North American vs EU portable EVSE

Hi,

My understanding is Germany and the UK use 230 VAC which makes me wonder how they made a USA version that uses 120 VAC. But I don't want to take mine apart to see what they did.

Any suggestions on how I might find one to analyze?

If our BMW EVSE can run on 240 VAC it would double the rate of charge at home, just under 3 kWh. But I'm not interested in letting the smoke out of the micro controller.

I may have found a solution: http://www.aprs.org/charging-DIY.html

Thanks,
Bob Wilson

Some have reported that BMW and other EV manufacturers buy their included 120V EVSE's from local EVSE manufacturers and don't manufacturer EVSE's themselves. As a result, the EVSE included with the i3 in Europe is different from that included with North American i3's, neither of which is dual-voltage (i.e., 120V and 208-240V). EVSE Upgrade modifies Panasonic 120V EVSE's included with the Nissan Leaf and Mitsubishi i-MiEV, for example, to be dual-voltage EVSE's. For some reason, EVSE Upgrade doesn't modify i3 OUC's. We had our i-MiEV EVSE so modified and it would have worked fine with our i3.

I probably should have included our i3's OUC with our i-MiEV when we traded it in and kept our dual-voltage i-MiEV EVSE for use with our i3, but I was concerned that if our i3 had any charging problem and BMW learned that we were using a modified EVSE for charging, BMW might deny warranty service.

It might be possible to modify the i3's OUC to make it dual-voltage, but doing so would invalidate its warranty obviously. Since I want to be able to charge a little faster than our i3 EVSE's 12A maximum, I bought a 40A max. JuiceBox which has a voltage-sensing power supply that can function at 120V with an appropriate plug adapter. It would be easy to slide our JuiceBox out of its slide-in wall mount and put it in the frunk for use as a portable EVSE although it is certainly more bulky than the OUC.

Indeed, we followed the same approach with a JuiceBox Pro 40 at home. But soon I realized this was a poor use of resources. I really needed the L2 for fast, higher power charging when time is short, such as when shopping.

Bob Bruninga's paper "Overlooking L1 Charging At-Work in the Rush for Public Charging Speed": http://www.aprs.org/Energy/Charging/IEEEpaper.pdf. He makes a credible argument for L1 charging at work. He points out there is an EV triangle: (1) to work, long commute, (2) shopping errands, and (3) home. The long time at home and at work makes L1 charging ideal. At shopping and entertainment areas, L2 charging makes sense. I would complement his paper by pointing out what the absence of at work charging does.

Instead of staying at work through the lunch hour, it makes sense to seek nearby L2 chargers, especially free, for the lunch hour. Instead of taking a sack or snack lunch, the employee leaves their office, phone, and work resources to grab a quick charge and too often over-sized lunches. But the employer loses that labor which typically costs at least 100 times more than the electrical cost.

At ~$50k per year including benefits, an hour at work would cost the employer about $25. But the electricity for a typical 10 mile commute would be about $0.25 (Huntsville AL rates and my daily commute.) This varies by region and commuting distance but we're looking at an order of magnitude loss of productivity because an employee is encouraged to leave the office for lunch. In effect, L1 charging at work is a low-cost way of increasing employee productivity.

Bob Wilson

Level 1 at work makes some sense IF your commute isn't that long. Keep in mind that if you choose to use the departure time preconditioning, the USA level 1 OUC that comes with the car will not allow you to leave with a full charge, even if you had one earlier.

An interesting point made in the i3 e-book regarding charging the i3 and Li-On batteries was that 10 recharges from 90-100 equals one cycle of 0-100% in ultimate wear on the cells. IOW, a small charge does not count as a 'full' recharge cycle and wear on the batteries. Dumber charging circuits that don't disconnect the charging current can damage cells, but that's not the case with smart devices.