Description
Topdon CT100 Digital Circuit Tester
3.3–65V DC voltage measurement, 0.1V resolution and a 5–30V / 1.2A load test in one tool. Quickly find fuse, connector and wiring faults on 12V, 24V and 36V vehicle systems.
What Is the Topdon CT100?
The Topdon CT100 is a professional digital automotive circuit tester built to diagnose vehicle electrical faults. When the probe touches a circuit, the backlit display shows the measured voltage instantly.
A basic test light only tells you whether power is present. The CT100 measures voltage with 0.1V resolution, indicates polarity by colour and runs a load test to check whether the circuit holds voltage under current — revealing aging batteries, weak connections and voltage drops that a test light cannot show.
With a 3.3–65V range, the same tool works on cars, trucks and RVs (12V, 24V and 36V systems).
Key Features
Professional Load Test
DC 5–30V, 1.2A max. Hold the button for 5 seconds to check battery and circuit load capacity and quickly identify aging batteries, weak connections and voltage drops.
Precision Voltage Testing
DC 3.3–65V range with 0.1V resolution. ±0.1V accuracy from 3.3–60V, ±0.2V from 60–65V.
Polarity Indication
Red (positive) or green (negative) backlight and on-screen ± indicators activate as soon as the probe touches a circuit, helping prevent reverse connections.
Battery-Free, Built-In Protection
No batteries to replace or maintain. Overvoltage alerts, overheating warnings and component status monitoring are built in.
Extra-Long Test Lead
12.5 ft test cable reaches hard-to-access areas without repositioning. Universal 4mm banana plugs for interchangeable probes and clips.
Wide Vehicle Compatibility
Supports 12V, 24V and 36V systems: cars, trucks and RVs with a single tester.
Typical Uses
- Checking fuses
- Verifying connector voltage
- Testing circuit integrity
- Tracing wiring issues
- Diagnosing starting-related electrical faults
- Detecting voltage drop under load on batteries and circuits
Specifications
| Brand / Model | Topdon CT100 |
| Voltage Measurement Range | DC 3.3 V – 65 V |
| Load Test | DC 5 V – 30 V (Max. 1.2 A) |
| Measurement Accuracy | 3.3–60 V: ±0.1 V · 60–65 V: ±0.2 V |
| Measurement Resolution | 0.1 V |
| Vehicle Systems | 12 V, 24 V, 36 V |
| Test Lead | 12.5 ft |
| Connection | 4 mm banana plug (interchangeable probe and clip) |
| Power | Battery-free |
| Working Temperature | -10 °C to 50 °C (14 °F to 122 °F) |
| Storage Temperature | -20 °C to 70 °C (-4 °F to 158 °F) |
Package Contents
- CT100 tester
- 2mm probe
- Alligator clip
- Adapter
- Carrying bag
- Quick user guide
Why Nitro Bilişim?
Topdon Distributor in Turkey
Genuine Topdon products backed by the official distributor.
Technical Support
Hands-on help with usage and electrical fault finding.
Frequently Asked Questions
How is the Topdon CT100 different from a basic test light?
A test light only shows whether power is present. The CT100 digitally measures voltage with 0.1V resolution, shows polarity with red/green light and runs a load test of up to 1.2A to reveal voltage drops.
Can it be used on 24V trucks?
Yes. The CT100 measures DC 3.3–65V and supports 12V, 24V and 36V vehicle systems, so it works on cars, trucks and RVs.
How do I run a load test?
Hold the button for 5 seconds. The tester applies a load of up to 1.2A in the DC 5–30V range, exposing aging batteries, weak connections or voltage drops.
Does it need batteries?
No, the CT100 is battery-free. There is nothing to replace or maintain, and overvoltage and overheating warnings are built in.
The Topdon CT100 goes beyond “is there power?” and shows voltage, polarity and behaviour under load in one step. Browse Topdon testers and test equipment, or contact us with any questions.
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