Roadster charging

[tomsax]

I have a couple of Roadster HPWCs I could be talked into selling. They are the original Tesla versions, made prior to the ClipperCreek version. Unlike the ClipperCreek versions, they have an easy way to set the maximum charge rate.

Of course, you can always set the charge rate at a given location so that you charge at 30A even if you're plugged into a 70A charger.

Finally, 70A at 240V is 16.8 kW. That's 0.3C for a 53 kWh battery pack. According the Martin Eberhard's blog, A Bit About Batteries, guidance is to stay below 0.5C, so even the 70A charge rate is being nice to the battery pack.

With respect to efficiency, my original study found that charging around 30A was the lowest charge rate that didn't sacrifice efficiency. It got more complicated when I looked at a much larger data set, but the results were similar. We charged our Roadster at 30A when at home, and as fast as we could when waiting for a charge on road trips and our battery held up pretty well.

 

[gregd]

For what it's worth, I wrestled with what sort of home charging setup to get. I didn't want to have to take out and use a CAN adapter each time, but realized that future EVs (or visits from others) strongly favored a regular J1772 connector on the home equipment.

What I ended up doing was to get an OpenEVSE station that included a short 14-50 pigtail and a J1772 charge cable termination. 14-50 outlet was added to the garage, along with a set of dedicated 120v / 20a outlets because they were essentially free. (I can use them with the yellow cord as a backup.) I originally wanted to attach a regular Roadster-terminated cable to the OpenEVSE, but couldn't find one. Instead, I found an original Tesla J1772-to-Roadster adapter cable here on the Forum, and attached that to the end of the charge station cable, with the J1772 connector being just a fat spot in the cable. So, charging the Roadster is simply a matter of taking the cord down off its storage hook, and plugging it in to the car, same action as it would be with a native cable. But having that J1772 in the middle has considerable flexibility benefits. When my daughter visits (she has a Model 3), I disconnect the J1772 from the adapter cable, attach her little adapter snout to it, and plug her car in. On the off chance that I or someone needs the 14-50 outlet, that's a simple matter of unplugging the OpenEVSE, though that's not happened as yet. The 14-50 can also be used with the original Tesla mobile connector that I got with the car, again as a backup to the OpenEVSE. That MC is known to have reliability problems, so I don't use it often. And the OpenEVSE has been rock solid; no issues at all.

I really want to keep the car itself as original as possible, as I think that has value, and carrying the pair of CAN adapters with me in the car is not a problem. If anything, it's a badge of honor that comes with owning this unique piece of history. The Tesla adapter cable stays at home connected to the EVSE. The CAN-JR sits in its pouch in the cabin's cup holder (aka CAN holder); some put it behind the driver's seat, but I move my seat around a lot so that's not a good choice for me. The CAN-SR is less frequently used, so it sits in the trunk. Both have been used during travel, with the SR often giving access to higher power charge stations. I've seen 30 amp J1772 stations sited next to 40 amp Tesla destination stations, making the choice easy. I don't have the JdeMo adapter, though that would certainly be a game changer for some.