Why couldn't I jump-start my car with a 70-amp charger?

Yesterday, I left my lights on all day while at work in sub-freezing temps and the battery was dead, dead, dead when I got off work. I drive a 1997 Mazda Protege.





I had purchased a Schumacher "MityMite" Automotive Jump Starter/DC Power Source (PS-70A). It was fully charged. I attached the red clamp to the battery's positive pole and the black clamp to chassis ground.





Nothing. Nada. I let it sit there for a few minutes. Not even the slightest hint that a charge was present.





Lucky for me, someone else had jumper cables, so I jumped the car easily from a live car battery.





What went wrong? I followed the directions to the letter.|||Nothing went wrong. The average amps for a start up is 300 to 650 amps you didnt have enough power in the starter. Take it back and just be more careful. Even the biggest jumpstarters will not crank up a completely dead battery unless u can plug it into a wall outlet.|||not enough power in the booster.as another person said the portable boosters are meant for a low battery not a fully drained one. i carry one around in my truck as my alternator is weak. it works as long as my battery has some charge left in it.at startup is the hardest time on a battery. it drains the most power at that time.|||Take the mitymite back and get your money back. It is much safer to just cary jumper cables and let someone help you|||As the others have said..... most starters pull 300-600 amps when starting from the 12 volt battery. 70 amps will help a low battery, but not a dead one.|||Despite the name, those things aren't jump starters. They don't put out anywhere near enough current. They just give your battery a little bit of a charge if you leave them on for a while. If you didn't get any result at all, it was either dead or you didn't do something right.|||Easy, you might mite needs to be plugged in and fully charged before it will work. To find out on the MityMite, just briefly touch the two cables together to see if they spark. I bet they do not. Read the instructions and plug it in to the house or garage and fully charge it.





I know you said it was fully charged, but then touch the cables if the charger says it is fully charged. Possibility you had it fully charged and then somehow it discharged so when you tried to jump start the car it was down. Hard to say. If any thing else, if the unit says charges and the clamps do not spark, then you need to exchange. Also, does it have a switch for 6v too. That would make a difference.





LATE PS. If you did not have a good connection to the chasis, that would be a GOOD reason why it did not jump start. Next time, connect to the chassis and touch the red cable to the positive battery pole and you should SEE a slight spark, then you know you are good to go.





PS #2 If your battery was TOTALLY DEAD, your charger may have charged it up enough to get a boost from the other car. If your battery is totally dead it will take a couple of minutes for another car to charge it up, especially if you have an old battery.





So if the cables spark, then I would exchange it and get one with higher AMP since you live in a cold weather place to ENSURE a start dead battery or not.|||70 amps? Not near enough capacity.





The typical car starter motor usually draws several hundred amps of current-most of which is needed for just getting things moving. (Especially in cold temps). You're lucky your charger has overload protection. Notice how thick car battery cables and jumper cables are? They need to be that size to handle the currents involved with starter motors.|||Those things arent really meant to work on a dead dead dead battery.. just a low battery... The cold didnt help either...