ElectroClassic EV
Classic Cars Reborn into the Electric Future

Baby’s First Charge

Most people generally assume an EV charging station is a battery charger, when in reality, the charger is located inside the car. The charging station at your local mall simply delivers 240 volts to your car through a standard J1772 plug, and the battery charger in your EV does the hard work. It’s great for filling up while you enjoy a movie at the multiplex, but how do you charge your EV at home?

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One solution is a residential EVSE (electric vehicle service equipment) charging station that includes a J-plug, and can actually meter and collect data on your energy usage. Shown above is the Blink wall-mount home charging station, which is internet capable and manages your charging to take advantage of off-peak rates.

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The low rent solution is plugging directly into your home power outlets, feeding either 120 or 240 AC volts to your EV through a J1772 plug with the help of a couple simple pigtail adapters. I purchased my J-plug from TucsonEV for the sole purpose of charging at home, or opportunity charging while parked somewhere with access to 110 or 240 VAC outlets. The J-plug includes a 20 foot cable with a raw end that can be fitted to any connector. I chose an L6-30 male locking plug that will mate to a couple different pigtails.

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The male side of this pigtail adapter was fitted with a heavy duty 120 volt 15 amp plug that is compatible with any standard wall socket. I was careful to make sure the hot and neutral wire paths were consistent from the charger across the J1772 receptacle, through the pigtail, and all the way down to the prongs on the 120 volt plug. This attention to detail is not critical, since the Elcon PFC2500 charger isn’t polarity sensitive to a 110 VAC source, but I went the extra mile for good form.

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The most common 240 VAC outlet in a house usually powers a clothes dryer, so I built another pigtail with a dryer plug so I can charge at a higher voltage when the opportunity strikes. The center wire must be connected to ground, while the other two wires are both hot and interchangable. In the future, I can add more 240 volt pigtails as needed, including a welding plug and a 4-prong dryer plug.

.Household outlets are usually always live, so there is a hazard of electrical arcing across the air-gap between the J-plug and the charging port when connecting up. A charging station deals with this by withholding power until the J1772 plug is fully connected, and senses the pilot signal. I’ll do this manually by adding a switchbox in the charging cable to keep the power off until the J-plug is fully seated. I purchased the above 277 volt/30 amp-rated switch at a local electrical wholesaler, along with the box, weather resistant lid, and compression collars for the cable. The switch is double-pole/single-throw, which basically means it operates two switches with one lever. This is required with 240 volts because two wires are hot, and both sides of the electrical loop need to be switched in tandem. This switch will also easily handle 120 volts, as long as the polarity of the hot, neutral, and ground are maintained across the terminals.

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All that remains is to plug the car in. I don’t have a 240 volt outdoor charging outlet yet, so I ran an extension cord into my laundry room, and plugged in using the adapter. This will be the first time the charger has been powered-up, and the very first charge the battery pack will know aside from the initial factory boot up. I inserted the J-plug into the charging receptacle under the front license plate, flipped the switch on the junction box, and held my breath.

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There was a tense and squeamish moment waiting for the escape of magic smoke, but no such thing happened. The cooling fan of the Elcon charger spun up nearly silently, and the signal light at the lower right issued six red blips, reflecting the charging curve it’s programmed to use on my battery pack. After monitoring the process for seven hours, the extension cord became concerningly hot, especially at the wall outlet. So I canceled the operation short of a full charge, and ordered some better power cable from McMaster-Carr.

I picked out 30 feet of black rubber insulated 12 gauge 25 amp copper stranded cable, and it arrived the next afternoon. You gotta love McMaster-Carr. I installed an L6-30 locking connector on each end, and used the pigtail to plug into the same wall outlet. After an hour of charging, the cable, connectors, and outlet were still cool and happy.

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Four hours later, the MiniBMS modules were starting to shunt current away one-by-one, signaling that their respective battery cells had reached the ceiling voltage. When shunting, the moduleĀ prevents the cell from taking on any more electrons, and a red LED illuminates. When all modules are finally in shunt mode, the BMS control board shuts the charger down.

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But an unexpected BMS alarm event triggered after only 7 of the 36 modules had started shunting. More than likely, the control board detected a battery cell that had just tipped beyond the ceiling level. The same signal LED on the Elcon can also tell me if the charger itself is throwing an error. Counting the green and red blips allows cross-referencing to an error table provided in the documentation. I will call CleanPowerAuto to determine why the MiniBMS is tripping the alarm. More to come.

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3 Responses to “Baby’s First Charge”

  1. It’s been a while since your last post! Keep it up!

  2. It would be interesting to hear CleanPowerAuto’s response, but it was my understanding that the shunt resistors slow down the charge to the first cells to reach 3.5 volts, and that it takes several charge cycles to get the cells into balance. I’m planning on using the same system on my batteries.


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