The Vanguard Auto-Ohm 10 is a 10-ampere battery powered micro-ohmmeter designed for low-resistance-measuring applications such as the measurement of resistance in circuit breaker contacts, bushing contact joints, and welding joints. The unit is powered by four 3400mAh, 3.7Vdc Li-Ion rechargeable batteries. With these high capacity batteries, up to 2,900 tests per charge (10A/2 second duration) can be performed in the field.