Portable Jump Starters?

[DK327]

I bought the NEXPOW 2000A Peak Jump Starter from Amazon a couple of weeks ago when my 3rd gen had starting issues; it turned out I just had to clean the battery terminals, but kept the device anyway; haven't had to use it yet. It had close to 20K reviews and 4.5 stars, hoping it's accurate. I'll drain the battery to below 12V and test it when it gets warmer out and report back.