Charging a Roadster with Varying Terminal Voltage

[rolosrevenge]

So I had the opportunity to perform some experiments yesterday with a Sig 100 Roaster. I was charging at 120 V through an autotransformer with variable output to see how the power draw was affected by voltage variations. I've done similar experiments with the company LEAF and observed the following:

• The Roadster is much more finicky than the LEAF when charging. The LEAF doesn't care about big voltage swings from the autotransformer or being plugged in at 140 V whereas the Roadster goes red and says a fault has occurred with a voltage swing and doesn't like to plug into 130+ V at all. When plugged in at voltages above 130V, the charge port would flash blue and then white, and then blue repeatedly. Sometimes it would start charging, immediately stop, then start again over and over. I would have to drop the voltage near 120V, then restart the whole procedure, even closing the charge port to reset it. My friend said he had never seen it do that. The Roadster also would complain about the extension cord repeatedly while the LEAF didn't care.
• The Roadster pulls more current than the LEAF at 120 V. It pulls 15 A compared to the LEAF's 12 A so the Roaster's nominal power is 1.8 kW to the LEAF's 1.4 kW
• The Roadster is a lot noisier at rest while charging. Lots of fans and pumps and things which are expected with the active management of the battery pack.

[frequencydip]

I see this issue all the time my old house has old wiring and I see voltage swing on the lines as much as plus 5 to minus 15. The roadster often stops charging and I have to restart the charge process. I put it on a dedicated circuit and that helped allot. We are putting in Solar this summer and when the installation happens they are redoing the house electrical too, so It be able to charge with clean power at 240volt.

[doug]

Being the rebirth of the EV, the Roadster was designed to be fairly cautions. 130+V is out of spec, so the system is probably playing it safe since it figures something must be wrong. Did you continue going up to see what point the car would start charging again? 208V should be ok, but at that point you probably need a pilot signal. I assume you were using an MC120 (what later became renamed the Spare Connector).

[rolosrevenge]

Yes, I was using the MC120 connector. Once it started charging the current draw caused the outlet voltage to drop so much that even with the auto transformer at maximum (140V potential) I could only get 123V out so I didn't get to observe the behavior at 130 V and beyond. I'm trying to get the equipment to do similar experiments in the 240V range.

[vfx]

It used to be even more finicky. And more complain-y. Over the years firmware has relaxed some of the charge requirements and also added more explanation screens. I'm pretty sure the extension cord screen was not there at first. Also the shutting off was common but only recently has it begun trying again after shutting off. (IMO)

Nissan probably had a Roadster in their engineering Dept when the designed many of the systems. Nice to be 2nd.

[rolosrevenge]

Now it would be really interesting to get my hands on a Model S.

[The_User]

Firmware updates have made things a little better. You can watch as the amps ramp up and volts drop on weak 120VAC outlets. You'll get a warning and the charging stops if volts fall below 115VAC I believe. I've also seen a lot of variability in 220VAC EV stations. I've plugged into some that hold pretty well around 208-209VAC @30amps while others drop to 194-196VAC @30amps. None of those have triggered warnings or stopped charging. It can mean the difference of about 5-6 miles of driving range per hour charged (194VAC vs. 208VAC).

[Doug_G]

Surely it would continue charging at 115VAC. Power derived from three-phase is probably lower than that to begin with.

[rolosrevenge]

We dropped the outlet voltage (very slowly of course) to 100 V and it still charged. The reading on the dash was 98 V. It complained a lot, but the ideal miles did creep up after awhile.

[vfx]

Firmware updates have made things a little better.

I also note the if power is interpreted and returned that the car now begins charging again. That is new. (and appreciated) Tesla Rocks.