RT01 Relay Tester or BT138 Battery Tester, Kit Options

Choose the tester that matches the check you need to make: RT01 for compatible automotive relays, BT138 for supported batteries, or the combined package for both tasks.

• ✅ Keep the two checks distinct - the RT01 and BT138 perform different testing roles.
• ✅ Choose a single tool or a kit - buy only the selected tester or both together.
• ✅ Read the indicated result - the RT01 uses status lights, while the BT138 provides a battery reading.

Select the Tester by the Component Being Checked

The RT01 is listed for suitable four- or five-pin automotive relays with coil resistance of at least 20 ohms. It requires an appropriate external vehicle-battery supply; it is not a self-powered tool that needs no connection.

The BT138 is a separate battery tester. Check its actual supported voltage and chemistry before use, and do not treat a voltage reading as a full capacity or health test. The selected package contains only the named tester or testers; batteries are not included.

Technical details

• Options: RT01, BT138 or RT01 + BT138.
• RT01 supply listed: 11-25 V external battery.
• RT01 relay formats: compatible four- and five-pin types.
• RT01 minimum coil resistance listed: 20 ohms.
• BT138: supported batteries only; verify unit markings.

Choose the tester or kit that matches your next electrical check.