# Forums

## Charging Time

I find the charging information not very helpful enough. What I would like to know is how long it would likely take me to fully charge a battery set of a model S that had (a) 50% of a full charge and (b) 20% of a full charge at the start of recharging. The equipment I am considering would be a 240 volt 20 amp NEMA 14-50 plug system that I would install in my garage.

On this subject generally, this link http://www.rapidtables.com/convert/electric/kw-to-va.htm has a power factor for converting Kw to Volt-Amps. Does any one know what the typical power factor for the Tesla power supply is?

ghillair | 13 mars 2014

First the NEMA 14-50 is designed to be installed on a 50 amp breaker. I don't think it meets code to use a 20 amp breaker.

On a 50 amp circuit you charge at 40 amps, you can only draw 80% of rated for prolonged periods. At 40 amps you get about 28 miles of charge per hour. If you are talking an 85 full charge is 265 rated miles so that is about 10% per hour. If you are talking about a 60 it is still 28 mi/hr but the total time is less.

If you only have a 20 amp circuit you need a different plug with an adapter. Your charge rate will be about 11 miles per hour.

EQC | 14 mars 2014

great info and explanation, ghillair.

2Cybers: you can find Tesla's official explanation here, with charging rates for additional types of plugs too:

http://www.teslamotors.com/charging#/outlet

Hit the link, then hit the "right" arrow once to select the "Adapter Guide" heading. You should then see a list of plugs, the power each can put out to charge a Tesla, and the effective charge rate in miles per hour.

If you plan to drive, say, 100 miles per day, and you have a plug that can push power to the car at 29 miles per hour, then you can replenish your battery in a about 3.5 hours (100 miles, divided by 29 miles per hour, equals 3.45 hours).

For your specific questions, recharging 50% of an 85 kWh battery is about 140 miles worth of charge...that would take about 5 hours at 29 miles of charge per hour. Filling 80% of the same battery would be about 215 miles worth, and take about 7.5 hours.

As the previous post mentioned, do NOT hook up a 14-50 plug (intended to draw 50 amps) on a 20 amp circuit...that is against code and a problem waiting to happen.

Bikezion | 14 mars 2014

And by "a problem waiting to happen" EQC means FIRE! And the Darwin of the year award.

EQC | 14 mars 2014

And by "FIRE!" Bikezion means in the outlet box and/or inside the walls of your house. The fire would be entirely due to the faulty wiring catching itself on fire; the fire could not and should not be blamed on Tesla in any way. The car would probably be undamaged until the electrical house fire expanded to engulf the car (and any other car in the garage) or the house burned down and collapsed on the Model S.

Of course, the media might put a different, sensational spin on the story...