How long do the Battery Packs Last?

[CapitalistOppressor]

With just over 30,000 miles the range charge gives 254 miles down from 275.

Everyone should take note that the folks who are seeing significant degradation are very high mileage drivers. I've seen 16k miles, 21k, 30k etc. and we know that almost every car delivered has been in the last 12 months, with most in the last 8.

The answer to this thread is complicated. But it's important to realize that the batteries that Tesla uses are probably good for 3,000 cycles when the battery is experiencing the kind of shallow discharges that most drivers of an 85kWh battery will experience. 3,000 cycles times 265 miles is ~795,000 miles. As far as I know, that testing assumes 60% capacity remaining.

But when you are deep cycling the battery (ie using a large portion of your rated range each day) the number of rated cycles moves closer to 500-1000 because of the additional stress you put on the battery. That's almost certainly why we are seeing high mileage drivers already losing 5%+ of their capacity in the first year.

That is also why the 85kWh battery gets an unlimited mileage warranty, vs 125k for the 60kWh cars. The smaller battery requires deeper cycling for the same amount of driving.

 

[mknox]

But when you are deep cycling the battery (ie using a large portion of your rated range each day) the number of rated cycles moves closer to 500-1000 because of the additional stress you put on the battery.

I wonder what a "large potion" would be considered? I generally charge to 70% and come home at the end of the day with about 35%. I've done a couple of longer trips, and my weekends are generally very low mileage compared to weekdays. I currently have a bit over 12,000 miles (in 6 months) and have only ever done one Range Charge (about a month ago). It came in at 260 miles, but I actually unplugged and left because it wasn't quite finished when I had to leave.

 

[CapitalistOppressor]

I wonder what a "large potion" would be considered? I generally charge to 70% and come home at the end of the day with about 35%. I've done a couple of longer trips, and my weekends are generally very low mileage compared to weekdays. I currently have a bit over 12,000 miles (in 6 months) and have only ever done one Range Charge (about a month ago). It came in at 260 miles, but I actually unplugged and left because it wasn't quite finished when I had to leave.

Not sure. My understanding is that it's potentially worse to charge to 90% and discharge to 10% over the course of a week than it would be to do what you are doing. The total miles driven is only indirectly related to degradation compared to depth of each charge/discharge cycle, at least based on my understanding.

High mileage just makes it more likely that you are relying on deep cycles.

 

[islandbayy]

I have been deep cycleing my battery. I have a 60kw, and I'm draining that sucker quite a bit. I know deep discharging is not good for any battery (Accept Ni-CAD), though so far, I have not lost ANY range. I will be doing a Range charge Friday Night, and will report back what it comes to. I will be about 75 miles shy of 10,000 miles on my 60 kw pack in 3 months 3 weeks a 1 day from delivery.

 

[Kraken]

We've had our car for 3 months. We are just under 4000 miles. We charge to 90% at 40a every night. We typically only use about 40-60 miles a day, so maybe 30% discharge. We have only received one minor firmware update.

we were getting 238 miles originally, now we see about 228 in the morning when we go to work.

 

[brianman]

We've had our car for 3 months. We are just under 4000 miles. We charge to 90% at 40a every night. We typically only use about 40-60 miles a day, so maybe 30% discharge. We have only received one minor firmware update.

we were getting 238 miles originally, now we see about 228 in the morning when we go to work.

I bet you breakfast that 238 was with < 4.5 (93%) and 228 is with 4.5+ (90%). In other words, not evidence of degradation.

 

[CalDreamin]

I bet you breakfast that 238 was with < 4.5 (93%) and 228 is with 4.5+ (90%). In other words, not evidence of degradation.

265 miles * 0.9 = 239 miles

I'm not understanding why you would expect 228 miles for a 90% charge.

 

[dsm363]

It sounds like Tesla in continually refining how they display rated range so comparing rated range from software update to software update might not me as easy as we'd like.

 

[brianman]

265 miles * 0.9 = 239 miles
I'm not understanding why you would expect 228 miles for a 90% charge.

You said "in the morning when we go to work" which implies, to me, that unless you timed the charge completion perfectly ever day you have some vampire drain. With 4.5 vampire drain, only 1 mile overnight loss is better than any TMC report I've heard.

- - - Updated - - -

It sounds like Tesla in continually refining how they display rated range so comparing rated range from software update to software updated might not me as easy as we'd like.

This.

 

[Kraken]

I bet you breakfast that 238 was with < 4.5 (93%) and 228 is with 4.5+ (90%). In other words, not evidence of degradation.

to be fair, I said "in the morning when we go to work" not caldreaming

Our car came with 4.5... (When's breakfast?) We have had one update from one version of 4.5 to the most recent. I'm pretty sure that what we had when we got the car was the second most recent version of 4.5.... Either way, ours has always had only the presets of 80%, 90%, and 100%. We never had a 93% option.

Also, in the 5.0 thread I mentioned my battery loss and how it could be due to vampire drain, software updates, driver habit learning, or degradation. I figured it cold be vampire loss, but then the last few days I was getting up at an earlier time again and it was still about 228. Maybe it's just that when we first got it, we were more likely to joyride and burn more battery resulting in a longer charge time which meant less time between charging completion and getting in it in the morning. That would be solved by allowing for the charging to be controlled to complete at a certain time rather than start at a certain time. I think we've still more recently gone on some occasional longer daytrips without seeing higher results the next day though..... I'll have to test it when I get it back from the service center.

also, while, as I suggested, we may have been doing more joyriding early, overall, our driving habits haven't changed drastically. It doesn't line up with the steady decline I've seen from the high 230s to the low 230s to the high 230s.

and as for the 1 mile loss overnight, I have it set to charge from midnight to 5 am and we leave for work at 0645, so if it did take most of that 5 hours, there isn't much time for vampire loss.

 

[dirkhh]

Also, in the 5.0 thread I mentioned my battery loss and how it could be due to vampire drain, software updates, driver habit learning, or degradation.

(emphasis added)
No, rated miles do NOT appear to include "learning of driver habits". They are based on a somewhat odd energy accounting that has been discussed in detail in that thread.

and as for the 1 mile loss overnight, I have it set to charge from midnight to 5 am and we leave for work at 0645, so if it did take most of that 5 hours, there isn't much time for vampire loss.

Yes, that's why you don't see vampire loss - you hide it with the midnight to 5am charge cycle.

 

[mknox]

I bet you breakfast that 238 was with < 4.5 (93%) and 228 is with 4.5+ (90%). In other words, not evidence of degradation.

Yep. I have noticed significant differences in the Rated Range estimates since 4.5, and the charge percentage to Rated Miles ratio does not seem to be linear. I get something like 149 at 60% (would translate to 248 at 100%), but I got 260 doing a Range Charge, and I actually unplugged before the Range Charge cycle was complete.

 

[dirkhh]

Yep. I have noticed significant differences in the Rated Range estimates since 4.5, and the charge percentage to Rated Miles ratio does not seem to be linear. I get something like 149 at 60% (would translate to 248 at 100%), but I got 260 doing a Range Charge, and I actually unplugged before the Range Charge cycle was complete.

But range 0 is 5% SOC. Check the Energy Accounting thread for all the gory details of how this works...

 

[FlasherZ]

Yep. I have noticed significant differences in the Rated Range estimates since 4.5, and the charge percentage to Rated Miles ratio does not seem to be linear. I get something like 149 at 60% (would translate to 248 at 100%), but I got 260 doing a Range Charge, and I actually unplugged before the Range Charge cycle was complete.

5.0 makes changes to refine them too... basically, don't count on the numbers unless they come from the same release (perhaps even the same minor version in some cases).

 

[mknox]

5.0 makes changes to refine them too... basically, don't count on the numbers unless they come from the same release (perhaps even the same minor version in some cases).

Yes, that was kind of my point. With the different firmware releases, I see different Rated Miles at the same SOC levels, but a full Range Charge still gives me the expected full Rated miles.