KONNWEI KW371 Battery & Relay Tester — 6V/12V/24V, 4/5‑Pin Relay, CCA/Ah Readouts

The KONNWEI KW371 is a portable 2-in-1 automotive diagnostic tool that tests 6V/12V/24V batteries and verifies 4-pin/5-pin relays to quickly identify battery, starter, alternator, or relay faults.

The KW371 combines broad battery compatibility with relay diagnostics and cranking/charging analysis in one handheld meter. It supports Lead-Acid, AGM, Gel, EFB, and Lithium chemistries across 6V, 12V, and 24V systems and reads CCA, Ah, and multiple international standards. Its waveform display and clear result wording make it useful for professional garages, fleet operators, and experienced DIYers who need fast, reliable on-vehicle diagnostics without removing components.

How does the KW371 determine if a battery needs replacing?

The device performs a battery health test that reports state of health (SOH), state of charge (SOC), internal resistance, and voltage. It compares measured results to standards (CCA, EN, DIN, JIS, etc.) and offers a clear pass/fail suggestion—Good Battery, Replace, Bad Cell, or Charge Retest.

• Measures 10–2000 CCA and 5–220 Ah ranges
• Supports multiple battery chemistries and international standards
• Displays internal resistance and SOH percentage for informed decisions
• Powered directly from the tested battery—no internal batteries required

What tests reveal starter or alternator problems?

Use the KW371’s cranking and charging tests to isolate starting and charging system faults. The cranking test records minimum and maximum voltage and cranking duration in milliseconds, while the charging test checks unloaded and loaded voltages plus ripple, helping distinguish between a weak battery, failing starter, or an alternator that’s not regulating properly.

• Cranking test: minimum/maximum voltage and cranking time
• Charging test: loaded/unloaded voltage, ripple detection
• Graphical waveform shows real-time voltage behavior under load
• Quickly indicates whether issues are battery-, starter-, or alternator-related

How does the relay tester work and why is it useful?

The integrated relay tester checks 4-pin and 5-pin automotive relays to detect coil faults, sticking or worn contacts, and incorrect switching without removing the relay from the vehicle. It saves time by identifying faulty relays in-place—useful when troubleshooting lighting, fuel systems, cooling fans, or accessory circuits.

• Tests both 4-pin and 5-pin relays for coil continuity and contact operation
• Diagnoses relay faults without disassembling the fuse box
• Reduces diagnostic time for intermittent electrical faults
• Ideal for mechanics, fleet techs, and advanced DIY troubleshooting

How easy and safe is it to use in the field?

The KW371 was built for practical, on-vehicle use: rugged alligator clips connect directly to the battery, eliminating the need for internal batteries. The interface provides multilingual menus, polarity reverse protection, and a graphical display so results are easy to read in a busy workshop or roadside scenario.

• Multilingual menu including English, Spanish, French, and more
• Polarity reverse protection protects the unit and user from incorrect hookups
• USB connection for Windows PC updates and printable reports
• Durable clips and casing for garage or field use

Who is this for? The KONNWEI KW371 suits professional mechanics, fleet and RV/boat managers, and knowledgeable DIYers who need a single handheld tool to diagnose batteries, starters, alternators, and relays across 6V/12V/24V systems. It’s especially valuable where quick, reliable on-vehicle testing and international battery standard support are important—repair shops, roadside assistance, and maintenance fleets will find it saves diagnostic time and reduces parts guessing.