Home Charging Time for i7?

[DroMike]

PLEASE FOLLOW THIS PARA BY PARA TO GET TO QUESTION AT BOTTOM:

For my upcoming i7, I've contracted for a dedicated outlet/circuit in my garage, to be installed in the next week or two. Accordingly, I went:

FROM (considering): an existing 240v dryer outlet on 30 amp circuit
TO (be installed): a 240v outlet on a dedicated 40 amp circuit.

I'd LIKE to know is how much faster would my 20-80% charging time now be. However, I keep hearing that an amp circuit can only charge 80% of its amperage (ergo, the 30 amp would be 24 amps, and the 40 amp would be 32 amps). I simply don't know which figure to use (higher or smaller).

I DID find this "Charging Time Calculator" but it requires one to know one's "Charging Time in kW" to make it work. https://www.homechargingstations.com...charging-time/

Happily, I also found an easy formula for kW: (Amperage x Voltage) / 1000

That said, I BELIEVE:

24 x 240 = 5,760 / 1000 = 5.76 kW [dryer, 24 amps]
30 x 240 = 7,200 / 1000 = 7.20 kW [dryer, 30 amps]
32 x 240 = 7,680 / 1000 = 7.68 kW [dedicated outlet, 32 amps]
40 x 240 = 9,600 / 1000 = 9.60 kW [dedicated outlet, 40 amps]

Thus using the "Charging Time Calculator," the actual charging time (going from 20-80% charged) would take:

12 hrs, 16 min (at 5.76 kW) [dryer, 24 amps]
9 hrs, 48 min (at 7.20 kW) [dryer 30 amps]
9 hrs, 12 min (at 7.68 kW) [dedicated outlet, 32 amps]
7 hrs, 21 min (at 9.60 kW) [dedicated outlet, 40 amps]

My QUESTION is, which actual charging time would I have got from the dryer outlet and which actual charging time will I get from the dedicated outlet?.

[evanevery]

1. You won't get full 30A charging from a "30A" drier outlet...

For example, in order to get 40A (9.6KW) charging, you actually need a 50A circuit. (Based on efficiencies, mfr recommendations, and safety) If you want a full 50A charge, then a 70A circuit is typically specified... (Both my charger outlets are on 50A circuits, so I am configured for 40A or 9.6 KW each...) Charger Manufacturers typically specify this very clearly in their manuals...

No one really specs out a 30A circuit for a fixed EV charger (although many "portable" chargers will work with one...) As such, I'm unsure of what amperage you would have to limit the charger to. Maybe 25A? (about 6.0KW) You would need to check with the configurable options available for the specific charger you plan on using. ...but it would be less than 30A.

2. The i7 M70 has a battery size of 105.7KW. If you wanted to fully charge a completely drained battery, you BASICALLY divide the battery size by the charger output. I.E 105.7/9.6 (40A) = 11 Hrs 105.7/6.0 (25A) = 17.6 Hrs

3. Not necessarily a meaningful concern for level 2 home charging, but EV's will accept higher charging rates ONLY when close to empty. As the battery charge increases, the charging rate decreases. (IOW: a 350KW Electrify America charger is not going to provide a linear 350 KW charge - even if the car could accept it. Charging tapers off as the battery fills up...) Aagin, not so relevant for home charging...

4. All that being said, no one completely uses their entire battery capacity every day. If you do, then an EV was a bad choice. You will only need to charge up based on what you have actually used...

5. ...and you don't typically charge an EV to 100% every day. Only when you know you have a long trip planned. Most EV suggest a lower charge for daily use. BMW recommends 80% daily charging (on my iXM60), Porsche recommends 85% (on my Taycan Turbo S). You don't really want to charge to 100% every day as it places needless strain on the battery. Only charge to 100% when you really need it!

So all that being said, the typical usage model for EV's with home chargers is simply plug it in when you get home and it should be ready to go (at 80-85%) in the morning. (Like your cell phone). If you have greater range/charging demands then that, then an EV may not be a great choice...

Hope this helps...

[DroMike]

Thanks for your thoughtful reply Evan. I guess I really only needed corroboration that my 40A circuit would actually charge at just 32A (instead of the full 40A).

And yes, I'm only talking about charging from 20% to 80% capacity -- I already know not to charge fully to 100% unless taking a rare long trip.

Accordingly, I'm happy enough that we were able to pinpoint it'd then take approximately 9 hrs, 12 mins indicated per the "Charger Time Calculator" times shown -- more or less overnight as you point out.

[CaboM4]

Originally Posted by evanevery

1. You won't get full 30A charging from a "30A" drier outlet...

For example, in order to get 40A (9.6KW) charging, you actually need a 50A circuit. (Based on efficiencies, mfr recommendations, and safety) If you want a full 50A charge, then a 70A circuit is typically specified... (Both my charger outlets are on 50A circuits, so I am configured for 40A or 9.6 KW each...) Charger Manufacturers typically specify this very clearly in their manuals...

No one really specs out a 30A circuit for a fixed EV charger (although many "portable" chargers will work with one...) As such, I'm unsure of what amperage you would have to limit the charger to. Maybe 25A? (about 6.0KW) You would need to check with the configurable options available for the specific charger you plan on using. ...but it would be less than 30A.

2. The i7 M70 has a battery size of 105.7KW. If you wanted to fully charge a completely drained battery, you BASICALLY divide the battery size by the charger output. I.E 105.7/9.6 (40A) = 11 Hrs 105.7/6.0 (25A) = 17.6 Hrs

3. Not necessarily a meaningful concern for level 2 home charging, but EV's will accept higher charging rates ONLY when close to empty. As the battery charge increases, the charging rate decreases. (IOW: a 350KW Electrify America charger is not going to provide a linear 350 KW charge - even if the car could accept it. Charging tapers off as the battery fills up...) Aagin, not so relevant for home charging...

4. All that being said, no one completely uses their entire battery capacity every day. If you do, then an EV was a bad choice. You will only need to charge up based on what you have actually used...

5. ...and you don't typically charge an EV to 100% every day. Only when you know you have a long trip planned. Most EV suggest a lower charge for daily use. BMW recommends 80% daily charging (on my iXM60), Porsche recommends 85% (on my Taycan Turbo S). You don't really want to charge to 100% every day as it places needless strain on the battery. Only charge to 100% when you really need it!

So all that being said, the typical usage model for EV's with home chargers is simply plug it in when you get home and it should be ready to go (at 80-85%) in the morning. (Like your cell phone). If you have greater range/charging demands then that, then an EV may not be a great choice...

Hope this helps...

This is 100% spot on! You couldn’t ask for a better, more accurate response

[rollingtaser]

Originally Posted by evanevery

1. You won't get full 30A charging from a "30A" drier outlet...

For example, in order to get 40A (9.6KW) charging, you actually need a 50A circuit. (Based on efficiencies, mfr recommendations, and safety) If you want a full 50A charge, then a 70A circuit is typically specified... (Both my charger outlets are on 50A circuits, so I am configured for 40A or 9.6 KW each...) Charger Manufacturers typically specify this very clearly in their manuals...

No one really specs out a 30A circuit for a fixed EV charger (although many "portable" chargers will work with one...) As such, I'm unsure of what amperage you would have to limit the charger to. Maybe 25A? (about 6.0KW) You would need to check with the configurable options available for the specific charger you plan on using. ...but it would be less than 30A.

2. The i7 M70 has a battery size of 105.7KW. If you wanted to fully charge a completely drained battery, you BASICALLY divide the battery size by the charger output. I.E 105.7/9.6 (40A) = 11 Hrs 105.7/6.0 (25A) = 17.6 Hrs

3. Not necessarily a meaningful concern for level 2 home charging, but EV's will accept higher charging rates ONLY when close to empty. As the battery charge increases, the charging rate decreases. (IOW: a 350KW Electrify America charger is not going to provide a linear 350 KW charge - even if the car could accept it. Charging tapers off as the battery fills up...) Aagin, not so relevant for home charging...

4. All that being said, no one completely uses their entire battery capacity every day. If you do, then an EV was a bad choice. You will only need to charge up based on what you have actually used...

5. ...and you don't typically charge an EV to 100% every day. Only when you know you have a long trip planned. Most EV suggest a lower charge for daily use. BMW recommends 80% daily charging (on my iXM60), Porsche recommends 85% (on my Taycan Turbo S). You don't really want to charge to 100% every day as it places needless strain on the battery. Only charge to 100% when you really need it!

So all that being said, the typical usage model for EV's with home chargers is simply plug it in when you get home and it should be ready to go (at 80-85%) in the morning. (Like your cell phone). If you have greater range/charging demands then that, then an EV may not be a great choice...

Hope this helps...

i second that, best answer possible!

DroMike
about charging: check this out:
https://evkx.net/models/bmw/i7/i7_xd...chargingcurve/
it might help you in understanding how charging works in general