The cable may be faulty, but is probably undersized (wires/veins too thin), causing a voltage drop in the wires due to the (high) current. Even if it outputs 6.2V, what arrives at the PI, is too low. Have a look in the PI docs when the PI flags it as "undervoltage".
Btw, 6.2V is too high and may fry your PI. I believe the max ranges for proper/safe operation are between 4.75 and 5.25 Volt
Btw, 6.2V is too high and may fry your PI. I believe the max ranges for proper/safe operation are between 4.75 and 5.25 Volt
