I have been charging my 2018 Long Range M3 at home for 5 years. I set the amps at 24 on a 30 amp 240 volt circuit. This has worked great for me. Recently it started randomly changing the amp setting from 24 to 48. This happens even when I'm not charging. I just reset it to 24. Recently it startted changing to 48 while its charging. This trips the breaker. It doesn't seem to be a connection issue as it changes the amp setting when I'm not charging too.
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Amp setting chnges on its own from 24 to 48 amps
- Thread starter rbet
- Start date
It shouldnt be possible for your car to "set the amps to 48" if you are using the proper charging equipment, and its setup properly, so you should start with examining the setup for whatever you are using as charging equipment, and ensure IT (the charging equipment) is setup for being a 30 amp circuit.
Wall Connector, Mobile Connector or some other third party charging unit?
If Wall Connector, what is the maximum amps setting on the unit itself?
If Mobile Connector, what type of receptacle is it plugged into?
If third party, what is it and what is it plugged into?
If Wall Connector, what is the maximum amps setting on the unit itself?
If Mobile Connector, what type of receptacle is it plugged into?
If third party, what is it and what is it plugged into?
RayK
Active Member
I would pull out the NEMA adapter from the mobile connector, look at the terminals to see if there's any dirt / debris / oxidation / etc. and if none, plug it firmly back into the mobile connector. Then try using it again.
BTW, if this is indeed a genuine Tesla mobile connector and NEMA adapter, you should never have to manually set the charging amps to 24. It should automatically be there when you connect up. If you have had to manually set the amps, then there's something wrong with the NEMA adapter, the mobile connector or your car's charge port. Doubt that this is a software issue but if it is, then manually re-boot the car (two thumbwheel reset) and see if that helps.
BTW, if this is indeed a genuine Tesla mobile connector and NEMA adapter, you should never have to manually set the charging amps to 24. It should automatically be there when you connect up. If you have had to manually set the amps, then there's something wrong with the NEMA adapter, the mobile connector or your car's charge port. Doubt that this is a software issue but if it is, then manually re-boot the car (two thumbwheel reset) and see if that helps.
Others have mentioned the gps current limits getting lost.
But, ideally, you should have a charging setup that automatically limits current based on the outlet. I know there were a lot of adapters used in the past that bypassed limits. But Tesla has continued to offer more adaptor options…
Sounds like you don’t have a setup that is safe by current standards?
But, ideally, you should have a charging setup that automatically limits current based on the outlet. I know there were a lot of adapters used in the past that bypassed limits. But Tesla has continued to offer more adaptor options…
Sounds like you don’t have a setup that is safe by current standards?
RayK
Active Member
I believe that before you connect the external charging equipment to the car, the car's display will show 48A (or the maximum for your car, which can be 32A for SR). It should automatically change to whatever NEMA adapter you are using just prior to the start of charging. If you are using a 14-30 NEMA adapter with the mobile connector, it should cause the car to be limited to 24A. If it's going higher than that, then there's a problem with either the NEMA adapter, the mobile connector or the car. My bet would be with the connection between the NEMA adapter and mobile connector. That's why I suggest you re-seat the adapter.
We still don't know what type of adapter you are using. A photo of the plug would help a lot.
We still don't know what type of adapter you are using. A photo of the plug would help a lot.
E90alex
Active Member
You should not be relying on dialing down the amperage in the software to stay within your circuit limits. The car should communicate with the EVSE as to what amperage the EVSE can supply. With the correct adapter on the UMC, it should automatically limit you to 24 amps on a 30 amp circuit and not allow you to go above that.
Something is wrong with your setup because if you’re using the UMC then it’s impossible for the mobile connector or car to even pull 48 amps. The Gen 2 UMC maxes out at 32 amps. Gen 1 UMC and Corded Mobile Connector max out at 40 amps. Only way to get 48 amps would be a hardwired EVSE like the Tesla wall connector or similar third party hardwired unit, not something that plugs into a dryer outlet.
Something is wrong with your setup because if you’re using the UMC then it’s impossible for the mobile connector or car to even pull 48 amps. The Gen 2 UMC maxes out at 32 amps. Gen 1 UMC and Corded Mobile Connector max out at 40 amps. Only way to get 48 amps would be a hardwired EVSE like the Tesla wall connector or similar third party hardwired unit, not something that plugs into a dryer outlet.
The Mobile Connector cannot charge at anything more than 32A, so it should never tell the car a 48A draw. So either the Mobile Connector has died and is giving incorrect info to the car, or you are using a Wall Connector.
The car will default to 48A when nothing is connected because that's the maximum it can charge at. But once you have a Mobile Connector plugged into a live circuit which is then plugged into the car, it will tell the car the maximum current it should draw, which would be 24A ASSUMING you are using an actual Tesla dryer adapter for the Tesla Mobile Connector (ie. a NEMA 14-30 or NEMA 10-30 adapter). You haven't told us or shown us the adapter you are using.
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ucmndd
Well-Known Member
No, it didn’t.
The car will ALWAYS display 48a when not charging or connected to charging equipment.
How do you know this? Document it. This isn’t what’s happening.
Something else is tripping the breaker. It’s NOT due to the car pulling too much amperage. You’re misinterpreting the signals the car is giving you.
E90alex
Active Member
This. Most likely something else is tripping the breaker and since technically the EVSE is then no longer connected to power, the car is showing the 48 amp default when “unplugged” even though it’s still physically plugged in.
I thought this was a duplicate thread, because it sounded exactly the same as this one from Friday:
teslamotorsclub.com
My tesla reverts back to 48 AMP on its own after I configure 30 amps max charge after 5 mn (NO wall charger).
My tesla 3 reverts back to 48 AMP on its own after I configure 30 amps max IN THE CAR ITSELF after I charge 5 mn. I am NOT using a wall charger just a electrical cord on a 30 amps outlet. My breaker trips all the time. What is wrong?
teslamotorsclub.com
No it isn't. As a few people have covered, whenever the car is not connected, it will display the maximum capability of the onboard charger, which is 48A. If your circuit trips, the car is disconnected, so it thinks it's not plugged in, so it will revert the display to showing 48A. That has nothing to do with why your breaker tripped, which is what you need to actually try to figure out.
It is technically possible for the UMC to have failed and be telling the car that it's hooked to a 48A+ source. The current limit is communicated to the car via a PWM signal on one of the pins, and calculated by logic inside the UMC, and I see no reason that this can't have some failure modes.
Unlikely, but possible and doesn't require software issues or other weirdness. If you're convinced nothing else is hooked to the circuit that could be popping the breaker, then this is where I would start.
Unlikely, but possible and doesn't require software issues or other weirdness. If you're convinced nothing else is hooked to the circuit that could be popping the breaker, then this is where I would start.
...but finish that line of thinking. The mobile connector cord is only built with the physical capability of supplying 32A. So if it sent a wrong amp signal to the car, and the car tried to pull more, it would melt the mobile connector down into a puddle of goo before or at the same time it could get to the circuit. That isn't happening, so that explanation doesn't seem possible.
ucmndd
Well-Known Member
But technically not possible for said UMC to provide 48 amps of current like OP thinks is happening.
It's built for 32A in extreme conditions like being outside in direct sunlight, yet here we're likely in a nice cool indoor space, given we're using a dryer plug.
Anything built for broad consumer use in these conditions easily has a 1.5X safety factor.
You really think stuff inside is completely fine at 32A but would melt at 48A? Nothing in the safety critical consumer space is built with that little margin.
Do you really think that if you pulled 55A on a 50A rated wire in your house that the expected outcome is fire?
You should take a look at Tesla's 80A Wall Connector and the cabling there and really question if the UMC looks like it would just melt into a puddle at 1/2 the current.
The UMC is literally just a relay between the outlet and the car. It doesn't regulate power or convert it at all. When plugged into a 50A outlet, what would prevent it from "providing" 48A?
It appears people have a fundamental misunderstanding of what an L2 EVSE is and what occurs inside. It's just a relay/contactor so that the connector on the end can't shock a human and doesn't have any voltage on it until safely plugged into a car. It also signals to the car the max current that can be utilized based on what circuit it's connected to. It's up to the car to not draw more current than commanded, and the EVSE doesn't have to protect for overcurrent.
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