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LuckyLuke
Model S P90DL
No need to cut apart, just measure what pins are connected and what resistance is on the pilot pin. For the EU UMC it is a resistor between pilot and ground, see this page: http://www.teslamotorsclub.com/showwiki.php?title=European UMC adapter resistor coding
Brass Guy
Active Member
I don't remember where this came from and cannot vouch for accuracy.
Tesla UMC Plugs Resistance
40 amps - 9.08k ohms
24 amps - 33.16k ohms
16 amps - 75k ohms
12 amps - 140k ohms
IIRC, the resistor is between the ground and signal pins.
In theory, you could turn a 5-15 adapter into a 5-20 by paralleling ~160k ohms on the adapter.
Tesla UMC Plugs Resistance
40 amps - 9.08k ohms
24 amps - 33.16k ohms
16 amps - 75k ohms
12 amps - 140k ohms
IIRC, the resistor is between the ground and signal pins.
In theory, you could turn a 5-15 adapter into a 5-20 by paralleling ~160k ohms on the adapter.
Brass Guy
Active Member
I was thinking the exact same thing. So I can't fool the 14-50 adapter to reduce to signal a 30A circuit without wrecking it, you can only increase it with resistors in parallel.
While I'm sure the 5-15 adapter would have no problem at 16A, I decided it's not worth the risk of melting it with 24A. So I use the 14-50 and dial down in the car. I don't like it, but have no other option for 2 weeks out of the year.
The best thing to do is to have the correct Tesla adapter (by current rating), then build adapters for whatever outlet you need. All you'd need is the Tesla 5-15, 5-20, (x)-30 and 14-50 adapters; and you could make any adapter you like for it.
Unfortunately, looking at the web site it doesn't look like Tesla sells any adapters at 30A anymore.
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While I'm sure the 5-15 adapter would have no problem at 16A, I decided it's not worth the risk of melting it with 24A. So I use the 14-50 and dial down in the car. I don't like it, but have no other option for 2 weeks out of the year.
The best thing to do is to have the correct Tesla adapter (by current rating), then build adapters for whatever outlet you need. All you'd need is the Tesla 5-15, 5-20, (x)-30 and 14-50 adapters; and you could make any adapter you like for it.
Unfortunately, looking at the web site it doesn't look like Tesla sells any adapters at 30A anymore.
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This is an interesting idea. This would be better than my current solution for 30A.
What I'd like is a 14-50 with the resistor for 12A. Then all the other adapters I've made, which plug into the 14-50, could be equipped with parallel resistors to up the allowed amperage to whatever was correct for that adapter.
Brass Guy
Active Member
... until you plug that 14-50 into a 14-50 and get 12A!
How would this work? I think you'd have a lead hanging from the signal pin between the 14-50 adapter and the UMC's input, and manually clip whatever resistor you left hanging on your custom adapter.
RDoc actually has a good idea... I like it. You could create a passthrough approach with resistors in parallel, each "box" has a different resistor value.
Think extension tubes for cameras. You have a small, medium and large tubes for various macro shots, and you can use any of the 3, or stack 2 of them or stack all 3.
Same would apply with the UMC, the resistor rings, and the modified 14-50 adapter. Without any resistor rings, you'd get 12A (140k ohms), each resistor ring can be color coded to reduce the total resistance when added in parallel to get to the next higher charge rate.
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Or even simpler, create the modified 14-50, create 1 step-ring and a potentiometer, and have labels to the 3 values you need to achieve the 4 cutoffs
No, you're right, I was thinking the resistor could be in the plug, but obviously that's not true, it has to be from the signalling pin. Wouldn't work.
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That's a good idea, but unfortunately, I can't claim any credit for it. :crying:
My objective was to fill in my kit with 120V adapters for cheap (since I hope to never use them). I bought a TT30 (RV 120V connector) to 14-50 adapter. Opened it and rewired the neutral connection. With another 5-15 to TT30 adapter, I can connect to any 120 V outlet and pull up to 40 amps @ 120V. Actually a dangerous level to operate the UMC at continuously. But with the ability on the car console, to explicitly set the current drawn, I can set it to 12, 16, 24, 30 or any other value I want, depending upon what I am plugged in to. Total cost: less than US$30.
Basically, any time you use the 14-50 UMC adapter, you are limited to 40 amps. But you can turn that down to any level you need. The only problem is you end up with quite long adapter stack. It may have to propped up on something to stay plugged in. But remember this is a last resort hack to get you out of a jam. Not supported at all, but it beats walking!
Basically, any time you use the 14-50 UMC adapter, you are limited to 40 amps. But you can turn that down to any level you need. The only problem is you end up with quite long adapter stack. It may have to propped up on something to stay plugged in. But remember this is a last resort hack to get you out of a jam. Not supported at all, but it beats walking!
TonyWilliams
Active Member
Doubtful. The Gen 2 UMCs have electronics in the adapters including temperature sensors, so you probably can't easily build your own adapters that would hook directly to a Gen 2 UMC.
What plugs are you needing an adapter for that Tesla doesn't have available?
The couple extra I currently will need, they offer. I was thinking of having even more to be ready for what I might need without spending $200 and taking up as much space. Have a female 14-50 with some wire and be able to swap plugs if I come across a new one. I live over an hour from the nearest Tesla store and will do most of my driving farther away from one. So a hardware store would be my best option and I could have all the resistor sizes ready.
I've added a 20k resistor to the socked of my UMC (EU type) and now the max set current is 32A enabling me to draw 7kW from 220V line. I've tried to use 16A for several hours and there is no sign of over heat of the cable and the wall socket by observing from my IR camera.
The yellow wire is very thin (wire-wrapping wire)
The yellow wire is very thin (wire-wrapping wire)
I found it easier to buy 6-50 socket to go with 6-50 extension cord. Then get a few plugs with cords. Easy to find since people frequently need them when installing appliances.
So far have both types of US dryer cords. Didn’t know which type was at beach house. When we arrived, I checked then attached appropriate dryer cord to the socket. Cut the connector off the neutral wire and securely taped it.
Next might be range plugs, which also come with cords.
Tesla remembers the charge Amps you set at a location. Only have to be alert the first time you use a 6-50 adapter somewhere.
You should really check every time. There have been examples of the car forgetting the reduced charge rate settings after a software update, or if the GPS is confused.
Hello there. You just add a 20k resistor? What about the 100k original resistance? Thanks
