150 kw vs 115 kw Curves Different After Initial Burst?

[DarkStang]

I understand that SR Select models have a slower peak charge of 115 kw. However, I’ve heard that the 150 kw models only peak at that rate for the first few minutes of the curve before sloping down to 115 kw or below anyway.
My question is, does this have a larger effect on the curve as a whole? Or do the curves behave similarly after that first hump? I have a SR on order and don’t think the charging difference is worth it to me if it’s only for a few minutes of peak charge, but wasn’t t sure if the entire curve is noticeably slower overall.

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[timbop]

The difference in ER vs SR DC fast charging power has to do with the number of cells and the way they are wired, not any kind of software setting. The ER has 4 modules in parallel and the SR has 3, so the ER can draw 30% more power at a given state of charge compared to the SR. So, the shape of the curves should be very similar but the exact values for power level will be different (ie 30% lower on the SR).

AC L2 power draw will be virtually identical, except that the ER will take 30% longer to charge to some nominal state of charge (like 90%)

 

[DarkStang]

Thanks! Yeah, I've been trying to estimate the average kw speed for a 10-80% charge compared to an ER. Obviously the ER will get a good deal of additional charge at the start of the curve, but was hoping the SR didn't have a huge disadvantage in the 115 kw and under range after that first big burst.

I have found some ER test curves on some sites, but nothing for the SR. I have averaged those rates for each 10% block of the curve and figured the ER averages probably around 80 kw over the whole session. Hoping the SR won't be too far below that, maybe 70 kw or so, which I can live with.

 

[PaulP]

My latest fast charges on 100kw chargers. It is on a Select AWD SR.

 

[timbop]

Thanks! Yeah, I've been trying to estimate the average kw speed for a 10-80% charge compared to an ER. Obviously the ER will get a good deal of additional charge at the start of the curve, but was hoping the SR didn't have a huge disadvantage in the 115 kw and under range after that first big burst.

I have found some ER test curves on some sites, but nothing for the SR. I have averaged those rates for each 10% block of the curve and figured the ER averages probably around 80 kw over the whole session. Hoping the SR won't be too far below that, maybe 70 kw or so, which I can live with.

When computing the time from 10% to 80% both should be the same: the ER has 30% faster charging but a 30% larger battery. The difference is that the smaller battery means you'll have to charge more often or to a higher percentage to go the same distance.

I suggest playing around with abetterrouteplanner.com to figure it out.

 

[DarkStang]

Awesome, thank you both. Yeah, I've been playing with ABRP, but trying to see what avg. kw charging speed they are assuming when they are giving me charging stop times. Using a separate EV charge time calculator app and plugging in ABRP's % to % estimates, I think they are assuming close to 70 kw average over the session.

Really, what it spits out isn't too bad. In most cases, the ER isn't really giving me that different of an experience than the SR, unless there is a big gap between chargers. Seems like maybe a few extra minutes per stop and maybe one extra stop, but usually they still have to hit the same stops based upon how they are distanced. For the occasional road tips I take 1-2 times a year, I think an extra 20 min of trip time outweighs the $$$ of the bigger battery (of course I couldn't even order an ER if I wanted one at this time).

 

[timbop]

Here's an example from my house in NJ to DC and back with a reference efficiency of 3.3 mi/kwh (works out about right for my car). On the return trip I configured the same 75% max charge level so there are comparable 36 minute 17%-75% stops. You're right that most of the time you can work in a bio break so that the stops are at least productive:

SR:

ER:

 

[ckt]

Attached is one of my recent 30 min charge curve from low state of charge (I think it was 15% SOC for MY 21 Select, don't recall what it ended at)

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