Dear Energy Coach: I bought an EV and have been making do with Level 1 charging. According to the load sheet, I need a transformer upgrade, but my EV has a 7.2 kw onboard charger, which isn’t close to the 12 kw load of the Level 2 charger that would overload my transformer. What gives? Why can’t you give me a Level 2 charger set to 7.2 kw now?
Member, I hear you. It’s annoying to be in your position. First, let’s make sure we all know what equipment we’re talking about here: the onboard charger is the device within your EV that changes AC power from your home electricity to DC power in order to recharge your EV’s battery. When you charge at a “fast-charging” station, you apply DC power directly to your battery, bypassing your onboard charger; but when you charge at home, you use AC power and the EV’s onboard charger.
The reason you’re on the transformer upgrade list is because your cooperative utility must assume that the maximum capacity your device or vehicle can handle is what it will handle. So even if you’re at 7.2 kw, the Level 2 charger can power up to 12 kw. WEC, along with any other electric utility, has to assume that you will use 12 kw, because that’s what the charger can handle. For comparison purposes, a Level 1 charger powers 2.4 kw or less.
So our offer to our members is based on an additional 12 kw demand. And that offer is this: we’ll provide you with a Level 2 charger, at no cost to you, which has six settings up to 12 kw. That’s the good news. The bad news is, if the assumed new maximum demand of 12 kw of new load is more than your transformer can handle, you need to get on the list for an upgrade. And because the supply chain is still pinched, it may take a while.
There’s a workaround. I want to be honest with you, since I understand the urgency, and I also want you to understand that it carries risks.
Since you’re waiting for a transformer upgrade, you may decide you don’t want to wait for the 12 kw charger WEC will give you. You’ll buy your own, and you’ll install it at 7.2 kw to avoid imposing the 12 kw load. And you can do that, though I encourage extreme caution and a thorough understanding of what you’re doing. If you do overload your transformer, and you blow the fuse, you will cause an outage. Crews will have to come fix it. And this will cost you money.
That’s the takeaway. If you buy your own charger and install it so you’re well within your load capacity, you’ve got your Level 2 charger, and you’re ahead of the game. But if you blow the fuse, you’re behind the game, and you paid out of pocket for a Level 2 charger.
Have an energy question? Ask the Energy Coach: energycoach@wec.coop