Depends on how to want to configure it. It requires #3 for the 100A setting. But you can also configure it for 64A charging / 80A breaker (#4 wire), 48A charging / 60A breaker (#6 wire in conduit only / no NM-B), 40A charging / 50A breaker (#8 wire in conduit or #6 NM-B), and a few lower than that.
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Charging cuts down to 75%, Tesla says... it's my house.
- Thread starter SabrToothSqrl
- Start date
Depends on how to want to configure it. It requires #3 for the 100A setting. But you can also configure it for 64A charging / 80A breaker (#4 wire), 48A charging / 60A breaker (#6 wire in conduit only / no NM-B), 40A charging / 50A breaker (#8 wire in conduit or #6 NM-B), and a few lower than that.
My setup also kicks back to 48A charging frequently (I'm dip-switch set for 80 amp breaker/64A). Does anybody know what the logic is inside the car to trigger fallback? In my case, I can see my voltage drop as the current ramps up, starting at like 235 volts and dropping to 226 volts at 60A, before it kicks back to 48A. My car is currently set to limit charging to 60A.
I wonder if Tesla would let us know what the algorithm is? That would greatly help diagnose this problem.
I wonder if Tesla would let us know what the algorithm is? That would greatly help diagnose this problem.
There are two components to it - one is what I call the "extension cord detection" that looks for an abnormal voltage drop as the charging current increases. Given that you're starting with 235V, you may be hitting this one because 226V is considered out-of-spec for the US 240V service (5% tolerance means 228V - 252V is considered in-spec). If you know what you're doing, you may want to measure the voltage at your garage panel while the car is charging at full load. A drop from 235V to 226V is more than what I would expect for 64A - at 80A, but you mentioned you only had room for 100A to your garage. I think some others have noted here that there is a threshold around 226-228V where the car will drop its charging current to 75%. You might call your power company and tell them that under the car's charging load, you're seeing your voltage drop to 226V in your garage and ask if they can boost your voltage just a bit so that it's slightly higher.
The second component is the more intermittent problem that some others see, and that's the one that's harder to track down - we don't know the algorithm but suffice it to say that it's more complex than the voltage drop scenario. Certain misbehaving appliances and other load issues can trigger it.
How often does it back off for you? 25% / 50% / 75% / 100% of the time? You noted that when you have the car charge at 60A instead of 64A that it doesn't back off. It may be the case that your wiring run to the garage is too long for the conductor that you're using and you'll have to limit to 60A.
I'm suspecting that my wiring run to the garage is a bit undersized. I'm hoping to grab a wire gauge tool later on the way home and see exactly what I have. The panel was installed with a 100A main breaker a long time ago (20 years ago), but I'm not sure of the wire size for the main feed. I'm a EE but not really a power guy, so I can definitely slap my meter on the panel main while the car charges and see what's happening.
I was incorrect when I said backing off to 60 solved it. It 'seemed' to solve it at the time, but it's still triggering at least 75% of the time. I've only had the car for a week now, so this is all pretty new to me.
What I plan to do over the next few days is keep backing the car off 2A at a time while charging and find my sweet spot.
I was incorrect when I said backing off to 60 solved it. It 'seemed' to solve it at the time, but it's still triggering at least 75% of the time. I've only had the car for a week now, so this is all pretty new to me.
What I plan to do over the next few days is keep backing the car off 2A at a time while charging and find my sweet spot.
There was some data in that other thread that concluded if the voltage dropped below 228, it was likely to trigger the charging back-off. I suspect that it's related to your feeder to the garage.
I would meter your panel's bus inside your house while the car is charging, then based on what it reads you may be able to get the power company to use a slightly higher-voltage winding for you.
Good luck!
Cottonwood
Roadster#433, Model S#S37
@FlasherZ: Nice summary of the triggers for the 75% current back offs.
@chuckd: As an EE, you understand IR drops well; ∆V = ∆I*R or R = ∆V/∆I. You can measure resistance between various points by measuring ∆V with a ∆I. Your Model S is a great way to add in and remove a known ∆I. With 2 people, this can go pretty fast. Good places to measure Voltage (if you are comfortable, and know how to be safe) are your main panel and the garage sub-panel. While it only has integer Volts resolution, I have found the Tesla display of Voltage to be good.
American wire gauge - Wikipedia has a good discussion on wire gauges, and Wire gauge size caculator is a good calculator of wire parameters. Remember that the diameters are for solid wire, and connections always have some extra resistance. With the current flowing, I will often measure Voltage drop across connections, breakers, etc to see if there is a problem.
Kbra
Member
In CA the utility is expected to stay within +/- 2%. Not sure about PA but it's def worth a call to your utility. Given the age of your home I doubt the issue is on your side and most likely utility distribution.
If his garage is provisioned for only 100A, and it's a longer run, it may be smaller conductors. I would measure at the service panel (home's main panel) with the car charging to see where the voltage is.
Well, I can only assume PPL installed the gizmo, however the last three charge cycles, some up to 5 hours, have all been at a solid 40 amps the whole time. I changed nothing on my side... My panel is 200 amp service, and this is my UMC. I may at some point buy a HPWC, which would be set to 80 amp.
I don't mind if the issue has been fixed, but I was hoping to know what it was...
I don't mind if the issue has been fixed, but I was hoping to know what it was...
Charging data
Been looking over Visible Tesla logs in excel. No issues charging at 40 amps since 3/31...
of course now that I post this...
Been looking over Visible Tesla logs in excel. No issues charging at 40 amps since 3/31...
of course now that I post this...
Also good to check: Aluminum conductors tend to corrode and loose conductivity at the terminations after time. If you have Aluminum conductors they may need to be re-terminated.
EVSteve
110% Solar Powered
Also on PP&L here in PA. We had issues with our solar inverters cutting out anytime we pushed more than 8,000 watts towards the grid due to the transformer at the pole not being adequately sized for the amount being pushed back. PP&L hadn't considered this factor when they approved the installation. At first the thought was undersized wiring on the run from the array to the house (its a ground mount about 300' away) but after PP&L installed the logging device they quickly realized what was happening. The 10kVa transformer wasn't enough so they upgraded it to a 50kVa as I had let them know of the coming HPWC and that we already had twin 7.2kW chargers for the Volts.
We also used to have dimming lights as you described. After the change the lights don't dim even with a Tesla pulling with dual chargers and both Volts charging at 3.3kW. Zero in on that transformer! If you can while their logger is attached draw as much amperage as you can. The idea is to pull the line voltage down below the PUC requirement to force them into upgrading your transformer. If they're out of spec they have to by law. Adding a logger of your own is also a great idea. I can help with that if you'd like.
We also used to have dimming lights as you described. After the change the lights don't dim even with a Tesla pulling with dual chargers and both Volts charging at 3.3kW. Zero in on that transformer! If you can while their logger is attached draw as much amperage as you can. The idea is to pull the line voltage down below the PUC requirement to force them into upgrading your transformer. If they're out of spec they have to by law. Adding a logger of your own is also a great idea. I can help with that if you'd like.
Well, my problem is definitely caused by my garage feeders. As my current ramps up, my voltage drops significantly at the panel main (starts at like 235 volts, and gets down to 226V when it gets to about 55 amps). At the house itself, voltage is still strong around 237. I'm pretty much out of luck charging at higher currents unless I want to tear out lots and lots of concrete.
Seems to me that 200+ feet of feeder wire shouldn't get too hot with this much current. Can't Tesla just let it go this once? Lol
Seems to me that 200+ feet of feeder wire shouldn't get too hot with this much current. Can't Tesla just let it go this once? Lol
beeeerock
Active Member
Installed
PP&L installed their spy equipment today. I was able to get the car to trip down to 30 amps as well... I didn't actually do anything. In fact, when I tried to do it, by running everything I have, it wouldn't.
If a moderator wants to rotate my photos, please do.
Im having other charging issues, but that's another thread.
PP&L installed their spy equipment today. I was able to get the car to trip down to 30 amps as well... I didn't actually do anything. In fact, when I tried to do it, by running everything I have, it wouldn't.
If a moderator wants to rotate my photos, please do.
Im having other charging issues, but that's another thread.
Attachments
In conduit, under concrete. Way before the S was a gleam in my eye, we decided to go crazy with backyard landscaping, including sidewalks, decks, concrete ponds, etc. I pretty much covered my garage feed in the worst possible fashion.
beeeerock
Active Member
Well if your definition of conduit is the same as mine (small diameter solvent weld Rigid PVC pipe, such as used for underground telephone, cable, fiber power etc.), just pull bigger conductors through the PVC. Or is your definition different?
beeeerock
Active Member
Well, an electrical contractor familiar with street light installations, underground hydro/tel/cable, etc. would either pull new wires with the old, or remove the old and suck through a pull string to get the new conductors in place. I thought you were stuck to dig up all the concrete...! Putting the duct in was the smart thing to do - this might not be as bad as you think.
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