I've not seen it, but it seem to be a fully silent device. According the past nomenclature, the the name of the charger is the product of V x A. The time to charge a certain battery will be accordingly.
I find it hard to believe those chargers are more than 2A and thus it would take 5hrs to make up half a charge. For $50 less you could get a Grin Satiator that will put out up to 8A and do so silently and intelligently for optimum battery life. Not micro size but small enough to carry along and overall the most advanced charger in the e bike market which the most advanced e bike deserves does it not? http://www.ebikes.ca/product-info/cycle-satiator.html