What if JS isn't detecting my car's battery?
If JS is not detecting the battery it is possible the voltage is too low to detect. JS is designed to jump start 13-volts lead-acid batteries down to 0-volt.But if your battery is below 2-volts, the LED of the smart clamp 【Only for the JS-Mini & JS-4】will be blank .This is an indication that JS can not detect a battery. If you need to jump start a battery below 2-volts there is a Manual Override feature, which allows you to force "On" the jump start function.