NEMA TT-30

[PhilBa]

I didn't say all. I had them put 20A breakers for the outlets in my new garage but it is rare for almost all older homes (20+ years) that I've lived in.

 

[gregincal]

If they had limited 120 charging to 12 amp I would have said, "OK they're just going for the common case." But a 20 amp limitation doesn't make any sense as a cutoff.

 

[fluxemag]

I made a custom TT30 adapter using advice from this forum, but haven't actually tried it out yet. There's an outlet in the parking lot at work for the old trailers that used to be out there.

 

[Incredulocious]

I've been looking into getting a TT-30 adapter to use with a modified Tesla Mobile Connector (modified to have a J1772 plug) for my 2013 RAV4 EV. (Perhaps in the form of a 14-30 or 14-50 to TT-30.)

I wrote to Tesla today via their online store contact to ask for a direct adapter (calling attention to this thread) and received this response already:

Thank you for contacting Tesla Motors. We appreciate your feedback and the request for the NEMA TT-30 adapter. We have had several requests for this adapter and the charging team has been informed. We are optimistic that the TT-30 will be considered for addition to our adapter lineup in the future.

Regards,
Hugh

 

[islandbayy]

And in real life nobody's ever got close to 8mph from 120 (it's much less efficient). My guess is that you'd get more like 4-5 miles per hour of charging.

Ive gotten 6mph from a 120v 20 amp outlet (16amp charge rate). Without the voltage drop on the line, I might have gotten 7 or 8. Using a TT-30, heavier gauge wiring, should not have the voltage drop. Still, it will beat a 15 amp 120v.

 

[bluetinc]

The real key to Tesla making a real TT-30 adapter is that they "Should" also change the cars software at that time to allow 24 Amps at 120V whereas now we are limited to 20A by the car.

Peter

Ive gotten 6mph from a 120v 20 amp outlet (16amp charge rate). Without the voltage drop on the line, I might have gotten 7 or 8. Using a TT-30, heavier gauge wiring, should not have the voltage drop. Still, it will beat a 15 amp 120v.

 

[glhs272]

It might be the case that the 20Amp limit on the charger at 120 volts is an actual hardware limit, not just a software thing. Meaning it needs the full phase to pull 40amps (it splits the 240 volt full phase into two 120 volt split phase 20amp circuits). Just a guess. Although if the car were equipped with dual chargers, then maybe more than 20amps is possible.

 

[bluetinc]

Nope, I can definitely say dual chargers doesn't help

It might be the case that the 20Amp limit on the charger at 120 volts is an actual hardware limit, not just a software thing. Meaning it needs the full phase to pull 40amps (it splits the 240 volt full phase into two 120 volt split phase 20amp circuits). Just a guess. Although if the car were equipped with dual chargers, then maybe more than 20amps is possible.

 

[glhs272]

Yeah that's a bummer.

 

[Cosmacelf]

I very much doubt the 20a 120v limit is in hardware. I suspect software and an over zealous programmer.

 

[Cottonwood]

I very much doubt the 20a 120v limit is in hardware. I suspect software and an over zealous programmer.

I agree! I am pretty sure that Tesla could come out with a software update that would support a TT-30 adapter to charge at 24 Amps.

Has anyone looked at the PWM signaling coming out of the UMC during 120V charging? This could be firmware in the UMC that notices the 120V and limits the PWM to the car to 20A, but I doubt that. If the limit is in the UMC, and update would be more difficult.

 

[Cosmacelf]

Btw, why the renewed interest in charging from a TT-30? They aren't that useful...

 

[Cottonwood]

Btw, why the renewed interest in charging from a TT-30? They aren't that useful...

When living off the land, it's always good to have a diverse bag of adapters. I have only encountered one location that only had a TT-30, but 24 Amps is better than 20 Amps is better than...and I will probably go back there next summer.

Every little bit helps. :wink:

 

[Cosmacelf]

Does that site have two TT-30s? I ask because I built myself a TT-30 combiner to get 240v from them...

 

[Cottonwood]

Does that site have two TT-30s? I ask because I built myself a TT-30 combiner to get 240v from them...

Interesting thought, but I only had access to one TT-30. They have a few, but the TT-30's are kind of scattered; it's an overnight, summer camp that I support. I believe in being prepared, but probably won't go to the trouble of building such a "two 120V to 240V" adapter for once a year use.

 

[bluetinc]

Yes, I've tested this with my own EVSE and the limit is definitely in the car.

Peter

I agree! I am pretty sure that Tesla could come out with a software update that would support a TT-30 adapter to charge at 24 Amps.

Has anyone looked at the PWM signaling coming out of the UMC during 120V charging? This could be firmware in the UMC that notices the 120V and limits the PWM to the car to 20A, but I doubt that. If the limit is in the UMC, and update would be more difficult.

 

[N8DGR8]

http://cosmacelf.net/Home Made Adapters.pdf

Page 7.

Stick with the Campco parts, I tried the Conntek TT-30 plug and one leg started to melt slightly. I was charging at 24 amps / 8 mph.

From the RV forums, it sounds like this is a common problem with TT-30 outlets where the outlet is worn.

 

[Cosmacelf]

I think you meant to say Camco...

 

[InternetDude]

Stick with the Campco parts, I tried the Conntek TT-30 plug and one leg started to melt slightly.

Do you have a photo? I have one of the Conntek adapters on its way to me, I bought it from eBay.

 

[InternetDude]

Update, it turns out the Conntek adapter I got was the standard RV one. I switched two wires inside the adapter to modify it and it works like a charm.