Instruct: Classify Amazon reviews into positive or negative sentiment
Query: as a back-up it's worth the price-NOT A SUBSTITUTE FOR JUMPER CABLES THOUGH

IN AN EMERGENCY IT'S WORTH HAVING (DESPITE ALL THE NEGATIVE REVIEWS). IT TAKES AT LEAST A HALF AN HOUR TO WORK. I WASN'T EXPECTING IT TO WORK AT ALL AND IF YOU LEAVE YOUR HEADLIGHTS ON TOO LONG YOUR BATTERY MIGHT BE TOO DRAINED FOR THIS TO WORK, BUT FOR LIGHT CHARGING THIS MIGHT JUST DO THE TRICK. MY BATTERY WAS AT ABOUT 11 VOLTS BECAUSE I WAS USING THE AUX. POWER LONGER THAN I SHOULD HAVE WITH THE ENGINE OFF (MY BATTERY IS KIND OF WEAK ANYWAY). I DIDN'T HAVE TO CALL AAA OR GET SOMEONE TO GIVE ME A JUMP START (I DID HAVE TO WAIT ABOUT A HALF AN HOUR FOR THE UNIT TO WORK). THIS UNIT IS NO SUBSTITUTE FOR JUMPER CABLES OR TRIPLE A, BUT IF YOU HAVE THE TIME AND YOUR BATTERY ISN'T TOO DRAINED, THIS UNIT CAN HELP. FOR THE PRICE ITS WORTH CARRYING AROUND.