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Charging at 48A?
- Thread starter Gellie
- Start date
EVs are considered continuous loads, and are only allowed to take 80% of the circuit's rating.
AND
The onboard charging circuitry in the battery assembly can only convert 48 amps(on a long-range model) or 32 amps (on a short range model).
AND
The onboard charging circuitry in the battery assembly can only convert 48 amps(on a long-range model) or 32 amps (on a short range model).
Sacramento
2021 Tesla Model Y LR AWD
80% of 60 amps is 48 amps...you need the 60 amp breaker for sustained 48 amp charging.
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angus[Y]oung
Active Member
@Gellie yep, you are charging as fast as you possibly can outside using a DC fast charger (Tesla Supercharger, or another DCFS with Chademo or CCS adapter)
TomServo
Active Member
36 mph on my 40 amp Clipper Creek. What a difference voltage makes.
Yup, I am on a 32 amp ChargePoint home L2 and I usually get 33 amps (bonus!) and around 245 volts giving me 8 KW. Always sad when I charge on a public charger that is on a 3 phase setup, running 208 or less volts.
Keith
Hi folks; so I've joined "the club" and have my first Y-P sitting in my garage. It's on an [electrician installed] ClipperCreek HCS80 (80A rating so 64A/15.4kW max flow) and connected to the Y using a J1772 adapter. The dashboard shows it's getting 48A (which I believe is the maximum), so no surprise there...but why am I seeing 39mi/hr vs. advertised 44mi/hr? Both the CC website claim 44, and a friend of mine with his Tesla wall unit sees 44mi/hr at 48A. Obviously it's not a huge diff, but curious why the 10% less flow rate and is there some setting I need to adjust in the car? (there are none I'm aware of on the HCS80)
The speed at which you can charge the battery will slow as the battery state of charge increases. Expect the fastest charging from 10% (or less) to 40%, then from 40% to 70%, with much slower charging from 70% to 100%. You will see this when Supercharging too but it is more noticeable because when Supercharging the maximum power provided to the Tesla vehicle will be tapering and the charging speed is also slowing at the same time.
Since we’re on the subject, I typically don’t run my garage charger at full 80% of rating, usually throttle it down to 32 (50A circuit). This is plenty fast enough for our driving. I Assumed this was better for the battery and less risk of catching my garage on fire. Am I being stupid?
TomServo
Active Member
Nope, if 32 amps meets yours needs there is ZERO reason to charge at a higher amperage. On the occasion when you need faster charging you can always bump it up. But at most you might save is an hour going up from 32 to 40, and from 40 to 48 amps. It’s really not that much of a gain when charging over night say. But bragging rights has its merits.
Charging at 32A instead of 40A is not "way better" for the battery. Even the maximum Level 2 (240V) charging rate for the Model Y of 48A (11.5kW) is no more than 1/7th of C (14% of C) where C is the capacity of the battery in kWh/1hr. An 82kWh battery can be charged at a rate of 80kW or less per hour without stressing the battery. As to whether the lower charging amperage (32A versus 40A) is better for the house wiring it would depend on the age of the wire, the type of wire and the highest temperature experienced while charging.
By lowering the charging level from 9.6kW to 7.7kW you are extending the time needed to charge by an equivalent amount of time (20%.) Although this can be measured in pennies per charge the faster you can complete charging the less total overhead (heat losses, conversion losses) will accrue. Faster charging will maximize your charging efficiency.
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Your voltage (232V) on that circuit is lower than their voltage. I bet your Neighbor shows over 240V.
Could be how far your EVSE is from the breaker panel, or maybe other loads (dryer?) or maybe the grid were reducing your overall house voltage.
Different time of day also results in different house voltage.
Remember V(volts) x A(amps) = W(watts) (or mph charge rate) W/1000 is kW.
increase the V or the A and get more W.
decrease the V or the A get less W.
The size (gauge) of the wire establishes the nominal electrical load (55amps let’s say) allowed on that circuit.
The circuit BREAKER establishes the maximum allowable electrical load (60amps let’s say) allowed on that circuit. It‘s just an overload protection switch that protects the wire (from a load that could overheat or burn the wire). It doesn’t “provide“ amps or volts or anything. You are protecting the appropriate gauge of wire with the appropriate breaker.
So yes, you needed the 60amp breaker to protect the specific wiring in your wall or conduit, and not limit the circuit below it’s capability.
The Tesla onboard charger is what demands an electrical load (48amps) on that circuit. To charge the battery.
The EVSE is just a safety handshake, coordinator between circuit and charger.
In a simplistic way……….Motors, chargers, bulbs etc. aren’t “given“ an electrical load, they ”demand” it. That demand is Amps.
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My MY takes the full 48 amps until it shows 100%, and for several minutes after that. If the heat pump isn't running, it'll show 43 to 45 MPH charge rate, with my voltage between 232 and 238.
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