Portable Level 1 EV Chargers Are an Overlooked Concern

The charging level delivered by the 120-volt Level 1 charging cables included with most EVs can vary unexpectedly. In the U.S., we have 120-volt household power rather than the 240-volt power that is standard in most other countries. This works fine for our devices and appliances other than the clothes dryer, which needs more power than a typical 12-15-amp 120-volt circuit can deliver, so it is rarely an issue.

But when an EV driver needs to be able to recharge in an area with no charging stations, an overnight top-up with the (usually) included 120-v Level 1 charging cable can add the range needed to get to a DC fast charger. This was my expectation during a recent 150-mile trip to my mom’s house in the Kia EV9.

A round trip without a recharge would be right at the vehicle’s theoretical range limit, so I planned to have the EV9 plugged in with its included Level 1 charger for a day and a half during the visit. A solid 24 hours plugged into a wall outlet in my mom’s garage should ensure a return trip with no trouble.


After all, with 12-amp service, a 120-v circuit can deliver 1.4 kilowatts of charging power (12×120/1000). That 1.4 kilowatts for 24 hours equals 34 kWh of power delivered to the battery. That represents about one-third of the Kia’s 99.8 kWh battery pack’s capacity, or roughly 100 miles of range delivered.

During my drive, the EV9 averaged 2.9 miles per kWh, so the resulting 98.6 miles of range corresponds with that estimate. It should have been good for the return trip.

It was not. By morning, when I checked on the charging status, the vehicle appeared to be charging but didn’t seem to have increased the battery’s state of charge or the forecast available range, which had been at about 85 miles remaining on arrival.

I checked, and Kia product planners responded that the included charger should add about a mile of driving range every three hours. I looked at the specs and saw that Kia’s charger is only rated at 0.7 kW, which is half the normal level. After 12 hours, that should have equated to 8.4 kW of juice added to the battery, good for 24 miles.

But instead, the change was so small, at first I thought it hadn’t charged at all. It was only a few miles of added range, which was exactly what the product planners had said: one mile per three hours of charging time. So it added about 4 miles and the EV9 forecast 89 miles of range versus the 85 miles when charging started the day before. That’s more like 0.1 kW of charging speed or the power of a bright 100-watt incandescent light bulb.

This is the amount of power delivered by a 1-square-foot solar panel in noonday sunlight. The reason solar cells aren’t commonly installed on EVs is that this power return is so paltry that it is only suitable for aiding with some of the ancillary loads like infotainment and lighting, not for propulsion.

“That’s nuts, why even bother to include a cable if it’s that slow?” asked Sam Abuelsamid, principal analyst, transportation and mobility at Guidehouse Insights. Indeed, why bother?

Alarmed by the slow charging, I unplugged the cable from the EV9 and plugged it back in, just to reset the charge session. It showed the same plodding rate of charge, though the dashboard reported a 0.7 kW charge rate.

The issue here seems twofold. First, the rated power of the included charging cable is insufficient. Most carmakers I surveyed said theirs deliver 1.4 kW. That makes sense because that’s all the power available from 12-amp, 120-volt service. If you’ve got 15-amp service, then you’ll benefit from a small boost if you buy an aftermarket charging cable like the Lectron Portable Level 1 15A EV Charger, which that company says delivers 1.65 kW of the theoretical maximum 1.8 kW available on the circuit.

General Motors and Toyota drivers have another option. Because most countries use 240-volt power, their charging cables, like the chargers for most personal electronics, can work with either voltage. If you go someplace where there’s 240-v power available, such as a garage with a plug for a heater, compressor, or welder, then the included charging cables for GM and Toyota vehicles can swap the 120-v plug end for a 240-v plug that connects to those outlets to get 7.6 kW of power to the battery.

The Kia’s Level 1 charger was still wrapped up in plastic, indicating that nobody had yet used it. That is probably typical for EV drivers, considering how slow even good Level 1 charging is.

But the nearly total uselessness of the EV9’s included charger, which was far slower than its own very low power rating. This experience suggests that drivers might well dig that charger out and give it a try to see what they can expect in case they ever need it.

The utility of charging from standard wall outlets when you’re parked somewhere that the car will be for an extended period makes sense, because very little if any additional infrastructure is needed and it can provide a useful amount of driving range when it is time to go. This was the thesis of a column by Car and Driver’s Ezra Dyer, who had the experience of leaving an EV parked at a cruise ship port for a week. Even the Kia EV9’s charger could add a beneficial amount of driving range in a week.

Many Lectron charging cable customers indicate in their online reviews that they are Kia EV6 drivers, because that car doesn’t come with a charging cable at all. It turns out, that is effectively also the case for the EV9, because its cable doesn’t do much. EV drivers, give your Level 1 charge cables a try.