EA DC charge session data points

[urundai]

Does the ramp UP in the end indicates the battery charging could be optimized more? Probably ramped down drastically after 65% than needed?

Overall, very disappointing charge curve.

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[fastwheels]

@fastwheels Thanks for the info.
Small correction, the charging rate is KW, the total energy delivered is kWh.

This whole 60% drop-off is really baffling me! 143KW to 43KW is a big drop off !

As @SeaGeo is theorizing looks like someone have fat fingered a configuration in the BMS to cause this.

thanks - changed to KW.

 

[SeaGeo]

Thanks @fastwheels! Looks like it took a little bit for it to warm up while charging still, but not bad at all.

I wish EA or Rivian showed both voltage and amperage as well. Were your values read from the charger or the car?

Has anyone asked their guide for more info about the behavior that we're seeing where it's dropping off a cliff at ~65%? That's very unusual for an EV, and it'd be great to hear what Rivian says about it. You could also mention you're not seeing a curve that's particularly close to the 140 miles in 20 minutes despite what looks to be like a pretty good charging session.


When you're referring to range added, I'm assuming that's in all purpose mode with the 20s?

 

[SeaGeo]

Does the ramp UP in the end indicates the battery charging could be optimized more? Probably ramped down drastically after 65% than needed?

Overall, very disappointing charge curve.

It'd typically indicate that it was thermally throttling. The only newly released EV I can think of that hit's a brick wall for temps is the egmp cars @Aardvark, but those aren't as... odd as this.

If that's the case, we're going to have some major issues in anything other than winter. If it actually is thermally throttling, and this isn't essentially an error in the programmed curve logic, then anything other than a warm winter day for @fastwheels is going to be really frustrating. Which is another thing to ask guides/rivian about.

@fastwheels are the cooling fans going crazy during this?

 

[SANZC02]

Thanks @fastwheels! Looks like it took a little bit for it to warm up while charging still, but not bad at all.

I wish EA or Rivian showed both voltage and amperage as well. Were your values read from the charger or the car?

Has anyone asked their guide for more info about the behavior that we're seeing where it's dropping off a cliff at ~65%? That's very unusual for an EV, and it'd be great to hear what Rivian says about it. You could also mention you're not seeing a curve that's particularly close to the 140 miles in 20 minutes despite what looks to be like a pretty good charging session.


When you're referring to range added, I'm assuming that's in all purpose mode with the 20s?

I have a question about the ramp up.

Is it normal on other EV’s to ramp up over 15 or more minutes? I only have the experience with my Tesla where I see peak rate within 1 or 2 minutes, it then will start to taper down. He did not hit peak rate until 18 minutes into the session.

 

[fastwheels]

Thanks @fastwheels! Looks like it took a little bit for it to warm up while charging still, but not bad at all.

I wish EA or Rivian showed both voltage and amperage as well. Were your values read from the charger or the car?

Has anyone asked their guide for more info about the behavior that we're seeing where it's dropping off a cliff at ~65%? That's very unusual for an EV, and it'd be great to hear what Rivian says about it. You could also mention you're not seeing a curve that's particularly close to the 140 miles in 20 minutes despite what looks to be like a pretty good charging session.


When you're referring to range added, I'm assuming that's in all purpose mode with the 20s?

I was comparing values from both the truck and the EA screen - they were very close.

Range added based on All Purpose. The truck has the 22" wheels.

 

[SeaGeo]

I have a question about the ramp up.

Is it normal on other EV’s to ramp up over 15 or more minutes? I only have the experience with my Tesla where I see peak rate within 1 or 2 minutes, it then will start to taper down. He did not hit peak rate until 18 minutes into the session.

There are three broad answers to this.

If you start very early, a lot of EV's will limit the amperage a bit. But that's generally in the single digits.

Beyond that, if it's below optimal temps and you have a fairly flat backbone curve, then it isn't unusual. Especially without preconditioning. That's what I expect was going on where he was sitting between 130 and 190kw.

Assuming the battery is warm enough, and it's maxing out the amperage for the charger, it will slowly increase the rate as the voltage increases. I saw EVGO reporting 389v with an empty pack for Kyle the other day, and max should be around 450 to 459v. But that would be a gradual increase from say... 195kw up to about 210 at max. and then it should slowly ramp the amperage down as SOC increases like you see with your tesla.

 

[SANZC02]

I was comparing values from both the truck and the EA screen - they were very close.

Range added based on All Purpose. The truck has the 22" wheels.

Nice you have the 22s.

Any chance you can share some of your watts per mile ratings and some GOM of range in different modes based on charge level?

 

[SeaGeo]

I was comparing values from both the truck and the EA screen - they were very close.

Range added based on All Purpose. The truck has the 22" wheels.

Thanks. I'm surprised they were close. Prior folks reported a pretty big difference, which I was attributing to high current as well as their HVAC system running hard.

 

[rraj2k81]

thanks - changed to KW.

In case you are curious,

KW is power being delivered by the charger into the battery at any given time
KWh is the total energy delivered/expended over a 1-hour period.
Electric Energy (in KW) = {Voltage (V) * Current (I)} / 1000

So, if the charger delivered an average rate of 100KW over 1 hour,
the charger delivered = 100KW * 1h = 100KWh of energy.

If the charger delivered at an average rate of 100KW in 15 minutes,
the total energy delivered is = (100KW X (15/60)h) = 25 KWh

So, if the charger delivered a constant rate of 400A @400V over 15 minutes the total energy delivered would be = 400A x 400V x (15/60) = 160KW x (15/60)h = 40KWh

I am basing these calculations in ideal conditions

If you already know this, feel free to ignore.

Someone please correct my math and definition if I made a mistake.
It has been a while since I did my power physics.

 

[fastwheels]

@fastwheels are the cooling fans going crazy during this?

I could hear them but they were not 'going crazy'. They have been a lot louder after driving it for a while on a 50+ degree day.

 

[SeaGeo]

I could hear them but they were not 'going crazy'. They have been a lot louder after driving it for a while on a 50+ degree day.

That's really interesting. So then either it's not a thermal issue with charging, or the HVAC system isn't reacting to cool it like it should while charging (and thus it's throttling). Given that it seems that this cliff seems to be fairly consistent around 65%, I suspect it's coded in for some reason.

 

[fastwheels]

Nice you have the 22s.

Any chance you can share some of your watts per mile ratings and some GOM of range in different modes based on charge level?

This is what part of what I posted after my first DC charge - to 100%:

For the drive home I selected Conserve Mode. The road was still wet (light rain & 36 degrees, minimal wind) and was in a slightly hilly area with cruise control set for 60. After about 20 minutes I checked the 15 min avg efficiency number and saw it was up to 2.52 mile/kW. The last part of the drive I lowered the cruise to 55 mph and saw the 15 min avg number go up to 2.82. The road for this last section was flat. Way too early to know how accurate that number is, but it does give some idea of how Conserve mode and lower speeds impact range.

Is that what you are looking for? I will be making a 600 mile trip this weekend and will try to keep an eye on mileage.

 

[SeaGeo]

I'm going to combine this curve, and what Sid pulled recently as well on the post I made the other day. Knowing that the below plot was on a charger limited to ~350A, everything below ~55% is going to be lower than what you got @fastwheels. Otherwise, I have a feeling it's fairly consistent.

 

[RoadForce]

I wonder if the system interprets 85% as 100% and uses that to do a typical taper when fully charging?

You know, i was wondering the same thing. Seems like the kW rate drop @ 60-65% SOC is early, at least given some other data i have seen on the internet.

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