I've been reading this thread with great interest because I was very close to buying the PHEV, but the salesman said it should not be charged on a 120V circuit and the service dept confirmed it.
I didn't believe them so came to this forum for information, but it doesn't look like there is a concrete answer from KIA.
I tried calling KIA but got nowhere, so still not sure about why the manual says to use the 120V charger as a backup charger only.
Another dealership that doesn't understand what they're selling. Sigh...
There's absolutely nothing wrong with charging on 110-120VAC. If the battery is completely discharged (actually the car switches to hybrid mode at about 20% SoC), it takes about 5 1/2 hours to charge. using 220VAC, it's more like 2 hours and 15 minutes. Since the PHEV only has a 16 amp charger on board, that's as fast as it can go, regardless of the power capability of the EVSE (charger) you connect to. If you rarely exceed the EV range, and charge overnight, there's no real need to install a 220v EVSE. But if you'd like to top it off between trips, and drive over 30 miles a day, having the faster charging allows much more EV only driving. I typically seem to go between 40-50 miles a day often, but because I always plug it in at every opportunity, I rarely need the gas engine.
I Think Kia uses the phrase backup or trickle charger because they feel the owner will be happier the more they drive under EV power, and by implying a 220v circuit should be considered "normal", they won't have to contend with owners that aren't happy about how often the ICE is running.
Also, think about it. If charging via 110v was not recommended, why on earth would they include a 110v "charger" with the car? I really wish dealers would educate themselves better.