Ideal range gradually dropping off

[benji4]

It's almost 7 months to the day my Roadster was delivered, and for the first 4 or 5 months ideal range after a standard charge was consistent in the 192-194 mile range. However, over the past 2 months or so, it's been dropping off a bit pretty much every time I charge, down to 179 miles now after a standard charge last night. Over time of course battery capicity will decline, but it seems a bit rapid. Has anyone else seen such a drop? Should I take the car in to have it looked at?

 

[Dragon]

I heard this is normal. It stays consistent at the beginning, then drops really fast until reaching a plateau and the range will stay there consistent again for some time.
The range on my car is a bit strange. I started with 302 ideal km and now after almost 3 months and 6000 km I'm up to 307-309 km. But had 296 km showing as well, guess the sheets were (are?) a bit unbalanced.

 

[AndrewBissell]

I think they back off the Standard range fast. IMO this is to protect the battery by expanding the top buffer. Only the Range Mode range gives a truer battery capacity reading.

 

[benji4]

I think they back off the Standard range fast. IMO this is to protect the battery by expanding the top buffer. Only the Range Mode range gives a truer battery capacity reading.

That does seem to be consistent with what I saw during my last range mode charge 2 weeks ago. At that point, ideal miles after a standard mode charge was already down to about 182, but when I charged in range mode idea miles ended up at around 240. It would seem like standard mode charging is not getting the battery up to 90% charged anymore (which would be more like 192 miles if range mode is giving 240?). Not really a bad thing I suppose.

 

[hcsharp]

I would bet that if you did a range mode charge, and let it sit for several hours then it would go back to 190 on your next std mode charge. When was the last time you had a software update? The newest software will balance after a std mode charge.

Also, how cold is it getting? Although the gauge has pretty good calibration, it still changes slightly with temperature. We've been getting into the 30s F (0 - 10 C) at night an it will affect both calibration and amount of charge.

 

[benji4]

Firmware was updated about 3 months ago. Also, two weeks ago I did charge in range mode, let it sit for a couple hours before I drove it, and drove about 120 miles before charging in stanadard mode again. No change -- at that point still just 181 miles in standard mode. Today was the first time it dropped below 180 as it completed charging in standard mode at 179 miles. Temperatures have been warm to hot. Around 30 C in the daytime, getting down to maybe 24 C at night. Nothing cooler than that lately though.

 

[Sparrow]

My Roadster #189, which is now over 2 1/2 years old, charges to 177 to 180 miles after a standard charge. My observation is that with cooler temperatures the ideal range is in the lower area around 177 to 178 and in warmer it is around 179 to 180, but I certainly could be imagining it with that observation, since I haven't tracked it on paper . This is checking it a few hours after charging is complete.

 

[Doug_G]

My Roadster #919, which is a little over a year old and about 16,000 km, usually shows 298 km (186 miles) in the morning. When new it showed between 299 and 301 km.

Try doing a Range mode charge, leave it for an hour, and then drive it to get the battery back under 300. That will rebalance the pack.

 

[smorgasbord]

Try doing a Range mode charge, leave it for an hour, and then drive it to get the battery back under 300. That will rebalance the pack.

It's been reported elsewhere on this forum that the latest firmware now balances the pack after standard charges as well. But, seeing what a Range charge gives you would be a good data point.

 

[donauker]

With #227 at 2 1/2 years and 33,300 miles I get standard mode charges in the 162 to 168 mile range and range mode charges have been in the 212 to 218 mile range.

Using Doug_G's log parser (Thanks Doug) you can see the A-hr capacity of the pack

The decline starting around day 550 was due to a firmware update to version 3.5.17 which corrected previous versions very optimistic calculation of pack capacity.

 

[richkae]

My 2 year 2 month old Roadster ( #587 ) only has 17000 miles on it ( I don't drive enough ) - I have just a little over half the miles you do.

I still get 187-189 miles on a standard mode charge and 240 miles on the last range mode charge - the parser shows a pretty flat line where the ESS A-hr hugs the 160 line. The average temperature of my pack over that time is probably 24-26C ( I'm in the cool pacific northwest where most people don't even have AC on their homes )

Charting ESS A-hr vs ESS temperature I think would be very interesting.
Doug ... I think it would be great if you added a smoothed average function for the ESS temperature.

 

[sauhlir]

My almost-three-year-old Roadster (#109) with about 20,000 miles on it (it is my every day car--that's all I drive) has had the ideal range in standard mode drop from 192 miles to 187 miles (not counting the drop with the firmware change). I have definitely noted a correlation between distance driven the day before and final range (lower when I have to charge more). I also believe (though haven't collected the data to be certain) that the warmer my garage is the *lower* the final estimated charge is (I'll get a check of this as we move into winter this year).

 

[AndrewBissell]

Amazing levels of difference between the three 2.x year old Roadsters reported on here.

 

[ChargeIt!]

Sparrow: please tell us your odometer reading ...

And I can add a data point: 2.5 years, 46k miles, 163-165 StdMode.

 

[strider]

I'm at 10 months and 10k miles. I get 189-191 standard mode (down from 193 when new). Car went in for service on 8/5/11 for TPMS malfunction so assumed they updated the firmware then). I've done 3 range mode charges in that time.

Benji, at what rate are you charging? It definitely seems like the lower the charge rate the higher the ideal range. So if you're charging at a high rate, try dropping it for a night and see what happens.

 

[dadaleus]

This is very timely as I was just wondering about this. I'm just under 16k on a 2.0 roadster that I bought in May 2010. It got 187mi in standard mode at first, went up to ~189 for a while, and in the last month it's dropped fast to ~183. This is all charging on 220 volts (various amps, but usually 40). I do notice that when I charge off of 110 volts (at work), it ends up showing more miles--often just over 190. I assume this has to do with the speed of the charge.

 

[Sparrow]

My 1.5 #189 which is a little over 2.5 years old has just under 13,000 miles and the standard charge ideal range varies from 177 to 180 miles.

 

[benji4]

Benji, at what rate are you charging? It definitely seems like the lower the charge rate the higher the ideal range. So if you're charging at a high rate, try dropping it for a night and see what happens.

Hi Strider, I charge at 110V/15A most of the time believe it or not... that's why I'm very suprised to see the sudden drop. However, for some reason when I charged today, ideal miles was all the way back up to 183. The only difference is that it was very cool today. Has been around 30 C or higher lately, but today was more like 22 or 23 C.

For the past month or so, I have not used the car as much as usual, driving it maybe 10 miles or so, perhaps 3x per week. Also, I did not plug it for a few days as I had to park in a garage that had no outlet. I spoke with the dealer who recommends that I go for a long drive or two, charge in range mode once or twice after that, and make sure that the car is always plugged in. They think that perhaps the batteries are just out of balance. If this fails to work, they will do a test on the battery. I'll report back next week on what happened.

 

[benji4]

By the way, it's amazing to see that some 2 1/2 or 3 year old cars have just lost a few miles in range and still show ideal miles in the high 180's -- very impressive! And yet, some of the other cars are down in the 160's which seems like the batteries have degraded a bit fast. With more than 6,000 cells, you'd think that minor differences in the cells would cancel themselves out and the batteries would degrade more uniformly.

 

[Doug_G]

The "range" is limited by the strongest and weakest battery string. The strongest string limits how much you can charge the pack. The weakest string drains first, limiting how much power you can draw. The difference is your range. So battery balance is critical to maximum range.

Last Saturday I did some rather aggressive driving and the next day the car was 6 km lower than usual. So I did a range mode charge and let it balance an hour before driving it. The next day it was back to normal.

Balancing does happen in Standard mode; it just does more of it in Range mode. (So I'm told; Tesla keeps any substantive information about pack management proprietary, so what comes out sounds like black magic.) From previous experience it would have gone back to normal on its own after a few days.

Also if you ever fully charge the car from 120V, you will get a fair bit more Ideal Range than normal. Lower charging power seems to lead to a fuller pack.