I took delivery of my new Model S Plaid last week. I accidentally plugged it into my 40 amp charger that I had installed when I bought my 2014 Model S. It appeared to run at 40 amps without any issues. I had assumed that the car would limit the charge to 32 amps, but it ran at 40. Are there any potential problems using the 40 amp charging with a new Model S?
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Any issues when using an old 40 amp home charger with a 2023 Model S ?
- Thread starter kWh
- Start date
Nope. Model s can charge up to 48 amps. Why would there be any issues?
These systems kind of run on a "lowest common denominator" operating philosophy. The external charging device will announce to the car how much it has available (40A). And then the car will see that and say, "Oh, I can use up to 48A, so yes, I can use all of that 40A." and it will request 40A. No issues with mixing and matching whichever kind of Tesla plugs with other Tesla cars.
E90alex
Active Member
Same for J1772 plugs/cars and J1772 with Tesla adapters and vice versa.
Or basically any device that charges. It’s made to be essentially foolproof.
While my old Juicebox EVSE and plug can handle 40A, I usually dial it back to 24-30A for regular overnight charging or up to 36A when I need a faster rate during the daytime. I've noticed the cord near the plug (wand) gets pretty warm above 34A hence my habit of dialing it back. My electrical line, receptacle, circuit, and sub-panel was all installed when I had my rooftop solar array installed back in 2016 and was permitted and inspected by my city. I have confidence in it but again, I'm not comfortable with the heat.
aerodyne
2 of 3 EV's - Defect Free!
Rocketfan30
Member
My old Juicebox plugged into a dryer port that I used for years for a PHEV Ford Fusion and Honda Clarity before my 2021 Model S melted after about a year of charging my Model S. Well the connector to the Juicebox melted and the dryer plug melted. When I called out our regular electrician to fix the plug and make sure everything else was ok, he said he has seen a lot of melted plugs with Teslas.
I assume this is why the Gen 2 Mobile Connector which I use now limits charge to 32 amps but who knows. Does anyone know the reason they did this? I am just thankful my house didn't burn down and all I got was a slightly smoky garage.
islandbayy
Active Member
There were some problems starting in 2018 with 2018 & newer Model S and X vehicles not working with Gen 1 HPWC's, yet M3's and MX's worked fine. I have not yet tried it on the newer redesign cars yet though.
Originally found this issue as we were getting guests at our Resort who couldn't charge on our Gen 1 HPWC yet both my 2016's worked fine. We added a Gen 3 HPWC, which works fine thus far for everyone.
Originally found this issue as we were getting guests at our Resort who couldn't charge on our Gen 1 HPWC yet both my 2016's worked fine. We added a Gen 3 HPWC, which works fine thus far for everyone.
Plugs to other plugs to other additional plugs is starting to chain together a lot of weak connections. That's why it can get iffy to use extension cords for high current constant loads. Electric code won't even allow any plug and cord connections for anything over 60A. Hard wired, screwed in connections are tighter and more surface area connections.
I don't think it's that reason, but is probably a different one. NEC allows 50A receptacle types on 40A circuits. These are commonly put in for ovens. So with a lot of these out there, people might plug into them, and the EV charging devices might attempt to draw a constant 40A from them, when they shouldn't. So I think Tesla was playing it safe to avoid problems with outlets like that.
vcor
Tech Specialist
I'll add that if you have aluminum wiring, that is often installed improperly and can cause overheating problems at the connections. Tesla Wall units are only rated for using copper wires. Tesla even puts a thermal sensor on the connection to protect against bad installations and will shut down if high temperatures are detected. Most non-Tesla EVSE equipment has no such monitoring and will let the wiring burn up if not attached properly - no matter what brand of vehicle is attached. Tesla vehicles also monitor for voltage sag and will stop charging if detected. This is another indication of bad wiring or connections, but it may not be enough in every situation, and /or you could still get melting at poor connection points.
Anyway, when you're using high power (i..e 240 V at 24+ amps), you really should consider a dedicated line from the breaker box just for the EV without in-between connections. You also might consider using Tesla's WC, which is a lot safer than what you are using now. Yep, it is more expensive, but having your house burn down is expensive too!
Anyway, when you're using high power (i..e 240 V at 24+ amps), you really should consider a dedicated line from the breaker box just for the EV without in-between connections. You also might consider using Tesla's WC, which is a lot safer than what you are using now. Yep, it is more expensive, but having your house burn down is expensive too!
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