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It's been a year and a half since I last did an update of the data, so it's clearly time to do so. Anyone who wants to be included in the new update should send me their log files. If you haven't done it before, just DM me and I'll let you know how.
If you send me a log and I don't reply it probably went into my spam folder, so also DM me and I'll find it.
If you send me a log and I don't reply it probably went into my spam folder, so also DM me and I'll find it.
JRP3
Hyperactive Member
I think I haven't posted an update since October, 2019 so I'm really overdue.
This includes new data for four cars: 670 (mine), 33, 209 and 1180. The new data for the last two covers about three years.
Mostly, things continue apace with maybe a slight flattening of the curve. At the very least it's clearly not going down at the same rate that it did during the first year when it seemed terrifying. Roughly extrapolating the curve, I'll be at the CAC of a new original battery (154) in about two more years give or take.
You'll notice a big drop in my CAC around 1410 days. That corresponded to a long-ish drive and came after about a year of pretty flat CAC. This is consistent with the algorithm adjusting things downward when it gets a data point from a low state of charge. It had probably been decaying for the year and just giving (somewhat) optimistic values. The drop looks much steeper on the by-mileage graph. That's further evidence that time is the thing that's mostly responsible for loss of range, and I have been driving much less during the pandemic (15K miles in 2019 and 6K in 2020).
Comparing 670 to 33 should make it really clear that the big factor is time. Their CACs are really close to each other each with about 4.5 years on the battery, but 670 has nearly 4x as many miles. Drive your cars! Letting them sit in the garage isn't helping the batteries any.
1810 looks a lot like 33 but with a later install date.
209, however, is somewhat of an outlier on the bad side. I'm not sure what's up there, though I wouldn't be too surprised if it's just rarely range charged, which can cause the algorithm to underestimate the battery capacity.
If more folks send in their data I'll do another update, but if not I probably won't do one for at least 6 months to a year. It's not clear it's helpful more often anymore.
This includes new data for four cars: 670 (mine), 33, 209 and 1180. The new data for the last two covers about three years.
Mostly, things continue apace with maybe a slight flattening of the curve. At the very least it's clearly not going down at the same rate that it did during the first year when it seemed terrifying. Roughly extrapolating the curve, I'll be at the CAC of a new original battery (154) in about two more years give or take.
You'll notice a big drop in my CAC around 1410 days. That corresponded to a long-ish drive and came after about a year of pretty flat CAC. This is consistent with the algorithm adjusting things downward when it gets a data point from a low state of charge. It had probably been decaying for the year and just giving (somewhat) optimistic values. The drop looks much steeper on the by-mileage graph. That's further evidence that time is the thing that's mostly responsible for loss of range, and I have been driving much less during the pandemic (15K miles in 2019 and 6K in 2020).
Comparing 670 to 33 should make it really clear that the big factor is time. Their CACs are really close to each other each with about 4.5 years on the battery, but 670 has nearly 4x as many miles. Drive your cars! Letting them sit in the garage isn't helping the batteries any.
1810 looks a lot like 33 but with a later install date.
209, however, is somewhat of an outlier on the bad side. I'm not sure what's up there, though I wouldn't be too surprised if it's just rarely range charged, which can cause the algorithm to underestimate the battery capacity.
If more folks send in their data I'll do another update, but if not I probably won't do one for at least 6 months to a year. It's not clear it's helpful more often anymore.
backmost
Member
Darn not good news with 209, at least she’s with Gruber now due to a PEM board that fried so hopefully I can get them to do a quick check on the battery before sending it back. I hardly range charge it, very rarely do I need the extra juice
Did you guys see this post in the Facebook group? I thought the owner might post here but it seems like in the meantime Tesla agreed to give him a new pack.
By the way, I have been too busy to pull the logs in recent weeks. However the car has hardly been driven at all in lockdown and would not likely be a representative CAC. Hopefully I can use it in the summer.
By the way, I have been too busy to pull the logs in recent weeks. However the car has hardly been driven at all in lockdown and would not likely be a representative CAC. Hopefully I can use it in the summer.
Range charging makes the CAC go up. If you haven't done it much, it might make the CAC go up really a lot. I'm not entirely sure why, but it's probably a combination of two things: the computer gets data on what happens when the battery gets to high SOC and uses it to revise its estimate; and the battery balances. It's not like the cells get healthier from being charged more.
The flip side of this is that running the battery to low SOC will cause the CAC to decline. While it's possible that this is because something bad is actually happening to the cells, I think it's much more likely that it's just the computer getting more data and updating its estimate.
Well this posted on Tesla Roadster FB page. No, only Model S owner still 
. These prices have gone too north for me. Reposting this as it was buried in comments Roadster 4.0. From Germany with love
. These prices have gone too north for me. Reposting this as it was buried in comments Roadster 4.0. From Germany with love
IslandRoadster
Former Owner of #609
Well this posted on Tesla Roadster FB page. No, only Model S owner still
thanks for posting here. I wonder if Medlock or Gruber would carry and install their battery in the US, if they can produce at volume?
That 4.0 sounds interesting!Well this posted on Tesla Roadster FB page. No, only Model S owner still
My CAC in VIN 33 is now 167.74. A friend with a 1.5 with its original battery just sent to me the photo below showing her CAC to be 177.45 and an ideal range of 201 on a standard charge and 230 if she just switches to range mode after the standard charge. That seems improbably high because a range mode charge would probably result in an ideal range higher than the 240 EPA rating when new. The car has been sitting plugged in some some time now. In that situation can the CAC adaption algorithm go higher than it should?
EDIT: Sorry, there was some confusion. She does have the 3.0 battery, so 177 CAC is reasonable. And still much better than mine.
EDIT: Sorry, there was some confusion. She does have the 3.0 battery, so 177 CAC is reasonable. And still much better than mine.
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A new original battery had a CAC of about 156-157 judging from the data people have sent me. I'm guessing we'll start seeing 3.0 batteries hit that in 1-2 more years.
backmost
Member
Time to do another update since it's been 11 months since the last one.
More importantly, we might have enough time and miles on some of the new 3.0 batteries to compare them to the older ones and see if they drop off as fast.
Please send me your log files, especially if you have a new 3.0 that's been in the car for a while.
My car is at CAC 167 with 5+ years and 62K miles on the 3.0, so it's still better than a new original battery, but by less than 10%.
More importantly, we might have enough time and miles on some of the new 3.0 batteries to compare them to the older ones and see if they drop off as fast.
Please send me your log files, especially if you have a new 3.0 that's been in the car for a while.
My car is at CAC 167 with 5+ years and 62K miles on the 3.0, so it's still better than a new original battery, but by less than 10%.
I have a car with 3.0 battery and I came to the forums to ask why the battery appears to not be charging as high as it once did. Maybe 220 max range with range mode. Glad to see I'm not alone in seeing fast degradation.
The previous owner installed the 3.0 so I don't know when this new pack was installed. Maybe I could contact Tesla and they would know.
The previous owner installed the 3.0 so I don't know when this new pack was installed. Maybe I could contact Tesla and they would know.
spaceballs
Member
220 is pretty low for a 3.0. I'm over 260, and I've got lots of time and miles on mine.
It's entirely possible that you're way out of balance. Look at the max and min SOC from the diagnostic screen. They should be with one or two percent of one another. If they're not then you need to balance the battery, which basically means range charging your car and letting it sit plugged in for a *long* time.
I hadn't range charged much for a good while, and then my car spent a few months at Carl's not plugged in. It's been about 2.5 weeks sitting at range charge and it's still balancing (though it's close to done). I didn't look at what the range was when I started it, but I'm pretty sure I've added more than 20 miles.
You can tell if it's still balancing from the diagnostic screen, too. While it's plugged in at full charge you should see all or mostly 0s on the screen (if it's not plugged in at full charge it will also show 0s but that doesn't mean anything).
It's entirely possible that you're way out of balance. Look at the max and min SOC from the diagnostic screen. They should be with one or two percent of one another. If they're not then you need to balance the battery, which basically means range charging your car and letting it sit plugged in for a *long* time.
I hadn't range charged much for a good while, and then my car spent a few months at Carl's not plugged in. It's been about 2.5 weeks sitting at range charge and it's still balancing (though it's close to done). I didn't look at what the range was when I started it, but I'm pretty sure I've added more than 20 miles.
You can tell if it's still balancing from the diagnostic screen, too. While it's plugged in at full charge you should see all or mostly 0s on the screen (if it's not plugged in at full charge it will also show 0s but that doesn't mean anything).
Yikes. My pack is reading Min: 61% and Max: 74%. I don't know much but this does not look good.
Appreciate the advice on balancing the pack. I also just got my car back from Carl. Please send over any other tips as well. Battery had a lot more range 6 months ago.
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