48 amps or 72 Amps... Why should I get either?

[mzpolo]

OK. I am a Naval Architect, not an Electrical engineer.
Besides the obvious... "72 Amp charger can get you to charge faster", why do I need a 72 Amp charger?
Why does Tesla say that 110 and 220 charge times wont change? Is that because I wont pull more than 48 amps off the basic home electrical setup?

Can I even get that many amps out of a residential setup?
If the normal residential setup is limited, is the typical destination charger at restaurants, hotels, etc, high amperage?

I don't have a whole lot of options in the Norfolk VA area. I will install a home charger.

Any advice is very much welcome!

 

[Evbwcaer]

Most newer houses have 72/90 amps of unused capacity. (you would need a breaker around 90 amps to deliver a continuous load of 72 amps). The 220 times will change if the charger you are using is 72 amps vs. some lower amperage. Currently, most AC chargers out there are 30 or 40 amps. 72 amps may be more about utilizing charging options that are yet to come, but you can check plugshare.com and look for 80 amp J1772s in your area. Besides the Tesla HPWC and a Clipper Creek offering, I don't think there are many AC options that are capable of delivering more than 40ish amps.

One concrete reason to get the 72 amp option is if the area you live in offers time of use electrical billing with a time window too small to get the charge you need at 48 amps on a routing basis.

 

[stevezzzz]

Home charging is typically done by installing a NEMA 14-50 socket on a 240V/50A circuit; by code, you can only pull 40A continuous on that 50A circuit. For most people, an overnight charge at 40A is all they ever need for their daily driving.

Road trips where there are few Superchargers along the way (but with good availability of 80A Level 2 charging locations) are the best use case for dual chargers (in the Model S) or the 72A charger option in the X. If RV parks are your best charging option, you'll still be limited to 40A charging at the source and the 72A charger won't do you any good.

 

[KJD]

OK. I am a Naval Architect, not an Electrical engineer.
Besides the obvious... "72 Amp charger can get you to charge faster", why do I need a 72 Amp charger?
Why does Tesla say that 110 and 220 charge times wont change? Is that because I wont pull more than 48 amps off the basic home electrical setup?

Can I even get that many amps out of a residential setup?
If the normal residential setup is limited, is the typical destination charger at restaurants, hotels, etc, high amperage?

I don't have a whole lot of options in the Norfolk VA area. I will install a home charger.

Any advice is very much welcome!

Most of the public charging stations around here are only 30 amp.

The Tesla Superchargers bypass the on board charger, so it makes no difference when supercharging.

If you are plugged into a Tesla HPWC ( High Powered Wall Charger ) on a 100 amp breaker then you can draw 72 amps.

Can your residential system provide that much power is an open question. Some can and some are not even close.

There is a great FAQ written by FlasherZ that will answer your question in great detail.
FAQ: Home Tesla charging infrastructure QA

 

[Larry Chanin]

OK. I am a Naval Architect, not an Electrical engineer.
Besides the obvious... "72 Amp charger can get you to charge faster", why do I need a 72 Amp charger?
Why does Tesla say that 110 and 220 charge times wont change? Is that because I wont pull more than 48 amps off the basic home electrical setup?

Can I even get that many amps out of a residential setup?
If the normal residential setup is limited, is the typical destination charger at restaurants, hotels, etc, high amperage?

I don't have a whole lot of options in the Norfolk VA area. I will install a home charger.

Any advice is very much welcome!

To answer your question we have to be able to predict the future. However, we have some points that Elon and Tesla have made to guide us. In a few years they tell us that the number of Teslas added to the roads will increase by over an order of magnitude, year after year. The questions is will Tesla be able to keep up with Supercharger expansion to deal with that influx of new Teslas? If Superchargers become congested destination chargers will take on added significance.

Earlier this year Elon stated at a press conference that the number of destination chargers would in the long-term be 10 times the number of Superchargers. Obviously, Tesla is hedging their bets by offering alternative to Supercharging. I assume they have a reason for that.

Unless you are a "road warrior" you probably don't have to install a full capacity HPWC at home although in most modern homes you probably could. However, I see spending the $1000 to upgrade to a 72 amp on-board charger as a prudent insurance policy that will permit you to charge at destination chargers 50% faster than the speed of the default 48 amp. If you are in line behind a number of other Teslas, even it you choose not to upgrade to the high capacity on-board charger, you will be very happy if the cars in line ahead of you charge 50% faster than your car. ;-)

Here in Florida the vast majority of existing destination chargers are near the full capacity of an HPWC. As others have suggested, perhaps it would be worth your while to research the situation in Virginia. (Click here to view the existing destination chargers in Virginia.) If you do that you will find all destination chargers in Virginia are at least 64 amps and most are 80 amps. So if you opt to go with the default charger you will not be able to benefit from that added capacity. Therefore, if you need a back up to Supercharging you would benefit by having a high capacity on-board charger.

Larry

 

[Cosmacelf]

The vast majority of people do not need nor will ever find a use for the 72 amp charger. Chances are if you don't know you want one, then you'll never need one.

 

[SW2Fiddler]

If the normal residential setup is limited, is the typical destination charger at restaurants, hotels, etc, high amperage?

Yes - the typical Tesla Destination Charger is high amperage.

The main downside you will hear about EVs (from reasonable folks) is long charging time. I can't see not wanting to minimize the car's Achilles Heel as much as possible. My advice is to order high amp.

Chances are if you don't know you want one, then you'll never need one.

From reading people's stories here, I'd say chances are good for driving more than before, and driving more places than planned.

 

[MikeL]

Lots of good answers. I will get 72A capability for my Model X simply because I'd rather have it than wish I did. Look up Hwy 12 in southern Utah. I highly recommend it to All ! If there's a high Amp charger in Boulder or Escalante, I have the option to be there for lunch, as opposed to most of a day. Then head up to the Richfield SuperCharger or down the Burr Trail toward ... ? Utah has well placed SuperChargers, but it's also a very big place.

I will also go to some expense to get my old house up to modern electrical code. Which means 200A required for an old LEAF, a new Tesla, and the rest of that stuff in the house :smile:

 

[mzpolo]

Thanks all for the info. I think the consensus is that it is prudent to spend the money and get the 72A charger even if the every day home charge may not be to that level.
My personal situation, as with anyone with Dominion Virginia Power, stinks. I have a 5Kw PV solar array and if I want to get anything out of that, I have to either net meter or second meter. Both take away the ability to use the option of timing electrical use.
thanks for the info folks! Great help as always!

 

[MorrisonHiker]

However, I see spending the $1000 to upgrade to a 72 amp on-board charger as a prudent insurance policy that will permit you to charge at destination chargers at almost twice the speed of the default 48 amp. If you are in line behind a number of other Teslas, even it you choose not to upgrade to the high capacity on-board charger, you will be very happy if the cars in line ahead of you charge almost twice as fast as your car. ;-)

Just a slight correction: 72 amps is only 24 amps more than 48 amps...so that would be a 50% increase. It would definitely be faster, but not "almost twice the speed".

 

[vandacca]

If the destination chargers get too popular and line-ups form, the owners of these chargers may put time-limits on them (e.g. only 2 hours per vehicle) to make it fair for everyone. Having a 72A charger would maximize your charge in that given window.

 

[Zaxxon]

<snark> I'll answer the question that was actually asked in the thread subject line--because if you don't get either, you won't be able to charge at home or at destination chargers. You really limit yourself if you can charge only via DC. </snark>

 

[Larry Chanin]

Just a slight correction: 72 amps is only 24 amps more than 48 amps...so that would be a 50% increase. It would definitely be faster, but not "almost twice the speed".

Thanks for the correction. I've edited my posting in the interest of accuracy.

Larry

 

[Lyon]

You can certainly set up your home charging to allow for 72amp charging. At a minimum this requires the installation of a Tesla HPWC (or similar EVSE). Most people find the installation of a NEMA 14-50 outlet to be less expensive and less likely to require upgrading their electrical service. The Mode X comes with a UMC (universal mobile connector) that will plug the car into the NEMA 14-50 outlet. That will allow charging at 40 amps.

I am getting the 72amp because it's included in the Signature edition cars. I would have gotten it as an add on anyway because it's not upgradable later and because I travel in areas with limited Supercharging but some access to high amp level 2 charging.

Unless you've got a very specific use case you'll not need the higher rate of charge at home. The upgraded system is more likely to be used away from home.

 

[jerry33]

Unless you've got a very specific use case you'll not need the higher rate of charge at home. The upgraded system is more likely to be used away from home.

Destination chargers are often 80 amp HPWCs, as are many PlugShare entries. I've found it well worthwhile to have twin chargers in my Model S. At home I have a 14-50 with a Clipper Creek 32amp UVSE as a backup.

 

[Lyon]

Destination chargers are often 80 amp HPWCs, as are many PlugShare entries. I've found it well worthwhile to have twin chargers in my Model S. At home I have a 14-50 with a Clipper Creek 32amp UVSE as a backup.

I'm similarly situated. I've got dual chargers and, at least until about three weeks ago, I only had a NEMA 14-50 at home. In preparation for the Model X, I had a HPWC installed on the outside of the house. It turns out I had the excess capacity to run the 100amp circuit so I did it. I doubt I'll need it often.

The vacation home will have a 100amp HPWC and I will really like having it from time to time.

 

[Noone]

If you're in a hurry, 72A makes no difference; you need CHAdeMO or better a supercharger. If you are charging over night, 48A is plenty

 

[WarpedOne]

Common sense... very rare animal this days.

 

[TexasEV]

If you're in a hurry, 72A makes no difference; you need CHAdeMO or better a supercharger. If you are charging over night, 48A is plenty

Apparently you haven't read all the use cases described here why the capability for 72A charging is important for some people, but since you cancelled your Model X reservation I guess that wasn't important to you.

 

[Lloyd]

Put it this way. When your Mother in Law comes over to visit and charge......... Do you want her to stay for 2 hours or 4 hours!:scared: