Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Gen 3 Charger Power Sharing - who has this working?

davedesa

New Member
Oct 27, 2020
4
2
Boston
I just setup power sharing via subpanel and seems to be working okay. Noticed the following behavior and just wanted to see if others are seeing the same thing. Overall it appears to be working, but not quite the behavior I was expecting.
  • Wifi to home network is only on the master wall connector. The other one shows connected to my network, but doesn't have a local IP or shows up on my client list.
  • When both chargers are connected, even if only one is charging it defaults to 24A. Then it slowly ramps up the amps on the car that is charging. If just one charger is plugged in it will charge at 48A right away.
I'm experiencing the same situation. Not really what I expected. It's not ideal to have to unplug the other car to get the full 48amps. It's not a deal-breaker since I don't need the 48 amps in most cases, but I'm hoping Tesla fixes this.
 

miimura

Well-Known Member
Aug 21, 2013
6,695
6,538
Los Altos, CA
The lowest possible pilot signal for a J1772 compatible EVSE is 6A. I would expect that if a non-charging car is plugged in, that 6A must remain allocated to that plug. In theory, with a 60A breaker setting, the actively charging car should eventually have 42A available, even if it starts out at 24A and ramps up from there as indicated above.
 
  • Informative
Reactions: mociaf9 and Rocky_H

Sophias_dad

Active Member
Supporting Member
Jul 29, 2018
1,696
1,787
Massachusetts
I'm experiencing the same situation. Not really what I expected. It's not ideal to have to unplug the other car to get the full 48amps. It's not a deal-breaker since I don't need the 48 amps in most cases, but I'm hoping Tesla fixes this.
I'm not sure what you mean. "slowly ramps up the amps on the car that is charging" is presumably only tens of seconds or low-minutes. I don't think there's anything to fix.

I mean, lets suppose for a moment the rule is "When a car gets plugged in, it gets full power immediately, and over time we figure out how much the two cars together are using and turn them down appropriately." If you were to plug in two cars at the same time, they'd be drawing double the amount they were supposed to, at least for a time. In truth, since this is a Gen3 thing, you might be okay since they are supposed to have separate circuits at least back to a subpanel. If they are going back to a main panel(rated at 100A or better main breaker), it probably won't trip, since 48 extra amps for the tens of seconds it takes to ramp-down might not be enough to trip it. If they are instead going back to a subpanel specifically installed in the garage for charging, it might have only a 60 amp feed breaker coming to it, and that feed breaker may trip because the charge level isn't curtailed fast enough.

When the other choice is "wait (literally) a minute to get up to full current levels", that's really easy to decide, since a typical charging session is hours long.
 

davedesa

New Member
Oct 27, 2020
4
2
Boston
I'm not sure what you mean. "slowly ramps up the amps on the car that is charging" is presumably only tens of seconds or low-minutes. I don't think there's anything to fix.

I mean, lets suppose for a moment the rule is "When a car gets plugged in, it gets full power immediately, and over time we figure out how much the two cars together are using and turn them down appropriately." If you were to plug in two cars at the same time, they'd be drawing double the amount they were supposed to, at least for a time. In truth, since this is a Gen3 thing, you might be okay since they are supposed to have separate circuits at least back to a subpanel. If they are going back to a main panel(rated at 100A or better main breaker), it probably won't trip, since 48 extra amps for the tens of seconds it takes to ramp-down might not be enough to trip it. If they are instead going back to a subpanel specifically installed in the garage for charging, it might have only a 60 amp feed breaker coming to it, and that feed breaker may trip because the charge level isn't curtailed fast enough.

When the other choice is "wait (literally) a minute to get up to full current levels", that's really easy to decide, since a typical charging session is hours long.
I agreed, a few-minute ramp would be excellent, but it's closer to hours and never reached 48amps. The max I was able to see is 40amps after multiple hours. On the other hand, my Gen 2 setup would take a few seconds.
 

tm1v2

Member
Oct 18, 2021
256
172
USA
I agreed, a few-minute ramp would be excellent, but it's closer to hours and never reached 48amps. The max I was able to see is 40amps after multiple hours. On the other hand, my Gen 2 setup would take a few seconds.
If you can find a way to report this to Tesla, please do! I might deploy a power sharing setup soon, and while this behavior wouldn't be a deal-breaker, would be nice to have a quicker ramp.

I assume the charging protocol lets it ramp a car back down, if another car starts requesting more...
 

Sophias_dad

Active Member
Supporting Member
Jul 29, 2018
1,696
1,787
Massachusetts
I agreed, a few-minute ramp would be excellent, but it's closer to hours and never reached 48amps. The max I was able to see is 40amps after multiple hours. On the other hand, my Gen 2 setup would take a few seconds.
I agree that that sounds like defective charging behavior. I'd definitely report it to Tesla.
 

Products we're discussing on TMC...

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top