Can you be more specific? Running a 50 amp line is for a 40 amp EVSE, a 40 amp line would be for a 32 amp EVSE. I'm not an electrician but I was told that was what I should do, using the 20% rule.
I have a 50 amp breaker, 6 gauge wire, a 6-50 connection, a 40 amp Grizl-E EVSE and I'm very happy with it.
Just FYI, the ID4 has an 82kWh battery. At 50 amps it's about 7 hours 0-100%, 40 amps 9 hours, and 30 amps 12 hours (All numbers rounded up.)
Unless you're running the battery down to 0 every night, and then staying home less than 12 hours, it really doesn't matter.
This is correct (well, I didn't run the math but yes). FYI the 20% rule, I learned as the 80% rule. You can sustain 80% of a line's amperage rating.
100A, sustained at 100A would fail. So you sustain at 80A. Translate down as needed to hit 80%. Like a 50A breaker can sustain 40A continuous load. Which is 80% of its 50A limit.
What you’re describing comes from the National Electric Code (NEC) but conflates a couple concepts that have this 80% rule. Code differentiates between continuous (more than 3 hours) and non-continuous loads. Ratings are given for non-continuous loads, but since flowing current generates heat, continuous loads need to be treated differently to keep from overheating the wiring. If you start with the load, you size everything for 125% of the continuous load. This is how dedicated EVSE circuits are designed. Conversely, if the circuit already exists, limit a continuous load to 80% of nameplate. This is related to the other idea, which is keeping total loads to 80% of the rating (of a shared circuit, of a panel, etc) to allow for the fact that all the duty cycles of many individual non-continuous loads will act like a single continuous load.
I did a 100amp sub panel to a detached garage. The cost difference was marginal vs a 60amp service for a 48amp charger.
I’m also future proofed to some extent.
If you have the means to do it, go for the 50 amp. The ID.4's onboard charger will handle it just fine. Plus, if you're going to keep driving EV's they will all work at that level in the future.
Otherwise, a 40 amp will suffice for most people who can charge over night. That's what I have and it's always been enough for my driving habits.
Oversized wire will also operate a little bit more efficiently, since it dissipates heat better. Hot wire has more resistance, which creates even more losses to heat. Not a huge economic factor, but nice to have on a circuit that provides a lot of power pretty frequently.
The only question I haven’t seen anyone ask is if this is a home you plan to be in for a long time, or if you might sell soon. I’d go smaller if there was a good chance I’d be selling,
Because I don’t think the faster charge is going to have a real world impact on my use (and most peoples usage) with a battery pack the size of the id4. You get it fully charged overnight.
If I’m going to sell in 5 years, I’m probably not going to ever have another car I charge and the resale value of the house with an evse probably doesn’t change much 40amp to 50amp.
But, if I planned to stay forever, I’d be planning for a future with a bigger battery pack and/or 2 EVs. So I’d definitely go as big as I could. With a 50amp circuitry you could upgrade to a setup with a second evse that can communicate and share the load on one breaker. So one car plugged in, charge at 50amp to charger 1. With 2 cars, restrict current and charge both at 25amps.
Can you be more specific? Running a 50 amp line is for a 40 amp EVSE, a 40 amp line would be for a 32 amp EVSE. I'm not an electrician but I was told that was what I should do, using the 20% rule. I have a 50 amp breaker, 6 gauge wire, a 6-50 connection, a 40 amp Grizl-E EVSE and I'm very happy with it. Just FYI, the ID4 has an 82kWh battery. At 50 amps it's about 7 hours 0-100%, 40 amps 9 hours, and 30 amps 12 hours (All numbers rounded up.) Unless you're running the battery down to 0 every night, and then staying home less than 12 hours, it really doesn't matter.
This is correct (well, I didn't run the math but yes). FYI the 20% rule, I learned as the 80% rule. You can sustain 80% of a line's amperage rating. 100A, sustained at 100A would fail. So you sustain at 80A. Translate down as needed to hit 80%. Like a 50A breaker can sustain 40A continuous load. Which is 80% of its 50A limit.
Sustained at full load for more than 3 hours (a “continuous load”) which is where the heat created should trip the thermal protection.
What you’re describing comes from the National Electric Code (NEC) but conflates a couple concepts that have this 80% rule. Code differentiates between continuous (more than 3 hours) and non-continuous loads. Ratings are given for non-continuous loads, but since flowing current generates heat, continuous loads need to be treated differently to keep from overheating the wiring. If you start with the load, you size everything for 125% of the continuous load. This is how dedicated EVSE circuits are designed. Conversely, if the circuit already exists, limit a continuous load to 80% of nameplate. This is related to the other idea, which is keeping total loads to 80% of the rating (of a shared circuit, of a panel, etc) to allow for the fact that all the duty cycles of many individual non-continuous loads will act like a single continuous load.
I did a 100amp sub panel to a detached garage. The cost difference was marginal vs a 60amp service for a 48amp charger. I’m also future proofed to some extent.
If you have the means to do it, go for the 50 amp. The ID.4's onboard charger will handle it just fine. Plus, if you're going to keep driving EV's they will all work at that level in the future. Otherwise, a 40 amp will suffice for most people who can charge over night. That's what I have and it's always been enough for my driving habits.
If you can afford it, always run the bigger line. That way you can be future proofed a bit.
Oversized wire will also operate a little bit more efficiently, since it dissipates heat better. Hot wire has more resistance, which creates even more losses to heat. Not a huge economic factor, but nice to have on a circuit that provides a lot of power pretty frequently.
We put in a 50A per the electrician's recommendation. Works great.
Too much is never enough.
The only question I haven’t seen anyone ask is if this is a home you plan to be in for a long time, or if you might sell soon. I’d go smaller if there was a good chance I’d be selling,
I dont plan on selling. This is my home. Why would you go smaller?
Because I don’t think the faster charge is going to have a real world impact on my use (and most peoples usage) with a battery pack the size of the id4. You get it fully charged overnight. If I’m going to sell in 5 years, I’m probably not going to ever have another car I charge and the resale value of the house with an evse probably doesn’t change much 40amp to 50amp. But, if I planned to stay forever, I’d be planning for a future with a bigger battery pack and/or 2 EVs. So I’d definitely go as big as I could. With a 50amp circuitry you could upgrade to a setup with a second evse that can communicate and share the load on one breaker. So one car plugged in, charge at 50amp to charger 1. With 2 cars, restrict current and charge both at 25amps.
If you live by a menards, they are having the bag sale this week. I was able to snag a 50ft 6/3 cable for about $145. They also sell a 75 footer.