Beginners' guide to EV charging?

[IlliniRivian]

I understand to maximize battery life you typically want to avoid charging to 100%.

Is there a setting with Rivian that allows you to plug it in to your home charger but stop at a certain point (e.g., 80%) so you don't need to go out in the middle of the night to unplug?

Sponsored

 

[norivian]

So this is where things get a bit confusing. The R1S and R1T can charge at most 11.5 kW on AC charging. That's the max output of the AC-->DC converter that the car has. A 240v outlet at 48 amps is 11.5kW. However, per the building code (and there are some intricacies here that others will probably jump on) your fuse needs to be 25% (20?%) greater than the continuous power usage. So 48*1.25 = 60 amps. ANything more than 60 amps would return no gain for the RIvian, but it would for a couple of other cars that can charge at higher amperage on level 2.

THat being said, realistically the difference between a 40 amp charger (50 amp fuse) and 48 amp charger (60 amp fuse) probably doesn't matter as you'll generally be charging it over night, and over the course of an hour that's only 1.9kW difference in charge. So you'll only pick up ~ 4 extra miles per hour.

The continuous load (i.e., the charging current) can only be 80% of the ckt brkr rating. For a 60A brkr, approx 48A (≈ 50A).

 

[SeaGeo]

The continuous load (i.e., the charging current) can only be 80% of the ckt brkr rating. For a 60A brkr, approx 48A (≈ 50A).

yeah, thanks. Was having a brain fart as to if it was 75% or 80%.

 

[norivian]

I understand to maximize battery life you typically want to avoid charging to 100%.

Is there a setting with Rivian that allows you to plug it in to your home charger but stop at a certain point (e.g., 80%) so you don't need to go out in the middle of the night to unplug?

I imagine you can adjust the setting (in the vehicle or through the app) to only charge to the percentage you want… just like Tesla. (Sorry, I am still waiting for my R1T.)

 

[CommodoreAmiga]

If you don’t want to install a hardwired charger. Plug-in chargers can only be on a 50V branch ckt as far as i know.

Up to 32 amps on a 40amp circuit (240 volt split phase).

Non-hardwired EVSEs can be up to 40A, which would require a 50A circuit. The Rivian "included" portable EVSE maxes out at 32A, but that is not a limitation of code, but rather a choice Rivian made. 40A units are available from many brands.

 

[CommodoreAmiga]

I understand to maximize battery life you typically want to avoid charging to 100%.

Is there a setting with Rivian that allows you to plug it in to your home charger but stop at a certain point (e.g., 80%) so you don't need to go out in the middle of the night to unplug?

I imagine you can adjust the setting (in the vehicle or through the app) to only charge to the percentage you want… just like Tesla. (Sorry, I am still waiting for my R1T.)

By default, the Rivian software encourages you to stick to a 70% limit, which it can enforce automatically. It also lets you pick 85% or 100%.

 

[norivian]

Non-hardwired EVSEs can be up to 40A, which would require a 50A circuit. The Rivian "included" portable EVSE maxes out at 32A, but that is not a limitation of code, but rather a choice Rivian made. 40A units are available from many brands.

Thanks for that info about Rivian charger. I installed a NEMA 14-50 Chargepoint on a 50A brkr at home. It automatically adjusts to 40A whenever i charge (a Tesla). I didn’t get a hardwired charger so i can plug-in other chargers or take my charger if i relocate.

 

[ajdelange]

It also lets you pick 85% or 100%.

Can I set 82% or am I forced into one of the presets?

 

[CommodoreAmiga]

Can I set 82% or am I forced into one of the presets?

afaik, just those presents right now.

 

[ajdelange]

Non-hardwired EVSEs can be up to 40A, which would require a 50A circuit. The Rivian "included" portable EVSE maxes out at 32A, but that is not a limitation of code, but rather a choice Rivian made. 40A units are available from many brands.

There is a reason for this. NEC allows 14-50R to be installed on 40A circuits. The max that can be taken from a 40A circuit is 32A.

 

[CommodoreAmiga]

There is a reason for this. NEC allows 14-50R to be installed on 40A circuits. The max that can be taken from a 40A circuit is 32A.

That may be Rivian’s logic, but other EVSEs exist that plug in via NEMA 14-50R and take 40A. It isn’t a code limitation.

 

[ajdelange]

That may be Rivian’s logic, but other EVSEs exist that plug in via NEMA 14-50R and take 40A. It isn’t a code limitation.

Tesla uses the same logic in their current version UMC though earlier versions did allow 40A. Tesla does still (I think) offer a portable charger with a fixed 14-50P (UMC takes adapters) that allows 40A to be drawn. It is thus the responsibility of the user to be sure he isn’t on a 40A circuit. The Rivian/UMC approach protects the user from making that mistake and thus the companies from liability.

 

[svet-am]

That may be Rivian’s logic, but other EVSEs exist that plug in via NEMA 14-50R and take 40A. It isn’t a code limitation.

It's not really a matter of _what_ the capacity is, the NEC is pretty standard. For the sake of NEC, EVSE is considered a continuous load. For a continuous load the EVSE can (at maximum) draw 80% of the rating for the line. So, on a 60A circuit it's 42A, 50A circuit it's 40A, on a 40A circuit it's 32A.

The NEC is a professional document and requires payment to access the full real document but NREL has a good write up here (slide 25): https://www.nrel.gov/docs/fy21osti/78085.pdf

I'm not saying companies don't make equipment that violate _current_ NEC because section 625 on NEC has changed a lot over the past 20 years as electrification has happened and EVSEs have gotten more complex.

 

[CommodoreAmiga]

Tesla uses the same logic in their current version UMC though earlier versions did allow 40A. Tesla does still (I think) offer a portable charger with a fixed 14-50P (UMC takes adapters) that allows 40A to be drawn. It is thus the responsibility of the user to be sure he isn’t on a 40A circuit. The Rivian/UMC approach protects the user from making that mistake and thus the companies from liability.

Never said otherwise. I'm really not sure what your point is.

It's not really a matter of _what_ the capacity is, the NEC is pretty standard. For the sake of NEC, EVSE is considered a continuous load. For a continuous load the EVSE can (at maximum) draw 80% of the rating for the line. So, on a 60A circuit it's 42A, 50A circuit it's 40A, on a 40A circuit it's 32A.

The NEC is a professional document and requires payment to access the full real document but NREL has a good write up here (slide 25): https://www.nrel.gov/docs/fy21osti/78085.pdf

I'm not saying companies don't make equipment that violate _current_ NEC because section 625 on NEC has changed a lot over the past 20 years as electrification has happened and EVSEs have gotten more complex.

Also not sure what your point is. I don't see where anything I've said contradicts what you said.

 

[svet-am]

Never said otherwise. I'm really not sure what your point is.


Also not sure what your point is. I don't see where anything I've said contradicts what you said.

You said it’s not a code requirement and it is.

Sponsored