8-9 hrs is generally our top end as well but this time we will do a 20 plus hr push to get out of the frozen tundra and ice storm area in one day to beat another storm that appears to be trailing behind if the weather holds in the next 10 days. If it was the Smart it would be no problem but Jeep I am not sure so will start when stopping for a break. If worse comes to worse I can start the generator in moho and put the battery charger on for awhile and take a rest. I believe if I lose the battery power I lose my even brake.