Charging, Part One

Speaking of roadside stations… Before I can describe charging my motorcycle, I have to describe charging in general.  How does one juice up something big and mobile?

I’ll point out immediately that RV parks and marinas solved this problem decades ago (plus the owners of electric forklifts, more recently).  If you want to run something bigger than a lamp or hair dryer, you might want some plug bigger than that.  And as your plug (and its current) gets bigger, you might want voltages higher than 120V.  Fortunately, a surprising number of people rarely need bigger than that.

The “normal” plug is officially NEMA 5-15,  a standard from the National Electrical Manufacturers’s Association.  It’s rated for 110-125 volts, 15 amps in North America.  This, then, is defined as “Level 1” charging.  It has a ground pin; if you’re plugging into a GFCI outlet (or “receptacle,” officially) you can plug it in outside or in the rain and not shock yourself.  Some quick math shows that a reasonable 10-amp draw at 120V is 1.2 kilowatts.

Next up from NEMA 5-15 are the 120V plugs for RVs, and 240V plugs for electric dryers, ranges, and RVs.  For years, homebuilders charged their vehicles with dryer plugs, since dryers are often in or near the garage or driveway.  Thus, you may still find kits and adapters to NEMA 10-30 (dryers before 1996), 14-30 (after 1996), 14-50 (electric ranges), and the RV standards (often L6-20, sometimes others).  Even at the same 120V, the higher current can charge batteries faster.

Still, these were not meant for ordinary motorists at high-traffic stations.  “Level 2” plugs (officially, SAE J1772, from the Society of Automotive Engineers) are 240V, and commonly carry 20-30 amps and up, all the way to 80 amps.  The big difference is that J1772 is a smart connector.  The wall side is not energized, until it communicates with the vehicle side.  The vehicle can request a certain amperage, and only upon a successful link (a “handshake” in the electronics world) will the wall side begin to carry current.  This lets you hook up safely in the rain, or even in drizzle, road spray, heavy fog, etc.  Communications also include a “don’t drive off” lockout for the engine computer, and an “I’m full” command to the wall.  This lets a network-connected station send you a text or e-mail when you’re ready, or even a message if you’ve been unplugged by someone.  You can also tally your usage with meter readings, if you’re into that.

On a more basic level, the J1772 plug is physically durable.  It’s been designed to last for thousands of plug/unplug cycles, you can run it over, etc.  At 20-30 amps, you’ll charge at 3.3 to 7 kilowatts- much faster than household 120V.  The downside is that J1772 charge points- even for homeowners- cost a minimum of several hundred dollars.  Fully weatherized, vandal-resistant stations are thousands of dollars at present, before internet fees.

Public Level 2 station (J1772). Many ChargePoint units also have a Level 1, under door marked “1.”

J1772 has the backing of SAE, DOE, automakers, etc. and is thus the most common station… on public roads.  There are many times more NEMA 5-15 receptacles that were meant for yard work, maintenance crews and contractors, signs and displays, holiday lights, etc.  Other electric motorists have noted that stores and restaurants will usually let you charge off their 5-15s if you’re a customer, and ask nicely.  Particularly if you explain just how little an hour of electricity costs, through a 5-15.  One EV driver I know has even knocked on doors in residential neighborhoods.  He’s found that he only needs to try a few houses before someone answers, with a yes.

There’s also the question of recharge time.  Do you even need a Level 2 in your driveway?  A large fraction of personal EV owners- maybe even a majority- are saying no.  Home recharging takes place overnight; given eight to twelve hours, Level 1 is plenty for day-to-day.  Average people drive 25-50 miles in an average day, and thus, many modern EVs aren’t even close to empty.  (If you actually discharge your battery that far on most days, you planned poorly.)  If you’re an average person, and you check your plan carefully, you can come home to a regular, dumb, cheap 120V outlet.  You can still upgrade later, even if it’s just to your existing dryer socket.

Faster charging is more important on the road, when you’re trying to fit it into a store visit, professional appointment, meal time, rest stop, etc.  I’ll fit in even faster Level 3 charging stations in the next Part.

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14 thoughts on “Charging, Part One

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