BTW, I bought the Zencar unit with a 5-15 plug, and have been using it for a few days. It's worked well, so far, and definitely took hours - about 6 - out of the charge time from 0-100%. It and the cord do get a little warm - 45*C(ommie), which translates to 113* 'Merican.
That doesn't seem bad, in a garage that's 70-80*.
Thanks for the suggestion!!
Mark