Any port in a storm

A month ago, an unexpected road closure left me driving into a rest stop with "0 miles" indicated. Explaining the problem to a maintenance man, he gave me permission to put on enough charge to reach a nearby SuperCharger. But I had to park on the grass which was not optimal. So this is how to prepare to use your 110-120 VAC, EV portable charger in an emergency.

First carry a 15 A rated, long extension cord. For example:

Or better yet:

The next problem is finding an exterior outlet:

• Tennesse Rest Stop I65 - two were found but only one was practical:
• Alabama had rebuilt the rest stop so this was the best:

So walk around the property and look where the maintenance vehicles are parked. Always ask before plugging in and be courteous (tips are nice, order hot pizza, can of mixed nuts.)

The maximum current from a typical NEMA 5-15 outlet should only be 12 A. But sometimes, you need to derate the charge rate because of other loads on that circuit. Start at 8 A and see what voltage the car reports. Then up it to 12 A and see the voltage drop. If large, go back to 8 A. My Model 3, 250 W/mi, will typically see:

• 8A - ~880 to 960 W/hr, about 3-4 miles charge per hour
• 12A - ~1,320 to 1,440 W/hr, about 5 miles charge per hour

Turn off everything you can so all the charge goes into the battery. Once you have enough with a little reserve, thank them and slowly drive to the nearest charger.

Always try to have enough reserve, typically 40 mi, to the next fast DC charger. Then drive checking the indicated range and miles to charger:

• +40 miles - keep up with traffic
• ~30 miles - become the slow poke, follow moving vans or slowest semi-trailer trucks
• ~20 miles - become the *sshole and use the minimum speed with flashing emergency lights
• ~10 miles - find a safe place for the tow truck to pick you up which led to my adventure

Bob Wilson

 

If I might expand:

Most of North America has two ways to deliver 110/120 power:

• Split phase, 120/240 VAC:
• Three phase typically commercial, 110 VAC: There is another 3-phase wiring but regardless, the same effect.

If you find two NEMA 5-15 (or NEMA 5-20) plugs near each other, they may be the legs of a split phase or 3 phase circuit, 210-240 VAC. With two extension cords and a 2-to-1 adapter, one could double the voltage and kWh rate. But the risk is each leg will have a separate, circuit breaker and the 8-12 A limit will still apply. And you're at someone else's business or house?

IMHO, doubling the charging kW rate does not justify two extension cords and the 2-to-1 adapter on the road. More parts, weight, and risks. It is OK if it is your home, apartment parking, or business but we're getting close to the range of "the smoke escapes" or "Who tripped my dam circuit breaker!!!"

Bob Wilson