Should I upgrade breakers/wiring for new 48 Amp Charger?

[ChrisJ]

I've yet to take delivery of my MS (due in the next two weeks) and I had scheduled the installation of a NEMA 14-50 for next week.

Tesla is still recommending a NEMA 14-50 outlet but I'm concerned about running it off of a 50AMP breaker and #6 wires as recommended if I plan on running it at the full 48 Amps. I know I can limit the car to a lower rate but it would be nice if it could use the full range.

Question is, should I bump the breaker to 60 Amp and use bigger wires (#4 instead of #6)?

Originally my electrician was going to use NM-B 6/3 which is rated at 55 Amp, but there's also #6 65 Amp THHN (multiple single wires).

There's a good chance I'll eventually replace the NEMA with a HPWC, so again it would be nice to run it at the highest capacity for the new 48 Amp onboard charger.

Thoughts?

 

[Saghost]

Well, if you're thinking you'll eventually want to run the highest capacity with an HPWC, maybe you should be thinking about wiring for 90 Amps - after all, Tesla is now saying the 48A chargers are all post delivery upgradeable to 72A...

Aside from the HPWC future, I don't think it matters - AFAIK the UMC is limited to 40A even if the car can take more and the outlet has more capacity.

 

[ChrisJ]

Thanks for the response.

Yep, 72A upgradeable charger confirmed in the refreshed models, but I should have added that I'm pretty sure I'll not upgrade.

I missed the UMC is limited to 40A, so it sounds like I have my answer - unless I decide to add a HPWC later. Can it set to somewhere between 40-48A?

 

[Amoroso6]

Thanks for the response.

Yep, 72A upgradeable charger confirmed in the refreshed models, but I should have added that I'm pretty sure I'll not upgrade.

I missed the UMC is limited to 40A, so it sounds like I have my answer - unless I decide to add a HPWC later. Can it set to somewhere between 40-48A?

If you are already using #6 wire then go with the 60 amp breaker which will allow you to charge a the Max 48 amps the standard charger will take.

 

[David99]

I'm always for planning higher than needed, just in case. And it sounds like you are actually going to want a HPWC. The cost difference for a 65 Amp breaker and the bigger wires is probably small so I would go ahead and do that.

Having said that, I drive a lot (30k-40k miles a year) and I'm totally fine with the 40 Amp UMC. I never wasn't able to charge as much as I wanted. There were a few situations where I would have a very quick charge, but even a 80 Amp dual charger would not have cut it. I have a CHADeMO at a mall near by. If I really need, that's still much faster even counting in the time to drive there.

 

[Saghost]

Thanks for the response.

Yep, 72A upgradeable charger confirmed in the refreshed models, but I should have added that I'm pretty sure I'll not upgrade.

I missed the UMC is limited to 40A, so it sounds like I have my answer - unless I decide to add a HPWC later. Can it set to somewhere between 40-48A?

I'm not sure I understand the question. The new HPWCs can set to 40, or to 48 (50A wire/breaker, 60A wire/breaker,) or to several levels above and below that. I don't believe there's a level between 40 and 48, however, if that was the question.

 

[davewill]

You can't use a 14-50 of you go over 50a on the breaker. You could oversize just the wire and change the breaker if and when you install your HPWC.

 

[ChrisJ]

I'm not sure I understand the question. The new HPWCs can set to 40, or to 48 (50A wire/breaker, 60A wire/breaker,) or to several levels above and below that. I don't believe there's a level between 40 and 48, however, if that was the question.

Sorry, I should have read the manual, I knew you could set various levels but wasn't sure if there was any steps between 40 and 48. Thanks for clear it up.

You can't use a 14-50 of you go over 50a on the breaker. You could oversize just the wire and change the breaker if and when you install your HPWC.

Thanks. That makes sense. I may add a sub-panel to allow me to add the HPWC later and go with the NEMA for now.

 

[Edmond]

Don't use a UMC at 40 amps, or you'll be sorry.

 

[swegman]

Don't use a UMC at 40 amps, or you'll be sorry.

Why? I charge at 40A since getting the car over 3 years ago on the UMC. No problem with the it.

 

[jerry33]

Yep, 72A upgradeable charger confirmed in the refreshed models, but I should have added that I'm pretty sure I'll not upgrade.

I suspect this will change after you take a couple of road trips.

 

[kort677]

the difference in speed of charging is what you should be concerned about.
how fast the car charges from 0 miles to full is not a huge concern for me and many others, a few hours at most is the difference between the faster and slower charge rates.
if you don't care about the costs and you think you need a faster turn around then do it.

 

[kort677]

Don't use a UMC at 40 amps, or you'll be sorry.

please elaborate.
like another contributor I have charged my cars at 40 amps for a few years, what damages am I open to?

 

[HankLloydRight]

Why? I charge at 40A since getting the car over 3 years ago on the UMC. No problem with the it.

please elaborate.
like another contributor I have charged my cars at 40 amps for a few years, what damages am I open to?

Same here, never had a problem with my original UMC at 40amps over 2+ years.

 

[ChrisJ]

I suspect this will change after you take a couple of road trips.

There's a new super charger going in 3 miles from my home, so any quick charges for long road trips would start there.

 

[Edmond]

please elaborate.
like another contributor I have charged my cars at 40 amps for a few years, what damages am I open to?

Many people over the years report here that they've had one UMC after another fail. (One had his replaced 5 times) It was only when they dropped to 30A charge the UMCs began to last. Ya, I don't like it either.

I realize your experience is different so far, but that doesn't matter when you have to buy a new UMC. Is your UMC warm or cool when charging at 40?

 

[HankLloydRight]

There's a new super charger going in 3 miles from my home, so any quick charges for long road trips would start there.

I live 3 miles from one supercharger, and 8 miles from another in the opposite direction. If you have a 40am UMC in your garage, I can assure you, you'll *never* use the local supercharger, even for long road trips.

You simply charge your battery to 90%, 95% or 100% (depending on other factors) during the night before you leave and when you're ready to go, just go. And say your battery is already at 90% and you want to Supercharge to 100% before a "long trip", that's not a "quick charge", that's at least 30 minutes if not longer.

Even at a lowly 40amps, you can fully charge a MS battery overnight.

 

[Only Trons]

I am on my fourth UMC. I always charge at 40 amps. Most of the time I only need 1 - 1.5 hours to recharge back to 90%. A few times I've rolled back into my garage with around 30 miles remaining, so the car charged at 40 amps for somewhere between 6 and 7 hours. I don't believe (but can't prove/disprove) that problems with my previous UMCs were as a result of charging at 40 amps. No external damage (melting, disfiguration, etc) were seen on the 3 failed units. For each of the failed units, the service center told me that the contactors within the plug head were "bad". I've had my fourth UMC for about a year now with no problems.

And in response to the question noted by @Edmond: my UMC is warm when charging for several hours -- but just warm....never hot.

 

[David99]

Early UMCs had some issues but Tesla swapped them out. I never had trouble, but they gave me a newer one anyways. I always charged at 40 Amp and it gets really hot here in the summer. Never had issues with the UMC.

 

[kort677]

I realize your experience is different so far, but that doesn't matter when you have to buy a new UMC. Is your UMC warm or cool when charging at 40?

quite frankly I've never fondled it. this is my second model s and my second unit, both units have been problem free.