BMS Power Draw

[Coltonw011]

Question for those who have made it through the “break-in” period on their cars. I just charged at EA last night, drove 5.5 miles back to my house and parked the car overnight. Since this is only my 2nd time charging at EA and the first time I lost 20 miles of range overnight, I wanted to check again. Well 4 hours after charging, I had lost 18, and this morning the total was once again 20 miles. I just updated customer care as I’m now 2/2 for 20 mile range loss overnight after charging, and they said right now that’s considered normal until I reach the 2100-2500 break-in period. I took a photo of my avg mi/kWh; I reset the trip meter this morning backing out of the garage before heading to work to compare it with the “since last charge” reading. Now, I drove 5.5 miles home after charging, so about 1.5 kW worth of energy used, but there is about 5.5 kW discrepancy once you remove what I drove home. That’s a lotttt of power running those fans after charging. On the plus side - here’s proof epa numbers are achievable. ~ 40 mile trip where the first part is mix of city and highway speeds (max of 75-80) and I took a different route home where max speed is about 60 with a lot of elevation changes. For those who have passed the break-in period, are you still seeing this kind of fan draw after an EA session?

 

[hydbob]

You should repeat this test not using the EA chargers. After fast charging those fans run a longggggg time.

 

[Coltonw011]

I will gladly do that and report what I find!

 

[MikeTz]

Have you tried switching to %SOC rather than miles. SOC is a better indicator of discharge than an estimated range

 

[Coltonw011]

Have you tried switching to %SOC rather than miles. SOC is a better indicator of discharge than an estimated range

Yes, I was down to 85% after returning home with 89%. Still shakes out to about 20 miles.

 

[Bbq9]

You should repeat this test not using the EA chargers. After fast charging those fans run a longggggg time.

Definitely worth trying. I tend to use EA (free is free)
if I take my sweet time home, (eg give the battery time to get back to normal) I have been seeing a loss of 3-5 miles max overnight.

there were a few times - when charging at home (Level 1) in HOT garage - that the BMS would consume almost all the L1 power. Those were days to not bother charging

 

[Coltonw011]

Definitely worth trying. I tend to use EA (free is free)
if I take my sweet time home, (eg give the battery time to get back to normal) I have been seeing a loss of 3-5 miles max overnight.

there were a few times - when charging at home (Level 1) in HOT garage - that the BMS would consume almost all the L1 power. Those were days to not bother charging

Are you past the break-in? I’m curious if the system becomes less cautious over time like customer care has lead me to believe.

 

[GEWC]

I'm at 2800 miles and I still see similar loss if I charge and go straight home, though I don't charge at EA often and am not sure what my.mileage was last time.

I have a new strategy - I charge right before I go - even at home. This way I minimize loss. So far seems to be much better. Since it charges so quickly even on a home charger, I plug it in when I get up in the am. Plus, bonus, the car seems much more efficient when I do this. I got 6.4 almost all the way to school the other day (16 miles of relatively flat and small up and downs) and it only dropped when I had to go up a big hill at the end.

Next time I drain it enough I plan to try the same strategy at EA - charging right before I need to go somewhere. This is easy for me as there are EA chargers only 2 miles away and they are never full. I'll post here how it goes.

 

[scubastevo80]

Do you keep checking via the app? Tesla owners have similar issues when constantly waking the car up. Are you sure the car is fully “going to sleep” or is something running to make the battery drain (A/C, BMS to cool the batteries/motors, etc)?

 

[Bbq9]

Are you past the break-in? I’m curious if the system becomes less cautious over time like customer care has lead me to believe.

3200 miles … so I guess so

However unlike a number of our peer owners I haven’t really seen any change after the “break in” period. Neither in range or overnight loss

 

[Coltonw011]

Do you keep checking via the app? Tesla owners have similar issues when constantly waking the car up. Are you sure the car is fully “going to sleep” or is something running to make the battery drain (A/C, BMS to cool the batteries/motors, etc)?

The car is put to sleep via a hard press of the door handle every time I park. Key is kept in a faraday box. It’s only after DCFC that I see this kind of loss, which is attributed to the fans running after a charging session. I never check the app as it’s almost useless most of the time (I’m familiar as I own a MS as well).

 

[Coltonw011]

I'm at 2800 miles and I still see similar loss if I charge and go straight home, though I don't charge at EA often and am not sure what my.mileage was last time.

I have a new strategy - I charge right before I go - even at home. This way I minimize loss. So far seems to be much better. Since it charges so quickly even on a home charger, I plug it in when I get up in the am. Plus, bonus, the car seems much more efficient when I do this. I got 6.4 almost all the way to school the other day (16 miles of relatively flat and small up and downs) and it only dropped when I had to go up a big hill at the end.

Next time I drain it enough I plan to try the same strategy at EA - charging right before I need to go somewhere. This is easy for me as there are EA chargers only 2 miles away and they are never full. I'll post here how it goes.

Let me know! Just a new experience losing that much range after a DCFC session - never happened with my MS. I may experiment with how far I have to drive after a session to cool the batteries back down to avoid the fans running. My EA station is only 5.5 miles away from me so not a big deal either.

 

[Bill55]

I have never parked the car right after level 3 charge. I have 5000 miles now and the car loses ~1% a day when I have had it parked for a few weeks in 60-85 degree weather. Charging with 120v temporarily in Dallas. The temperature is about 85 in the garage and the parasitic draw of fans while charging is ~0.6kW so my net charging is 0.4kW. About 3 hours to go up 1% on state of charge.

 

[Coltonw011]

I have never parked the car right after level 3 charge. I have 5000 miles now and the car loses ~1% a day when I have had it parked for a few weeks in 60-85 degree weather. Charging with 120v temporarily in Dallas. The temperature is about 85 in the garage and the parasitic draw of fans while charging is ~0.6kW so my net charging is 0.4kW. About 3 hours to go up 1% on state of charge.

Yea I don’t lose really any range to speak of overnight outside of when I DCFC. It is great about that. And oddly enough, just drove 17 miles to the gym. Worked out for an hour and a half, and the car gained back 14 miles of range - making a 17 mile trip a 3 mile one haha

 

[scubastevo80]

The car is put to sleep via a hard press of the door handle every time I park. Key is kept in a faraday box. It’s only after DCFC that I see this kind of loss, which is attributed to the fans running after a charging session. I never check the app as it’s almost useless most of the time (I’m familiar as I own a MS as well).

Got it. Hopefully it’s a BMS enhancement they can make via a software update.

 

[GEWC]

So I charged at a 150kwh EA station today - from 43% up to 78% - then went and picked up my daughter from school. Had the AC on (72/level 6 - 82 degrees out) and idled for about 10 minutes in the pickup lane. Round trip was 29 miles and I got home with 71% battery. I drove back roads (45mph) to school and took the highway (75mph) home. Round trip is a little over 28 miles and I got home with 71% battery. Car was showing I got 3.7 mi/kwh. Two hours later I took my son to a friend's house and noticed the battery had dropped to 67% and since last charge was now showing 2.7 mi/kwh. I'm currently at just over 3000 miles.

 

[hydbob]

So I charged at a 150kwh EA station today - from 43% up to 78% - then went and picked up my daughter from school. Had the AC on (72/level 6 - 82 degrees out) and idled for about 10 minutes in the pickup lane. Round trip was 29 miles and I got home with 71% battery. I drove back roads (45mph) to school and took the highway (75mph) home. Round trip is a little over 28 miles and I got home with 71% battery. Car was showing I got 3.7 mi/kwh. Two hours later I took my son to a friend's house and noticed the battery had dropped to 67% and since last charge was now showing 2.7 mi/kwh. I'm currently at just over 3000 miles.

The complete disappointment I have now in the range queen being under 3.0 mi/kwh hits me right in the gut...I don't know what to do anymore.

 

[Adnillien]

So I charged at a 150kwh EA station today - from 43% up to 78% - then went and picked up my daughter from school. Had the AC on (72/level 6 - 82 degrees out) and idled for about 10 minutes in the pickup lane. Round trip was 29 miles and I got home with 71% battery. I drove back roads (45mph) to school and took the highway (75mph) home. Round trip is a little over 28 miles and I got home with 71% battery. Car was showing I got 3.7 mi/kwh. Two hours later I took my son to a friend's house and noticed the battery had dropped to 67% and since last charge was now showing 2.7 mi/kwh. I'm currently at just over 3000 miles.

And tomorrow morning it may climb back up even without charging. Don't trust these numbers.

 

[Coltonw011]

So I charged at a 150kwh EA station today - from 43% up to 78% - then went and picked up my daughter from school. Had the AC on (72/level 6 - 82 degrees out) and idled for about 10 minutes in the pickup lane. Round trip was 29 miles and I got home with 71% battery. I drove back roads (45mph) to school and took the highway (75mph) home. Round trip is a little over 28 miles and I got home with 71% battery. Car was showing I got 3.7 mi/kwh. Two hours later I took my son to a friend's house and noticed the battery had dropped to 67% and since last charge was now showing 2.7 mi/kwh. I'm currently at just over 3000 miles.

I would say that there is an over abundance of caution in the bms system at the moment. You’re seeing the same results as me, you drove 30 miles and that wasn’t sufficient enough to cool them properly. Not a big deal, but sort of ruins the “break-in” period I’ve been told to wait for. Hopefully they get it under control.

 

[Coltonw011]

And tomorrow morning it may climb back up even without charging. Don't trust these numbers.

These numbers have been pretty darn accurate. Sure, it may climb a bit, but right now the fans are running far too aggressively it would seem. Again, not a huge deal, but it’s been pretty consistent after DCFC. Car loses substantial range after due to the fans. In turn, it drives down peoples avg mi/kWh. Again, this is only after a DCFC and parking. If you are on a trip you may not notice since you just keep driving.