I have never tried any of those, as I have ready access to professional-grade heavy duty battery chargers and jumper cables

Keep in mind that the cigarette lighter circuit is limited by its fuse to between 15 to 30 amps max. That's about 10% or less of what your typical starter motor wants to perform. No way can it be used as a jumpstart device. Its something that will charge a battery at a rate of charge usually classed as "slow" by most battery chargers.
I don't see the point unless for a vehicle that sits for long periods of time between usages. A set of jumper cables that can be carried in the vehicle is a more practical solution for emergencies.
This is the kind of product that Black and Decker usually makes well, if you're gonna buy one its prolly a gud un.
culero (done spent his $0.02

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