02 May 2010

500 miles from home

Our first really long trip taken by charging the electric car at "RV parks" was not always fun. But it can be done. We drove from New Jersey to North Carolina. We did not quite make it in two days as planned, but almost.

The short story is that many campgrounds or Recreational Vehicle (RV) Parks that have 50 amp receptacles do not maintain them well. The screws on the connectors, circuit breakers, and buss bars should be tightened periodically. Breakers that have tripped many times tend to get weak, and trip at lower than rated current. These circuit breakers should be replaced.

Without this maintenance, the circuits can run hot and will not sustain the 100% current rating for 3 hours, which the specifications require. (For more than 3 hours, load must be reduced to 80% of rating. Fortunately, the Mini E draws 48 amps for about 2.5 hours and then current draw decreases for the last 30 minutes of charging.)

We had varying trouble with circuit breakers tripping at almost half of the campgrounds we visited. At one campground, we tried over 6 camp sites before finding a power outlet that would charge the car for more than 10 minutes or so. On the return trip, we gave up completely at one campground and left with only 50% charge because no circuits would stay on for long.

For this and other reasons, our travels took a bit longer than planned. Of course the best course of action when a 50 amp circuit will not support 50 amps is to reduce charging current to 32 amps, and get where you are going later than planned.

Disclaimer: The US National Electrical Code does not approve of operating Electric Vehicle Service Equipment rated over 1500 watts (which is the size of the Mini E slow charger) unless it is permanently connected to a circuit that is rated at 20% higher amperage than what the car draws. The fact that RVs are allowed to connected through a NEMA 14-50 connector at 240 volts 50 amps, while an electric car is not allowed to do so, might be thought of as a Grandfather clause. The NEMA 14-50 connector is old and not particularly safe for the general public to use on a daily basis. It is not so problematic when hidden behind your kitchen stove for 10 years at a time.

Anyone employing such unapproved uses should be well trained and carefully monitor the connections while charging a car. Really, it should not be done at all. Hopefully we will have purpose designed charging infrastructure more widely installed soon.

I have heard that Tesla supports charging through a NEMA 14-50 plug. If that is true, I am curious how they do that with the electrical code as it stands today. And Tesla has quite a few more options for setting the charging current. It would be nice to be able to reduce current to 40 amps in the Mini E for instance.

The bottom line on our trip is that traveling long distances by electric car is possible now. It takes a lot of planning, and the first trip might be troublesome but once you learn which campgrounds to avoid, it can be very pleasant albeit slower than piston powered travel. We enjoyed driving a couple hours and then stopping for a couple hours to hike, eat, nap, or whatever before heading out again. That is, when we were at well maintained camp grounds.

Oh, and bring bottled water. Don't trust the well water at campgrounds.

Yeah, and as other bloggers have mentioned, the only 240 volt receptacles at campgrounds in the US are those that are nominally rated 50 amps. The 30 amp receptacles are 120 volt "NEMA TT-30" and cannot be used with the Clipper Creek safety box. 20 amp receptacles are always the standard home style (NEMA 5-20) plugs. We did use 20 amp outlets at motels with the slow charger. More and more motels seem to know where their outdoor outlets are and are OK with them being used.


  1. Very interesting Post Jim. What did the camp grounds charge you to charge up, and how many stops did you make? No sure I'd be as comfortable as you with the camp ground plugs but maybe after watching someone else do it a few times, and if I knew others had used a campground for this.

  2. Robert

    Most camp ground prices were about $10, some less and a few required full price of an over night stay, usually $35 or so. Those were often the ones that had the worst maintenance, and the breaker would trip in less than 30 minutes.

    I'll do another post about it soon.