Question about uprgrading 30A circuit

[rcsting]

I am upgrading from my Rav 4 EV to a Model S and have a quick question. My previous EVSE was a 30 Amp circuit ( NEMA 6-50 ) with 40 Amp breakers. Since the Model S comes standard with a 48 Amp charger should I have my electrician upgrade it to 60 Amp breakers or 50 Amp breakers? ( NEMA 14-50 )

I searched but didn't find the answer. Thanks for any assistance

Model S comes standard with a 48 amp onboard charger that provides up to 34 miles of range for each hour of charge. This is sufficient to recharge Model S overnight when connected to a common NEMA 14-50 outlet

 

[ABCCBA]

@rcsting my opinion is that you should upgrade to the largest circuit, up to 100 A that your panel can allow. Reason, as you have seen moving from one BEV to another, the battery technology is getting larger over time, thus to charge larger battery packs in a reasonable period of time, you will need higher Wattage. To get higher wattage, you have to increase Voltage, Current or Both. In the case of a residential home, 240VAC is typically the highest voltage you will have because of the service drop. So, the only real choice is higher current. So, by installing the largest rated conductors in your panel now, you will save a lot of money down the road as you chase the current levels higher and higher by having to ever change the size of the conductors. So, congrats on the Model S. Add a 80A or 100A circuit and a HPWC and have a simple and semi-future proof solution for years to come. JMHO

 

[RandyS]

Upgrading a circuit can sometimes be done, but the size of the wire is also an important consideration that you need to look at as well. In essence, the breaker is protecting the wire. So you don't want to just install a larger breaker without knowing if the wire size can handle the additional current as well....

The question about whether you really need to upgrade is probably dictated by how many miles you drive per day, how fast you want to recharge the battery, if there is a TOU window you're trying to hit, etc. Many people are okay with less charging current and it works for them.

 

[TexasEV]

A 50A circuit ( 50A breaker, 14-50 outlet) will give 29 miles of range per hour of charging. That's fast enough to charge overnight. Unless you need faster charging than that at home, there is no need to go to the additional expense of a higher amp circuit with the HPWC ( wall connector). The benefit of higher amp charging is primarily when you're traveling.

 

[davewill]

To be honest, the existing 40a circuit is enough to charge overnight.

 

[TexasEV]

But you can't plug into it natively with the UMC.

 

[ABCCBA]

But you can't plug into it natively with the UMC.

How about this $55 solution for the 6-50 circuit? NEMA 14-50R to 6-50P Adapter

 

[TexasEV]

How about this $55 solution for the 6-50 circuit? NEMA 14-50R to 6-50P Adapter

The car will see it as a 14-50 and set the charge for 40A. You would have to dial down the amps manually to 30A. That's the problem with using non-native adapters with a circuit of different amps than it's intended for. Yes that adapter would be good for rare use in an emergency, but it's not safe to depend on for daily use as the car sometimes forgets the lower amp setting (as has been discussed many times in other similar threads).

 

[AndreSF]

I would not change anything, to be honest... You have an existing EVSE (you did not mention which device, but I would guess it's at least 6Kwh system), just use J1772 adapter and call it a day. Under most "normal" driving routines, you will recharge overnight.

 

[davewill]

But you can't plug into it natively with the UMC.

But he already has a perfectly good EVSE.

 

[Galve2000]

I agree that there is really no reason to upgrade everything. IMO the world is moving to Level 3 charging... (level 2 is just too slow...)

so your existing 6.6 kW EVSE, while not as fast as 9.6 kW from the original Model S onboard charger, or 11 kW from the new 48 amp chargers, it really is in the same ballpark and any of the above will suffice for overnight charging. your money is better spent on a ChAdeMo adapter which will give you a charging rate (better than) twice as fast as an 80 amp Level 2 charger.

just my $0.02 worth...

 

[linkster]

I would not change anything, to be honest... You have an existing EVSE (you did not mention which device, but I would guess it's at least 6Kwh system), just use J1772 adapter and call it a day. Under most "normal" driving routines, you will recharge overnight.

Yup! Why unnecessarily spend more $? You'll achieve a 21-22mph charge rate at 30A and be able to keep your UMC stowed in the S for trips.

I have been charging on a UMC 14-30 (24A, 18mph charge rate) for over 3 years/62,000 miles with 80 and 160-mile commutes. Many folks around here feel that you must charge at 40, 48, 72, or 80 at home.

Congrats on your new S!

 

[tga]

Yup! Why unnecessarily spend more $? You'll achieve a 21-22mph charge rate at 30A and be able to keep your UMC stowed in the S for trips

Maybe consider getting another J1772 adapter ($95) to keep at home on the EVSE and keep on in the car (so you won't forget to take it for charging in the wild).

 

[jerry33]

I'd keep the current setup and upgrade later if there are too many times when a charge isn't completed overnight. However, unless driving patterns change, if it was good enough with the previous vehicle, it will be fine for the Tesla. The only inconvenience is that you'll need to use the adapter. I'd get a second J1772 adapter to keep in the vehicle and keep that one in the car so that there is one always connected to your EVSE.

 

[BriansBucketList]

I I bought a 29 dollar RV outlet NEMA 4-50 and ran NM 6/3 with 10ga ground, and my 70D charges at 30 amps on a 50 amp breaker. All wiring is cool during charging, but the UMC cable gets a little warm. I like the idea of planning for more current, but this setup charges well overnight. Bottom line, ask qualified electricity on, but I used 50 amp breaker, 6/3 with ground (40 foot run from 200 amp main) and an RV box. The UMC plugs right in. It cost me about 100 bucks, but I spent a lot of time with strain relief, bushings, etc.

 

[davewill]

... so your existing 6.6 kW EVSE, while not as fast as 9.6 kW from the original Model S onboard charger, or 11 kW from the new 48 amp chargers, it really is in the same ballpark ...

Especially since by the math you used on the other two, the 30a EVSE is actually 7.2kW,

 

[Galve2000]

Especially since by the math you used on the other two, the 30a EVSE is actually 7.2kW,

I stand corrected. Apologies.

 

[Boatguy]

The very first thing to do is to have a licensed electrical contractor determine the size of the wire feeding your current EVSE. Maxing out the circuit breaker and changing the outlet to utilize the wire you have should both be very inexpensive.

If it's already maxed out at 30a, then as others suggest, buy another J1772 adapter and use your current EVSE for 3-4 months to see if you really have any problems getting fully charged overnight.

I would not spend the $1,500 + to upgrade the circuit and and buy/install an HPWC until you are certain you need it. You may find that 99% of the time that 24mph of charging is enough. Depending on your driving plans, the money might better be spent to upgrade to the 78a onboard charger which is more useful at destination charging stations, or spent on something else entirely.