# Power limitation observations on SR+



## VanIsleGuy (Feb 19, 2019)

I've owned my SR+ for a little over a week now, this being my first EV. I have had some observations about regen and power limits which I found interesting. I've been a bit surprised at how warm ambient temperature can be and I still get restricted regen but full acceleration power. I've found even up in the +15C (60f) range I'm getting limited regen, and it never goes to full on my drive home (~10min) from work. It isn't until it gets closer to 20C (68f) outside that the restriction goes away. This morning it was chilly, 8C (46f) when I got in the car (I didn't have it plugged in last night) and I was both power and regen limited, and had the snowflake icon. I'm purposely taking my car down to low charge so I can try the supercharger and see what charging rate I can get, so I'm probably at about 20% SOC. After driving for a few minutes, I was surprised to see my regen went to full power, but I was still limited on acceleration power. I'm wondering if this is due to the SOC, or the cold (snowflake icon never went away). 
Also curious if this is normal for all M3's, or if it is more of a factor on the SR pack. 

To be clear, I am in LOVE with this car. This post is not to complain, I can't stop talking about it to anyone who will listen. I'm just curious and learning about the limitations and behavior.


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## Frully (Aug 30, 2018)

Yeah, below 15C you lose some regen, down to about 0C no regen.
Power draw doesn't seem to be a problem until well below 0C.

It doesn't seem obvious at first but regen actually puts a lot of power toward the battery...well above level 2 rates, up into low supercharge rates.
Cold soaking a battery near 0C seems to limit power a bit if not actively charging...but it really doesn't like to take the 50kw that regen could throw at it.


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## JWardell (May 9, 2016)

VanIsleGuy said:


> I've owned my SR+ for a little over a week now, this being my first EV. I have had some observations about regen and power limits which I found interesting. I've been a bit surprised at how warm ambient temperature can be and I still get restricted regen but full acceleration power. I've found even up in the +15C (60f) range I'm getting limited regen, and it never goes to full on my drive home (~10min) from work. It isn't until it gets closer to 20C (68f) outside that the restriction goes away. This morning it was chilly, 8C (46f) when I got in the car (I didn't have it plugged in last night) and I was both power and regen limited, and had the snowflake icon. I'm purposely taking my car down to low charge so I can try the supercharger and see what charging rate I can get, so I'm probably at about 20% SOC. After driving for a few minutes, I was surprised to see my regen went to full power, but I was still limited on acceleration power. I'm wondering if this is due to the SOC, or the cold (snowflake icon never went away).
> Also curious if this is normal for all M3's, or if it is more of a factor on the SR pack.
> 
> To be clear, I am in LOVE with this car. This post is not to complain, I can't stop talking about it to anyone who will listen. I'm just curious and learning about the limitations and behavior.


That's correct, charging/regen starts limiting below room temperature. Discharge/acceleration starts limiting below freezing. This is a normal property of lithium ion batteries.


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## VanIsleGuy (Feb 19, 2019)

So does it limit acceleration based on SOC then? I noticed on my drive at lunch (finding every excuse to go for a drive) that even once the snowflake icon dissapeared and I got regen back, that I was still acceleration limited (now sitting below 20%).


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## TrevP (Oct 20, 2015)

Model 3 does not have a dedicated battery heater so it relies on waste heat recovery from the motors and power electronics. It's more efficient energy-wise but the side effect is that it takes longer for the battery cells to heat up. 15°C isn't cold but it's just enough for the battery to be below minimum temps overnight to restrict regen in the morning. Once the temps reach 20°C+ consistently you should have full regen in the mornings. 10 minutes isn't really that far of a commute to get things warm but you *could* stomp on it a bit, I bet that generates heat fairly quickly for you


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## TrevP (Oct 20, 2015)

VanIsleGuy said:


> So does it limit acceleration based on SOC then? I noticed on my drive at lunch (finding every excuse to go for a drive) that even once the snowflake icon dissapeared and I got regen back, that I was still acceleration limited (now sitting below 20%).


Yes, regen and power are limited to where your SoC is. Too high and they'res nowhere for the regen power generated to go, too low and the car won't deliver lots of power so you'll likely see dotted lines on the top end of the power line. I see the same thing on my X


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## Frully (Aug 30, 2018)

VanIsleGuy said:


> *So does it limit acceleration based on SOC then?* I noticed on my drive at lunch (finding every excuse to go for a drive) that even once the snowflake icon dissapeared and I got regen back, that I was still acceleration limited (now sitting below 20%).


Yes, Down below about 15% (surely depends on model of battery) you start losing accel power. Snowflake on top of low SOC will further limit power.


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