and black wire?

Chargers, particularly USB chargers, typically use a red wire for positive voltage (+5V) and a black wire for ground (GND) to supply power to a device. Other common chargers, such as those for car batteries, also follow this convention, with the red wire connecting to the positive terminal and the black wire to the negative terminal of the battery. 
USB Chargers

• Red wire: Carries the positive voltage (+5V) from the power source to the device. 
• Black wire: Serves as the ground connection, completing the electrical circuit and providing a return path for the current. 
• Data wires: In a standard USB cable, the green and white wires are for data transfer. 
• Power-only cables: Some USB cables are designed to be “power-only,” meaning they only have the red and black power wires connected and omit the data wires. 

Other Chargers (e.g., Car Battery Chargers) 

• Red wire: Connects to the positive (+) terminal of the battery or power source.
• Black wire: Connects to the negative (-) terminal of the battery.
• Important: When connecting these chargers, always connect the red (positive) cable first, and then the black (negative) cable to avoid damaging the battery or charger.

What charges have a black and red wire?

Typically, the color code is: Red: Positive power (Vbus) Black: Ground (GND)