I have a duracell emergency jump starter. If I take it home and plug it in, then, hook it up to my car battery for a few days, would the jump starter fully charge my car battery?
No. Here is a scenario. You have a good, but stone dead battery. You can attach a proper 10 amp charger to it and it won't even start to take a charge for about 30 minutes to an hour. Once it starts to take a charge, it can take up to 8 hours to fully charge. If your battery is not totally dead, it will take a charge immediately, but still takes hours to charge.
A booster pack like you have is designed to provide short bursts of power to assist a drained, but not totally dead battery. This is all assuming your battery is good. A bad battery can act very strangely depending on what is wrong with it. I recommend verifying whether or not the battery is dead or not, otherwise, you will have to keep on recharging the battery. Have your battery and charging system inspected, and if needed, replace your battery so you don't have to keep on worrying about this issue.
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