Ideal range gradually dropping off

[shark2k]

While 36 hung on for a long time, the fact that it switched would suggest nothing is wrong with it.

Just want to clear this up for myself. Each number represents the lowest brick, so you read from left to right, then go to the next line, correct? Also, when does it capture the lowest brick? I know you said Daily Lowest, so does it capture it at the same time every day, even if the car is being driven? Just curious.

Thanks for the responses.

-Shark2k

 

[Doug_G]

Just want to clear this up for myself. Each number represents the lowest brick, so you read from left to right, then go to the next line, correct? Also, when does it capture the lowest brick? I know you said Daily Lowest, so does it capture it at the same time every day, even if the car is being driven? Just curious.-Shark2k

Yes, you just read it the same way as this paragraph, left to right. I'm not sure when the data is collected; I'd have to look at the individual timestamps, but I don't think it's important. It's a once-a-day number.

 

[shark2k]

Cool. Thanks for the info Doug.

-Shark2k

 

[Botbldr45]

"Old #992" with over 12000 miles on it charges up to 182 in standard mode........ pretty reliably.

 

[dhrivnak]

My 1.5 with 7000 miles (I'm the 2nd owner) is getting about 179 ideal miles after charging in standard mode. I charged the last two times with the 120V mobilUMC and was pleasantly surprised to see the ideal miles jump up to 183 miles. Is the slow charging really better for the battery or is the difference likely due to a quirk in the charging algorithm? Here is a plot I have kept over the last 6 months with both standard miles and ideal miles.

 

[Doug_G]

If you charge at lower power it squeezes in a few more electrons. Not sure why.

 

[fraccy]

If you charge at lower power it squeezes in a few more electrons. Not sure why.

Have been talking about charging with Tesla in the UK. He has said quite the opposite to this - that if you repeatedly charge at low power (ie 13a*240v here) it may drop off a bit. He recommended driving it below 30%, leaving it for 20 minutes, and doing a full range charge on 32A or above once in a while (which I never do).

He said the biggest factor was ambient temperature during the charge - the lower the temperature the lower the full charge reading. I've seen some anecdotal evidence for this. I usually get 188/189 on standard in my garage which is built into the house and therefore never particularly cold, but outside overnight at a different location when I guess the temperature was about 5C, I got about 184. On other occasions it is often 186/187. As soon as I get home I then get 188 again. Whether that's due to a subtle difference in supply I don't know and its only a handful of occasions, but its certainly warmer when its charging inside at the moment.

 

[richkae]

A few hours after the charge ends can make a significant difference.
If I time my standard mode charge to finish immediately before I need the car, it frequently end at 189
If the charge finishes several hours before I need the car, I quite often find it at 186 or 187.
( Charging at 240 volts 40 amps )

If in those few hours after the charge ends the car is getting a more accurate picture of the state of charge - perhaps a slower charge rate allows it to have a more accurate SOC all the way to the end, and not stop charging until it is slightly more full.

 

[Dragon]

I charge at home with 220V and 16A. Two times I charged at 63A and found out, that the following charge with 16A will get me more ideal range. The first time it was summer and my car did 302 km on standard, then following the 63A charge the next 16A charge was 308 km. This weekend it was up to 302 km (again reached by charging with 16A after a 63A charge) after it was everytime below 300 since October.
Enviromental temperatures seem to affect the maximal range, my lowest range was 293 km after a very cold night.

 

[JRP3]

Lower charge current should mean a higher SOC since the cell voltage more accurately reflects the resting SOC. When charging at higher currents the cell voltage is pushed artificially higher from internal cell resistance, so for example if charging at 20 amps the cell would show 4.0V at a lower SOC than at that same voltage when charging at 10 amps. It's like filling a bucket with high pressure hose as opposed to a slow stream, the high pressure causes some water to spill out. The bucket fills faster but doesn't get quite as full. Even though the charger tapers the charge near the end there is still residual high voltage from the higher current charging.

 

[tetsuos]

Wow... I'm not even close to these numbers. When I first got my Roadster in March, I was at 298 km ideal in standard mode. I'm now usually around 278-283 km ideal. Odometer is around 10000 km. I am in HK, which has a much higher ambient temp than most other Tesla climates, which I suspect may have something to do with the drop off...

 

[Alan]

Lower charge current should mean a higher SOC since the cell voltage more accurately reflects the resting SOC. When charging at higher currents the cell voltage is pushed artificially higher from internal cell resistance, so for example if charging at 20 amps the cell would show 4.0V at a lower SOC than at that same voltage when charging at 10 amps. It's like filling a bucket with high pressure hose as opposed to a slow stream, the high pressure causes some water to spill out. The bucket fills faster but doesn't get quite as full. Even though the charger tapers the charge near the end there is still residual high voltage from the higher current charging.

Thanks for that explanation. I must try a "top off" after leaving the car for say 12hours to see if that reports a little higher ideal miles.

 

[tomsax]

Wow... I'm not even close to these numbers. When I first got my Roadster in March, I was at 298 km ideal in standard mode. I'm now usually around 278-283 km ideal. Odometer is around 10000 km. I am in HK, which has a much higher ambient temp than most other Tesla climates, which I suspect may have something to do with the drop off...

It would be great to get your data for the Roadster Owner Based Study of Battery Pack Capacity Over Time

 

[cinergi]

Those of you noticing more than a drop of 7+ IM in less than 10-15k miles -- how often do you drive in performance mode? Especially paired with warmer outdoor temperatures?
(It seems that when I drive long enough in performance mode, I cause a drop in my IM, especially if it's hot out)

 

[NigelM]

No drop off whatsoever after 6 months and 4k miles in hot ambient climate, but I never drive in performance mode. Maybe someone wants to make a comparison?

BTW, took a 50 miles journey the other day topless....wow, the range went down fast!

 

[tomsax]

Those of you noticing more than a drop of 7+ IM in less than 10-15k miles -- how often do you drive in performance mode? Especially paired with warmer outdoor temperatures?
(It seems that when I drive long enough in performance mode, I cause a drop in my IM, especially if it's hot out)

The best way for people to help answer these questions is to submit the relevant data extracted from their log files to RichKae's study:

Roadster Owner Based Study of Battery Pack Capacity Over Time.

Please capture your log files and submit the extracted summaries to Rich. This will allow for a more quantitative study than we can get from posts to a thread.

 

[dsm363]

I just had my annual service (first one) and my ranger said that for the car to recalculate the ideal miles, it needs to go from a full (can be a standard charge) down to about 30 miles left on a single run (can't turn the car off the entire trip).

 

[tomsax]

I just had my annual service (first one) and my ranger said that for the car to recalculate the ideal miles, it needs to go from a full (can be a standard charge) down to about 30 miles left on a single run (can't turn the car off the entire trip).

The Tesla service guy I trust the most called that story an "urban legend." I do believe letting the battery get down below 30% in standard mode then doing a full range mode charge does help the car calibrate the battery pack. Letting it sit after the range mode charge also helps level the modules which can improve the pack's performance.

 

[Doug_G]

I just had my annual service (first one) and my ranger said that for the car to recalculate the ideal miles, it needs to go from a full (can be a standard charge) down to about 30 miles left on a single run (can't turn the car off the entire trip).

I'm with Tom on this one. It's pretty obvious that there are a bunch of of "Ranger Legends" out there.

The available energy is determined by the difference between the strongest and weakest strings. During charging the strongest string hits the maximum permissible voltage first, so it limits how high you can charge. While driving the weakest string hits the lowest permissible voltage first, so it limits how low you can drain the pack. Leveling improves the pack capacity by reducing the difference between the strongest and weakest strings.

I'm pretty sure that Tesla can estimate the pack capacity just by looking at the strongest and weakest strings. Now if the pack is badly out of balance then leveling it by using a Range mode charge, then letting it sit for an hour to balance, will help. But it won't fundamentally "improve" the pack capacity; it will just try to make sure the pack is as close to its potential as possible.

 

[dsm363]

The Tesla service guy I trust the most called that story an "urban legend." I do believe letting the battery get down below 30% in standard mode then doing a full range mode charge does help the car calibrate the battery pack. Letting it sit after the range mode charge also helps level the modules which can improve the pack's performance.

Ok. After reading your post earlier, I charge in range mode, drove until I had about 30 miles left, then recharged in range mode so hopefully that helps.