Some early Tesla Model S vehicles had a dual onboard charger option that
allowed up to 80 amps. Default option was a single 40 amp charger.

Later, as part of the first Model S refresh (2016), the charger design
changed and the maximum option was reduced to 72 amps, and default became
48 amps. Some Model X vehicles may also have the 72 amp upgrade.

Later still (~2018) the 72 amp option was removed from the menu, and ever
since Tesla vehicles have all maxed out with 48 amp onboard chargers (or
less on the most basic Model 3).

The Tesla portable EVSE has also shrunk from a Gen1 model at 40 amps to
Gen2 at 32 amps. The Gen1 makes for a compact portable high power EVSE.
Gen2 is still 'good enough' for most home charging.

I think the reduction in Tesla's onboard AC charging and portable EVSE
capability may be related to the growth of the Tesla Supercharger network.
It certainly has correlated with it. At a minimum it allows for fewer
product design and build variations, simplifying production, and making
available parts stretch further.

High power onboard charging is not always needed at home/work. Fast
home/work charging times/options are important especially when there is no
alternative way to fill up fast, and/or when you have vehicles with small
batteries. But with an expanded Supercharger network, the usual home/work
charging sessions can be at lower power, and additional unexpected local
charging requirements can be met via Superchargers.

One other thought: the lower power onboard chargers and EVSEs may help
Tesla tell utility companies they're taking steps to minimize peak loads on
residential electric grids.


As for circuits:
Per NEC loading limits, continuous duty circuits can only be loaded to 80%
of nameplate rating. This means:
100 amp circuit to serve 80 amp EVSE
60 amp circuit to serve 48 amp EVSE
50 amp circuit to serve 40 amp EVSE
40 amp circuit to serve 32 amp EVSE
30 amp circuit to serve 24 amp EVSE

For any given current, the voltage supplied also plays a role in charging
speed. The same equipment can run at higher power via a higher voltage.
EVSEs and onboard chargers are designed to support 240/208/120v AC inputs.
To tweak charging speed, use a supply voltage near the upper range of what
is in-spec as acceptable. An example is supplying a 250v AC vs 230v AC.
Both are in-spec for a nominal '240v AC' source.

At 72 amps:
250v gives us 18.000 kW
230v gives us 16.560 kW
208v gives us 14.976 kW

At 48 amps:
250v gives us 12.000 kW
230v gives us 11.040 kW
208v gives us 9.984 kW

208v is commonly seen on commercial electric services.

Here's a thread about charging at 250v:
https://teslamotorsclub.com/tmc/threads/charging-at-250v.218096/

If putting in a new circuit, a NEMA 14-50 supplied with 6 AWG copper is a
good all-around option, and gives you an outlet usable for other 50a
appliances like welders. If you want more headroom like for EVSEs that can
share a circuit, maybe aim for a 100a circuit using 1/0 compact aluminum
cable in 2" PVC conduit.

Smaller 1 1/4" conduit could work, but it's easier to pull through larger
conduit, and 2" is large enough to allow 2x 100a circuits, or other
combinations of changes or upgrades. If you're paying someone to install
for you, the labor cost won't be much or any different for a minimum
capacity conduit vs one that leaves some headroom.


On Tue, Nov 2, 2021, 17:20 Lawrence Rhodes via EV <[email protected]> wrote:

> Seems the new EVs with bigger capacity would benefit from an 80amp
> service. I am a fan of converting old Avcon EVSE to J1772.  Nothing more
> than a new connector. Could I just upgrade the wire and contactors in just
> about any EVSE to harden it for higher amperage?  Anybody done that yet?
> Lawrence Rhodes
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