CaptD wrote:Thanks to all. I just found an article on the Clipper Creek site that says that level 2 charging is almost 5% more efficient, perhaps for the reasons that notfred mentions. That is probably why Kia recommends it.
Additional advantages to level 2 include the fact that, while level 1 heats the battery less, it heats it for a longer period of time. Depending on the climate, there are arguments both for and against level 1, given that fact.
Level 2 has a distinct advantage: it's more convenient/possible to give the car a cool-down time before you commence charging. A period of 90 minutes or so before you commence charging allows the cell temperatures to even out, and may give the BMS a more accurate sense of how each cell is faring and allow it to get a better idea of the health and state of charge of each cell. That may aid it in balancing and charging the battery pack. In hot weather, level 2 charging being faster would allow more time for the pack to cool down before the charging commences, if you set it up that way (I do). Similarly, in a heat wave you might wish to charge the car in the coolest period of the night, and level 2 could do the entire charge during that chunk of time, whereas level 1 may stray past it.
Overall I've gone from thinking level 1 was better, to now thinking level 2 is better overall. I suppose the ideal is to have both and use each strategically depending on circumstances.
Another important thing to remember is that fast charging is bad, but so is fast discharging (such as driving aggressively). Slower charging to 100% would generally be worse than faster charging to 80% or less. So charging isn't the be-all, end-all. But it's definitely an important piece of the puzzle.