L2 Charging Question

[squinn61853]

(I posted this as a response to a reddit thread, but I can't originate a post there because I don't have "karma").

One month into my R1T Tri ownership, with hardwired ChargePoint Homeflex charger on 60A breaker, I have always (about 6 times now), gotten between 11.1 - 11.4 kW charging speed up to about 77 - 78%. Then, it plummets down to around 6.7 (with short spans of 3.2ish), for the remainder of the charging session.

I knew that there'd be a drop for the last 20% on DCFC, but I was surprised to see this on AC charging - but, since it's been so consistent, I just assumed it was the correct behavior. Neither the charger itself, nor the plug at the truck, have ever felt hot...

But in the reddit thread mentioned above, people seem to indicate that they get "full speed" level 2 charging almost right up to 100%.

So, is the consensus that, for AC (L2) charging, there should be NO (or very little) slowdown in charging speeds, even above 80%?

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[av8or]

Full speed all the way. OG quad large pack.

 

[windblowlc]

Full speed all the way. OG quad large pack.

OP is talking about gen 2 Tri. We all know gen 1 has no issue with level 2 charging.

(I posted this as a response to a reddit thread, but I can't originate a post there because I don't have "karma").

One month into my R1T Tri ownership, with hardwired ChargePoint Homeflex charger on 60A breaker, I have always (about 6 times now), gotten between 11.1 - 11.4 kW charging speed up to about 77 - 78%. Then, it plummets down to around 6.7 (with short spans of 3.2ish), for the remainder of the charging session.

I knew that there'd be a drop for the last 20% on DCFC, but I was surprised to see this on AC charging - but, since it's been so consistent, I just assumed it was the correct behavior. Neither the charger itself, nor the plug at the truck, have ever felt hot...

But in the reddit thread mentioned above, people seem to indicate that they get "full speed" level 2 charging almost right up to 100%.

So, is the consensus that, for AC (L2) charging, there should be NO (or very little) slowdown in charging speeds, even above 80%?

This exact L2 charging behavior has been reported by all gen 2 Tri owners, including me. Instead of improving on charging rate, Rivian is going backward with gen 2.

 

[bfilippo]

Same experience with my Gen2 Dual Standard R1T, which means it’s not even just the battery, but something more to do with Gen2 design.

 

[dkopelove]

I have a gen 2 R1S. My level 2 charger is an OpenEVSE. I saw the same thing as you.

I logged the EVSE temp and the pilot signal to see if there was derating.

Curiously, the pilot didn't drop but the reduced power happened when the EVSE temp hit ~60C.

While I can't recommend this, I added a case fan powered by the contactor and cross-drilled for ventilation. Now I get the full 11.5kW for the entire charge session.

My charger is in the garage, 5' above the floor. I'm not worried about water ingress, but that is the primary reason this isn't recommended.

You also need to be sure that your breaker is properly sized for the conductors and insulation of your L2 circuit.

The enclosure is a proxy for the conductor temp, which is honestly not a great design, but the EVSE designers had to measure something.

 

[bigsky]

While it is a Gen 1 Quad in my garage, I never have babysat any charging session. When checking after charging is completed, dividing charge put into my R1S by time taken to do that, result is always north of 10.5 kWh.

 

[MarkNorman]

Traded my Gen 1 QM R1T for a Gen 2 DM R1S Large pack. Generally great, but charging (both DCFC and L2) has been a huge let down compared to my Gen 1. On my home L2, it will normally pull 48A/11kw until around 76% then starts derating to 8 kw, then 4 kw, then <1kw above 90%. But not every time. Sometimes it pulls 48A/11kw all the way up to 99% (in prep for roadtrips). Have a service appointment 1/15, so we’ll see.

 

[portdirect]

While it is a Gen 1 Quad in my garage, I never have babysat any charging session. When checking after charging is completed, dividing charge put into my R1S by time taken to do that, result is always north of 10.5 kWh.

This is my experience as well with our gen1’s so far the gen2 appears to be a major step backward in terms of l2 charging.

 

[sfvR1S]

Slightly OT but are people charging to 100% for daily use? I thought Rivian recommended 70%.

 

[portdirect]

Slightly OT but are people charging to 100% for daily use? I thought Rivian recommended 70%.

I’m not, we charge to 85% each day - but often need to ‘top-off’ in the morning (usually to ~95%) if we are taking longer trips to avoid needing to stop at a dc fast charger - this was/is great with our gen1’s as i could start the charge at 7 am and be on the road with the family at around 8:30 - with our gen2 so far this Top off seems to be taking 5 to 7 hours to achieve the same boost, which means in practice we’ll just use the gen1 whenever we need to go on an adventure…

 

[MarkNorman]

Slightly OT but are people charging to 100% for daily use? I thought Rivian recommended 70%.

I usually charge to 70% for normal use but often want to charge higher to go on longer trips. This used to work well in my Gen 1, but is very frustrating in my Gen 2 <4kw at 85% is horrendous.

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