Hi - New "S" owner in about 10 days. Sorry if my answer is buried in another post somewhere but couldn't find it. The manual says amperage (and voltage?) "automatically adjusts to max current available from attached cable". I plan to use an extension cable from my garage NEMA 14-50 outlet to the car's cable. But on a trip, want to bring the cable with me as an extension cable for a slow-mo 120 volt overnight charging if say at a friend's house (after attaching a 5-15 or 5-20 120 volt adapter). What triggers the car's automatic adjustment? Is it somehow based on reading the incoming current? Or (my concern) does it register the types/or size of connectors attached to the vehicle's charging cord? My concern is that the car might "see" the 4-prong 220 volt 14-50 adapter and cable, and fail to see that a little further upstream is a mere 120 volt 15 or 20 amp service. Triggering overheated adapter and then breaker tripping, hopefully.
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How the amperage "auto adjusting" works while charging.
- Thread starter RCWtristan
- Start date
There's a resistor in the adapter that you attach to the UMC. It tells the car how many amps to use. If you use only Tesla supplied adapters, you won't have any problem. If you use non-Tesla adapters to plug in, then you'll need to remember to manually adjust the amps.
Don’t do it. If you’re going to draw power from a 5-15 or 5-20 outlet, use the 5-15 or 5-20 UMC adapter and a 15A or 20A extension cord if needed. If you use the 14-50 adapter, the car will try to draw 40A and you don’t want that to happen. You can’t count on remembering to turn down the amps manually in the car, which is what you would have to do with your scenario.
Interesting... Both items attaching to the UMC are from EVSE adapters. So, from the car, which parks 30' away from the 14-50 outlet, first there is the Tesla provided UMC cord. Then the Tesla adapter to attach to NEMA 14-50 cable. Then a EVSE-provided "made for Teslas" 20 foot 6-gauge extension cable with 14-50s at each end. Then, if at an overnight friend's house w/ only 120v power, would be an EVSE-provided "made for Teslas" adapter to attach the 14-50 cable to a 120v wall outlet. So, Morrison Hiker feels like this will be a likely problem because the final link, the 120v adapter, is not a Tesla-sourced item.
Instead if that setup, you could use the UMC and the Tesla 5-20 adapter and then a high quality 20 amp extension cord instead of the 14-50 extension cord. Then it will adjust the amps for you automatically.
JenniferQ
Active Member
Hm. So I thought I had to adjust the amps in the car. Do I understand that if I am simply using the Tesla adaptor from my charger to the dryer outlet that the car will automatically know not to pull too much and trip the breaker? I have it set at 24 amps and wonder if it would choose higher amps if left to its own?
The various plug adapters that Tesla sells for the Tesla Mobile Connector will tell the Mobile Connector how much current it can safely draw. If you're using another extension cord or adapter upstream of the Tesla plug adapter then you're taking a risk. According to Tesla you should not be using any extension cord with the Mobile Connector. I'm not sure what you mean by "EVSE-Provided made for Teslas" adapter. If you're using any adapter that wasn't actually made and sold by Tesla then you'd better know exactly what you're doing and you'd better make sure you dial down the amps in the car. Remember to respect the 80% derating for a continuous load - you can draw 12 amps on a 15 amp circuit, 16 amps on a 20 amp circuit, 24 amps on a 30 amp circuit, etc.
The "made for Tesla" NEMA 14-50 extension cannot provide 120v power, as it does not have a Neutral wire. You will have to carry an additional 120V high capacity extension cord. I suppose if you used an RV 50A extension cord you could put adapters on both ends and make it work, but with questionable gain in the amount of paraphernalia you have to carry.
Whoa, now you're changing what you are talking about! A dryer outlet is NOT 120V, it is 240V at 30 amps. If you plug the MC into the dryer plug directly, Tesla sells an adapter for that. If you need an extension cord, you will need to either get or make an extension with the appropriate plugs and use the Tesla adapter, in which case the amps will be set automatically, or use an adapter at the wall to go to NEMA 14-50, use your custom extension, and plug in the MC to the cord. Before doing that, you need to manually set the charging amps to 24.
Adapters from EVSEadapters do NOT adjust amps as the Tesla UMC adapters do. The “made for Tesla” labeling means nothing. Use the correct UMC adapter from Tesla to avoid potential problems, and if you need a 120V extension cord with it make sure it’s 10 or 12 gauge.
JenniferQ
Active Member
Yes, that's what I've done. I thought upthread that it meant I didn't have to set it at 24 amps, but that somehow the adaptor would "communicate" that to the car. No extension cords! Don't worry. Just charging cable and Tesla NEMA adaptor
BerTx - You mention a good point no one has brought up in this thread yet. Like you say (you obviously know these EVSA products), their 14-50 extension cord does not have a neutral prong or conduit. (has only 3 prongs, not 4). And me thinking that to have it terminate in a 120v adapter for wall plug use might be a problem, I asked them about it.. They say they are fully aware of the issue and "It will work" and they've confirmed on a Model S. See their recent response below. Maybe I just need to see for myself, first manually setting at max of 80% of either 15 or 20 amps, then seeing what the car's system does as I plug in a higher permitted load to see if the Tesla system limits the higher load from coming through... or maybe refuses to charge at all. (Or, just lug around a 2nd extension cord, 10 or 12 gauge, even though I already have a nice heavy 20' of gauge 6 cabling I was hoping to do the trick for both purposes.) -RCWtristan.
Quote:
Hi Bob,
That's right, the Tesla charger does check the polarity and will refuse to charge if wired in reverse. The 120V adapter we sell was designed with this in mind, and we actually tested it with a Tesla Model S to make sure it operates as intended. You can be confident it will work with your Tesla.
Best regards,
John Rowell
EVSE Adapters
On 12/13/2017 04:41 AM, [email protected] wrote:
John - Here’s some blog-comments on Tesla website from someone else basically discussing same concept: use of the 14-50 cord for two purposes. Seems like Telsa charging ‘brain’ is a bit fussy about some of the connections (see last comment) due to the lack of a neutral conduit on your cables. You know if anyone has used the EVSEadapters120 volt adapter on a Tesla? - Bob
From: [email protected]
Hi Bob,
That warning is mainly to keep people from buying it for their RVs. Because this cord (the NEMA14-50) is designed for EV charging, we can keep it as small and light as possible by using just 3 wires - two for power and one for ground. RVs require a four wire cord so it won't work for that application.
We actually offer a 120 volt adapter now which you can use with this extension cord - you can find it here:
NEMA 14-50R to 5-15P 120V Adapter, 2 ft.
Regards,
EVSE Adapters
Email:
[email protected]
Body:
...However, I just re-read the spec on the 20' NEMA 14-50 cord you sell. It says the Neutral prong is not present which allows it to be used for other purposes. And thus I am now thinking maybe the heavy cord could not be used as a 110 volt extension cord for regular wall socket slow-charging. The description says the neutral prong is for supplying 120 volt power and thus not needed by elec veh chargers. Is this right? Should I have bought a different NEMA 14-50 cord that would have also served to use as an extension cord for 120 volt slow-charging (with adapter)? - Bob Wenneson
Quote:
Hi Bob,
That's right, the Tesla charger does check the polarity and will refuse to charge if wired in reverse. The 120V adapter we sell was designed with this in mind, and we actually tested it with a Tesla Model S to make sure it operates as intended. You can be confident it will work with your Tesla.
Best regards,
John Rowell
EVSE Adapters
On 12/13/2017 04:41 AM, [email protected] wrote:
John - Here’s some blog-comments on Tesla website from someone else basically discussing same concept: use of the 14-50 cord for two purposes. Seems like Telsa charging ‘brain’ is a bit fussy about some of the connections (see last comment) due to the lack of a neutral conduit on your cables. You know if anyone has used the EVSEadapters120 volt adapter on a Tesla? - Bob
From: [email protected]
Hi Bob,
That warning is mainly to keep people from buying it for their RVs. Because this cord (the NEMA14-50) is designed for EV charging, we can keep it as small and light as possible by using just 3 wires - two for power and one for ground. RVs require a four wire cord so it won't work for that application.
We actually offer a 120 volt adapter now which you can use with this extension cord - you can find it here:
NEMA 14-50R to 5-15P 120V Adapter, 2 ft.
Regards,
EVSE Adapters
Email:
[email protected]
Body:
...However, I just re-read the spec on the 20' NEMA 14-50 cord you sell. It says the Neutral prong is not present which allows it to be used for other purposes. And thus I am now thinking maybe the heavy cord could not be used as a 110 volt extension cord for regular wall socket slow-charging. The description says the neutral prong is for supplying 120 volt power and thus not needed by elec veh chargers. Is this right? Should I have bought a different NEMA 14-50 cord that would have also served to use as an extension cord for 120 volt slow-charging (with adapter)? - Bob Wenneson
MORRISON HIKER - You're right. Would be simpler and would eliminate the confusion/risks discussed her. I was just try to eliminate having to carry a 2nd extension cord. Already have the 14-50 cord for my home setup, and I figured to take it on a trip as it could also be used at the many RV parks with 14-50 setups in a pinch, and it would also serve as my slo-mo extension cord for 120 v wall charging. Without having to carry another 25 or 50 feet of 120v 20 amp extesnison cord...
The Tesla NEMA 14-30 adapter WILL set the amperage to 24 automatically. The Tesla NEMA 14-50 adapter will set the amperage to 40. Using an non-Tesla adapter to go from NEMA 14-30 to NEMA 14-50 and using the Tesla NNEMA 14-50 adapter on the MC will NOT set the amperage automatically -- by putting the Nema 14-50 adapter on the MC, you tell the car it is connected to a 50 amp circuit, and it will try to charge at 40 amps. You must set it manually.
You could get NEMA 5-15 adapters for both ends of an RV (not the made for Tesla one) NEMA 14-50 extension cord.and do what you want. By the time you get the heavier extension cord and the two adapters, you won't save any space (or money) and will triple the number of connections.
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