2017 Model S 75D - Charging Amps Reduced

[Craig Vahle]

Just in the last week, I'm seeing the amps reduce when charging on AC. Charging on DC at a Supercharger is not effected and charges quite fast as you'd expect.

I noticed it first on my cousins J1772 Chargepoint charger. Its a 240V / 40 Amp charger. Car begins charging at this rate, but some time later, I'll check and its reduced consistently to 240V / 30A.

Then fast forward a few days. I'm back home using my Tesla wall charger. It starts out typical at 240V/ 48A. Then I'll check back and its 24A. I've never seen this at home and I've been using for several years now. I happen to have a second wall charger on the same circuit for my wife. It does the same thing now. The other car is not charging at the same time and nothing has changed at home.

I thought at first my cousins charger was the issue, but after coming home and now having similar issue at home, I'm convinced its the car. I've rebooted a few times. Any ideas?

 

[rog1206]

Did you get an update recently?

I also have a 17' 75D and this has happened to me several times. After manually increasing the amp to 40, the settings seem to stay for a while.

 

[hybridbear]

Just in the last week, I'm seeing the amps reduce when charging on AC. Charging on DC at a Supercharger is not effected and charges quite fast as you'd expect.

I noticed it first on my cousins J1772 Chargepoint charger. Its a 240V / 40 Amp charger. Car begins charging at this rate, but some time later, I'll check and its reduced consistently to 240V / 30A.

Then fast forward a few days. I'm back home using my Tesla wall charger. It starts out typical at 240V/ 48A. Then I'll check back and its 24A. I've never seen this at home and I've been using for several years now. I happen to have a second wall charger on the same circuit for my wife. It does the same thing now. The other car is not charging at the same time and nothing has changed at home.

I thought at first my cousins charger was the issue, but after coming home and now having similar issue at home, I'm convinced its the car. I've rebooted a few times. Any ideas?

When the car lowers the amps if you check the dash is there a message? I’d be particularly interested in seeing if there’s a message with the 40 to 30 amp reduction using the ChargePoint unit.

We have a ClipperCreek HCS-50 so we charge at 40 amps on a 50 amp circuit. The garage at our apartment has 3 phase power so it’s 208 volts, not 240. We see 196-198 volts under the 40 amp load in our Tesla app. About half the time the car will reduce the amperage to 30 while charging. Often it happens within the first 10 minutes of charging. But sometimes it happens later, even hours into the charge. The car displays a message about “poor grid quality” when it does this. We also sometimes plug in & the app shows 24 amps instead of 40 while in the “waiting to charge mode”. Even when it shows 24 amps while waiting to charge it still charges at 40 when charging starts.

We have almost never charged with a Tesla HPWC except maybe a few times while traveling so I wonder if somehow this behavior is related to using the J1772 adapter to charge.