Little help planning my first long-ish trip?

[Rocky_H]

I believe I was around 50%. No other cars at all.

You did say it was only an hour away from your house, so I figured the 70kW is just the natural tapering of the charge speed based on your existing level of energy in your battery. Yes, you can get over 100kW when your battery is nearly empty, but it's going to be down to 20kW and 10kW and less when it's almost full, and it's a nearly linear progression all the way through.

Here's a handy rule of thumb to see if your charging speed is about normal due to tapering or whether something is artificially slowing it down. Add together your state of charge in percent and the kW power level. Those two added together should be somewhere near 120, plus or minus maybe 5-7 because it's not strictly linear the whole way. In your case, you had 50% + 70 kW, so it was dead on at 120 and totally normal.

That is great that you were able to get a dryer outlet adapter made. What exactly is it adapting to? If it goes from the official Tesla 14-50 on your mobile charge cable to a dryer plug (10-30 or 14-30), just keep in mind that the Tesla charging system cannot detect that you're adapting to a 30A circuit. Turn the charging rate in the car down to 24A or less to have the proper load for a 30A circuit like that. But if you've built your adapter cable from the Tesla 14-30 to a 10-30, that is already at the proper circuit rating, so it will automatically set that 24A limit for you.

 

[bcsteeve]

Those two added together should be somewhere near 120, plus or minus maybe 5-7

Great tip, thank you! I was observing/reporting what I got, not complaining. It was no problem at all, it just seemed low to me. Now I know!

That is great that you were able to get a dryer outlet adapter made. What exactly is it adapting to? If it goes from the official Tesla 14-50 on your mobile charge cable to a dryer plug (10-30 or 14-30), just keep in mind that the Tesla charging system cannot detect that you're adapting to a 30A circuit. Turn the charging rate in the car down to 24A or less to have the proper load for a 30A circuit like that. But if you've built your adapter cable from the Tesla 14-30 to a 10-30, that is already at the proper circuit rating, so it will automatically set that 24A limit for you.

Home made adapter using a dryer cord that had the right male and four bare wires on the other, which I attached to a NEMA 14-50r in a standard junction box. Fed it through a window and it worked like a charm. Yes, I turned it down to 24A. My great uncle came over later... he was a utility electrician for decades. He told me to put it to 35A, because he wanted to see if it got warm and to test the half century old breaker. It tripped after half an hour. What's interesting is that when we flipped the breaker back and did NOTHING else, I saw in the app that the charging automatically reduced to 30A! I wasn't expecting that. He told me to leave it there, and I humored him by not wanting to ruin Thanksgiving dinner (Canadian Thanksgiving was this weekend) by burning the place down... I quietly put it back to 24A for the rest of the night.

 

[Rocky_H]

What's interesting is that when we flipped the breaker back and did NOTHING else, I saw in the app that the charging automatically reduced to 30A! I wasn't expecting that. He told me to leave it there, and I humored him by not wanting to ruin Thanksgiving dinner (Canadian Thanksgiving was this weekend) by burning the place down... I quietly put it back to 24A for the rest of the night.

Yes, that's a built-in safety feature that the Tesla charging system has. You were using the official Tesla 14-50 plug on the UMC. The system will try to use 40A as a default for that. If it runs into a charging problem, like a bad voltage drop (detecting possible wiring problem), or in your case, a cutoff of the circuit because of the breaker, it will attempt to restart charging at three fourths of the regular level--in this case 30A instead of 40A.

This does bring up why adapting a 50A plug type to a 30A plug type is not necessarily something you want to use all the time as your daily charging situation. Let's say you did have this set to 24A and went to bed. If there were some kind of interruption, it may restart at 40 or 30. Wiring for North American electric code is not rated to allow full current usage of a circuit continuously, so 30 out of 30 might heat up the wiring, and hopefully (!) would trip the breaker before a fire.

I have a preferred option for those kinds of situations to avoid this rare but unsafe condition. Now that Tesla sells a 14-30 plug, you can get one that always keeps the current at 24A or less. The "L" shaped neutral pin would prevent it from plugging into your 14-50 outlet box, but the Tesla charging cable doesn't even use that neutral pin; it's actually disconnected inside the adapter. I haven't gotten around to it yet, but I'm going to use my Dremmel to cut the neutral pin off, and then I can plug it into the other adapters I had already bought that have those 14-50 receptacles on them. 10-30 (old dryer outlets) and TT-30 (camping trailers) are the ones that would be useful for. I got that suggestion from others on this forum who have done it.