40kwh Battery Degradation?

40kwh Battery Degradation?

Has there been any official information about how battery degradation works on the software limited 60kwh battery? For example, if the software limits the battery to 2/3 of the capacity of the battery, there will be degradation. If the software limits to 40kwh, there should be no degradation.

mbergman | November 18, 2013

I went from a fully charged 129 rated at the start of the 5.8 update to 127 upon completion. Time to start emailing upper management, methinks.

I find it fascinating that the theory that rated range drops are due to tinkering with the way rated range is calculated has been repeated so often that it is now accepted as fact by many.

There has been a fairly consistent definition of rated range presented by Tesla reps, that being soc divided by a fixed number determined by the EPA to be typical energy usage per mile. It does seem that the rated range goes down faster than you would expect from that calculation while driving due to the gradual buildup of a reserve so that when you hit zero rated miles you are not dead in the water.

I have not seen any explanation as to why new cars would show the published, unchanged EPA rated range if this calculation has changed. Or course, it is an assumption on my part that they do, but I think it is a reasonable one.

As I believe I have stated earlier in this thread, it is my theory that, if anything has changed, it is that the algorithm to compute soc has become more accurate with software updates. Of course, all of this speculation could be put to rest if Tesla simply published definitions of rated and ideal miles, but I no longer expect that to happen.

Garth | November 18, 2013

With 4.5 I had a max filled range of 227 km (141 mi), as of 2 days ago when I got 5.8 (.22), my range dropped to 218 km (135mi) max.

I can only assume that this sudden drop is to do with the fact no longer lowers at highway speed, thus it must use more power to compensate for the increased drag.

In addition to this the car's vampire power drain has increased significantly from 4.5, in the past 36 hours the car has lost 24 km (16km/day or 10 mi/day) - I have not driven the car since Saturday 11pm.
Previously w/ 4.5 it was losing ~10 km a day.

I reset both consoles yesterday and the burn continues, I set "energy save" off and reset them again this morning and then set "energy save" to back on (it was not sleeping at all, instantly ready when I got in), hopefully that will activate the energy saving.

5.8 (v .22 at least) is not a good release at all...

BarryQ | November 18, 2013

On 5.8, I get 125 rated miles and 142 ideal. Not quite the 160 ideal promised.

Brian H | November 19, 2013

The other variable is buffer (below 0). If that has been expanded, the only place it can come from is "off the top". That would represent no change in actual total charge, though.

larryh | November 19, 2013

On my 40/60, prior to 5, I lost 8 miles from 9PM to 12PM the next day.

After 5.8, I lost 4 miles from 4PM to 12PM the next day.

My rated range right after charging went from 140 to 135. When the car was brand new, the rage was 141.

I have 1527 miles on the car after 6 months.

Captain_Zap | November 19, 2013

Your ideal range readout is more accurate when considering battery performance. My car is a year old this week and the recent update coincided with its anniversary so I monitored the charging closely to see how things changed over the past year.

Keep in mind that I have a P85. When new, the car had an ideal range with full charge of 302 miles. Friday I did the same charge to see how things were going and I topped off at 300 ideal miles. I was quite impressed.

Rated miles and projected miles are calculated differently because of the firmware updates so they are not the best indicator for evaluating overall battery performance. They have been working on refining the readouts.

The point I'm trying to make is that you want to compare apples to apples and the ideal range setting is best tool we have for the job that I have found.

eAdopter | November 19, 2013

I understand the apples to apples comparisons and why some prefer to measure Ideal Range.

However, I'm much(!) more concerned with Rated Range performance than battery performance.

If after a few years the Ideal Range is 300 miles and Rated Range is much less, isn't Rated Range the measurement that will have owners contacting TM to complain?

In other words, I think owners are more concerned about how many miles they can drive. The Ideal Range number is interesting, but not very relevant to me.

Mathew98 | November 19, 2013

@eAdopter - You do have valid concerns about the Rate range. On the surface it does seem like a big drop since your S40 delivery.

OTOH, wouldn't you prefer more accurate Range based on your personal usage versus a more inflated number?

Whenever I ask my wife how long it'll take her to finish getting ready, she would reply in 10 - 15 minutes. We never manage to leave the house for at least another hour after her response.

What kind of answer would you like to hear? Imaginary but sounds good on the surface or realistic but not what you want to hear?

eAdopter | November 19, 2013

To put it simply, I only care about how far I can drive the car when it's fully charged.

Details regarding the algorithms or battery health aren't usefull or meaningful to me and I couldn't care less about them. I'm not even curious.

I only care about the bottom line: How far I can drive on a full charge.

ramtaz | November 19, 2013

Precisely why I purchased the 40 kWh battery , it was advertised at 160!
I have lost 18 miles of range in six months , 7500 miles.
May 29 , delivery was at 147
At this rate , it will be at 111 by Spring.

Brian H | November 19, 2013

A change in Rated Range which is not matched by a change in Ideal Range is not a change in reality, only in the car's interpretation of a given charge, or even a change in the charge reported.

Chuck Lusin | November 19, 2013

I was at 133-135 Rated on 4.5 and now I'm still at 133 (just after charging, or 151 Ideal) in 5.8.
I really think that my true range is about 129 at 289 Wh/mi.
If Ideal is 300 Wh/mi, why can I only go 129 miles at 289 Wh/mi?

Mathew98 | November 20, 2013

Ideal range for S40/S60 is about 270 Wh/m. Ideal for S85 is 300 Wh/m.

Try to match the battery usage and look at the instant mileage graph and you'll see parity between range and ideal miles at 270 Wh/m.

fluxemag | November 20, 2013

I think the bottom line is that even driving below 300Wh/mi, I'm not going to get even the rated range of 126 miles, let alone ideal. And neither is anywhere close to 160 miles. It's not a huge deal for me at the moment, but if this continues it will be. And like eAdopter, I couldn't care less about anything but the actual range I can drive the car. Which as an owner of one, I can say from experience what that is. At 300Wh/mi I can drive about 115 miles.

kingjohn4 | November 20, 2013

@fluxemag -- I'm seeing almost the same as what you're getting. I think we can't go further than 115 or 120 miles at 300 Wh/mile. Which is confounding because at 72% charge cap for the 60kWh, that amounts to: 43.2 kWh, or 43200 Wh. So one would think that you should be able to drive: 43200 Wh/(300 Wh/mile) = 144 miles. But in reality, we're seeing 25 to 30 miles less than that. My lifetime average of over 5000 miles when I go to the Energy Settings is 316 Wh/mile. Even at that, I should be able to drive over 136 miles. But the cap is 20 less than that on real results.

The lack of transparency into this discrepancy is very frustrating and concerning to say the least. It allows the company to always attribute the falling This could be fixed if Tesla would display a "Remaining kWh" metric in addition to rated+ideal miles, so we could see how much charge we have left.

Mathew98 | November 20, 2013

Don't forget about the 15 miles reserve once the car goes below zero.

kingjohn4 | November 20, 2013

Arg, sent my 2nd paragraph prematurely. Should say:

The lack of transparency into this discrepancy is very frustrating and concerning to say the least. It allows Tesla to always attribute the falling numbers to refinements in their algorithms, where it could also be battery degradation. We can't tell because we have no window into the actual charge level. This could be fixed if Tesla would display a "Remaining kWh" metric in addition to rated+ideal miles, so we could see how much charge we have left.

Daytrade71 | November 26, 2013

After the latest update 5.8 My S has dropped from 139 rated to 131 in about two weeks. I was at the service center yesterday and they told me the drop was the way I drive the car. This I don't believe to be correct.. The car has 5000 miles and the kwh used average 301 for the life of the car over 6 months. Why the drop in such a short time? The only real answer I can surmise is the Elon added to the range past zero. Maybe 10 miles that would account for the loss. Several from Tesla ownership have told me that if you drive like a little old lady the mileage will come back. I find this to be not true.

David70 | November 26, 2013


Are you talking about rated range or ideal range? Also, from the numbers you've given I doubt you're doing max range charge. Rated range changes all over the place for me. They're doing a different calculation for rated range now. If you really want to know, do a max range charge with ideal miles set. See how that compares with stated max ideal range stated for you battery pack.

Also, has the weather changed in the last two or three weeks?

Chuck Lusin | November 26, 2013


The 40's don not have the max range charge option, we can only charge to 72%, that is our max (and my standard charge).

Brian H | November 26, 2013

Yeah, 40s are weird, and should be ignored. ;p

murraypetera | March 14, 2014

I brought my 40 in for some issues on being range. They kept it for several day to balance the pack. The also needed to drive off the 200 miles and i would guess cycle it twice. I got back up to about 130 rated miles just after charge stops from what was about 120. Or some 120 ideal to 149.

While this is not yet acceptable, I was also assured an upcoming software release will add some miles to the 40. They did not seem to know how many more.

They are still not changing their position on discounting the unlock to a 60 to "keep thing fair" but this argument becomes less valid over time. I figure with pickup of the car, car rental for 3-4 days, labor, drop odd of the car 2-3 time a year to balance a 40 battery will end up costing them $2000-$3000/year which really does not make much sense.

Now I know the issue and the answer, I intend to have them fix this issue every tire rotation or 2-3 times a year.

Mathew98 | March 14, 2014

So is the battery balancing an acceptable answer for now? It's a 10 miles gain from just 2 full cycling/balancing. What would happen if the SC balance your battery pack even further?

I needed 7 range charges/balancing to regain 6 miles. It seems the SC did a better job with your S40 then I did with my S60.

Daytrade71 | March 14, 2014

Murray: Your right, I think that Tesla will get the word. I am having my MS40 balanced during annual checkup. Down to 128/6000 miles. Hope to get 10 miles back. SC won't commit to a number.

robgoodin | March 14, 2014

Tesla should remove software limitation once a quarter to allow owners to re-balance there batteries. S40 owners are carrying the extra weight of the S60 battery pack which still upsets me a bit. Not only are we software limited we are limited by the physics of extra weight of S60 pack.

ramtaz | March 14, 2014

My 40 is now rated range 122, with 11300miles. I was advised by service that a new update will give us more rated range miles. SOON???? Like the center consoles are on hold??
I also lose 6-8 miles while car is parked at work,about 9 hours, temperature 72 degrees.
No mention from service, about "rebalancing " the battery pack??

mbergman | March 14, 2014

@mathew98, having the service center balance my battery 2 or 3 times a year, letting strangers put over 1000 miles on my car annually, is definitely not acceptable to me. If balancing is the solution, it is both moronic and petty not to allow owners themselves to periodically gain access to the full 60kwh, as @robgoodin suggests.

Of course, max range charging is contrary to Tesla's official recommendations for battery health, so it would be nice if they were updated to include occasional range charges, if that is what is currently required to maintain the range we were promised.

Also would be nice if they gave some indication of when this new software release might be coming, with an indication of what it might be doing to alleviate this problem.

Also would be nice, if after 6 weeks from when Jerome Guillen told me he would look into my concerns, I had received some meaningful information. All I've heard so far (a month ago in response to my post on this forum) is that this issue has been raised with Elon and that they are working real hard to provide a superior ownership experience. Or something to that effect.

I'm not grumpy or unhappy or anything like that. Not me.

Mathew98 | March 14, 2014

@mbergman - I totally understand your POV.

Isn't the official stance to not to keep the car at a 100% charge state for a prolong period of time (stationary)? I don't think there is anything wrong with max charges as long as your car doesn't stay at state for very long.

Max charges are for occasions where a longer trips are expected. I always drive off within an hour of max charging the car. Heck, I even schedule charging to end within an hour of the expected morning drive.

I'd be interested in the upcoming release that would give 40 or even 60/85 owners better estimates for a full tank. That would resolve a lot of griefs regarding the accuracy of the Rated range estimate.

mbergman | March 14, 2014

@matthew98 - "Isn't the official stance to not to keep the car at a 100% charge state for a prolong period of time (stationary)?"

I was curious (haven't looked at the manual for quite a while) so I checked.

Manual says -

For daily driving, charge
between 50% and 90% to improve battery
longevity. Charge above 90% for trips requiring
maximum range.

Nothing, as far as I can see, regarding not leaving it at 100% for too long, so I don't think that's the official Tesla stance.

Appreciate your continuing support.

Brian10 | March 14, 2014

I agree with @murraypetera. The argument to not discount the upgrade to 60kWh does not hold water. Over the next few months, most of us 40's will have owned our car for a year. Those who purchased a 60kWh paid $10,000 more but have enjoyed the used of the longer range for this entire year. 60kWh owner bought their car because they wanted the range. There isn't one 40kWh owner who reserved their car thinking that we'd get a 60kWh battery and would one day be offered the chance to upgrade at a price lower than $11,000.

Also, our batteries are now a year older, more degraded so there is less of a reason to charge us the full pop to upgrade. Honestly, do you really think Tesla will get complaints from existing 60kWh owners if Tesla allow the 40's to upgrade at a lower price, say $5000? No way. They will get complaints from any 40's who have already paid full price for the upgrade but I suspect you could count those people on one hand. Tesla is missing out on an enormous amount of free revenue and the longer they wait, the less free revenue Tesla will receive.

Daytrade71 | March 26, 2014

5.9 just out. I gained 10 miles 127 to 137 rated. rock and roll.

ElectricZo | March 26, 2014

I just upgraded to 5.9 and had 139 rated miles after a charge. Right before 5.9, a full charge was getting me to 120 rated. When I first got the car in July 2013, it was at 147 rated. I have been concerned as it got down to 120. Hopefully I won't see weekly decreases as I have in the past. With the 40, every mile lost hurts more.

Chuck Lusin | March 26, 2014

I'm also getting 140 just after charging with 5.9! Was in the 120-122 rated range in the morning.

This last weekend, I was going to go a 100 mile round trip, but with the hills, I reverted back to the ICE. Even with the site, I wanted to be sure, but now it looks safe to try.

vincent1001 | March 26, 2014

Are you aware the charge limit changed ? Before 5.9, it is 72%. But with 5.9, it looks like 68% now ? But definitely, rated miles got increased.

Brian10 | March 26, 2014

I, too, got a nice increase from 124 to 136 miles. Does anyone know what the cushion is under zero miles? I thought I read that is was about 10 more miles, not sure.

Mathew98 | March 26, 2014

15-17 miles in reserve. Don't tempt fate and get stranded...

BarryQ | March 26, 2014

vincent1001, where did you get that info from?

eAdopter | March 26, 2014

My 40 gained 11 miles (from127 to 138). Prior to v5.9 the car would lose about 5-7 miles overnight while plugged in, and v5.9 has eliminated the overnight loss.

While plugged in, the car/battery can now be heated or cooled without losing miles.

I like the other v5.9 improvements:

Hill-hold works very well. I was surprised to appreciate it so much.

We now have full control of the lowering feature. I anticipate this will increase tire life.

The High and Very High settings are now useful at higher speeds. Good for light snow, dirt roads, etc.

Overall, I'm very pleased with v5.9.

Brian H | March 26, 2014

Be aware the actual range may be unchanged, just reported differently.

vincent1001 | March 26, 2014

@Barryfinn, I see it from charging bar both my vehicle and tesla app. There is a line for max 40/60 can charge. It looks like changed from above 70% to below 70%.

Chuck Lusin | March 30, 2014

I noticed that the range indicator goes green/yellow at 41 miles rated range left now.

Longhorn92 | March 30, 2014

@vincent1001: yes, I noticed the charge limit change from 72% to the 67-68% range as well. Odd that the charge limit was lowered but the rated miles on full charge increased. I do wonder if the buffer below zero miles was reduced as part of the v5.9 changes.

HenryT2 | March 31, 2014

I'll also confirm the increase in range to 135 (from around 121). What a relief! Thank you Tesla for reaffirming my faith. This has been the one area I've been disappointed in. The service manager telling me that "don't worry, the range is still there" was not the satisfactory response he seemed to think it was.

Keep in mind, though it seemed that he was correct, it was almost unusable information. Even IF I wanted to tempt fate by driving under 0 miles remaining, the car's acceleration becomes limited when the charge is almost depleted so I've been limited to low acceleration unnecessarily during those times. I'm curious to see if the acceleration will be limited at the same mileage as before (which I never noted down) or will it be changed to compensate for the additional displayed miles.

trivono | March 31, 2014

Same here. My range went up to 135 from 124. Also hill hold is really nice.