Model S fan builds database of battery degradation data

Batteries do degrade over time, and unfortunately most EV models haven’t been on the road long enough to provide a lot of data, so there is still much to be learned about how quickly capacity loss takes place.

Plug In America has conducted battery longevity studies for the Nissan LEAF and Tesla Roadster, and is in the process of doing the same for the Model S.

In the Netherlands, Tesla enthusiast Merijn Coumans is working on a parallel project, updating a file of owners’ data on a regular basis, via the Dutch-Belgium Tesla Forum.

http://chargedevs.com/newswire/model-s-fan-builds-database-of-battery-degradation-data/

The interesting thing to note here is that even though the Rav and MS share VERY similar drivetrain..

1. We charge up to different capacities.. (seems normal charge is 90%) and full is 100%.. well.. 4.150v So 90% is good enough for Tesla and longevity.

2. We charge at 1/4c (assuming a good 250v/40a source) and 25a current into the battery. These packs are not feeling ANYTHING. :lol:

3. Charging with Tony's JdeMO... you'll see barely over 1c/120a on the best units out there. Most are 44/25kwh (115a/50a) so the Rav's battery are just humming along. Look at what Tesla is pushing into theirs :shock:

If the MS owners are getting these #'s after supercharging... the future's bright for us!!

JasonA said:

The interesting thing to note here is that even though the Rav and MS share VERY similar drivetrain..
1. We charge up to different capacities.. (seems normal charge is 90%) and full is 100%.. well.. 4.150v So 90% is good enough for Tesla and longevity.

Click to expand...

I am under the impression it starts at 80% when new and gradually is charged more and more to sort of keep the same range so after a few years it might charge up to 90%. Just my interpretation of things I read here.

2. We charge at 1/4c (assuming a good 250v/40a source) and 25a current into the battery. These packs are not feeling ANYTHING. :lol:

3. Charging with Tony's JdeMO... you'll see barely over 1c/120a on the best units out there. Most are 44/25kwh (115a/50a) so the Rav's battery are just humming along. Look at what Tesla is pushing into theirs :shock:

If the MS owners are getting these #'s after supercharging... the future's bright for us!!

Click to expand...

Remember that the BMS of the MS warms/cools the batteries all the time, where as the rav4 only does that when driven or when charging.
We have a slightly worse BMS than the MS.

Yes, our Panasonic cells degrade, like all batteries do.

We can measure degradation with a "normal charge and observing the SOC%.

When new, it's about 83%

With degradation, that SOC% will go up. It seems that the amount that the SOC% rises is one half the actual degradation, so that 30% cell degradation would be a 98% SOC on a normal charge.

I'm at about 14-15% degradation at 48,000 miles.

More info came available today

Battery Degradation Level In Tesla Model S Only 5% After 30,000 Miles?

on average, the data show that Model S batteries have only degraded by around 5% after ~30,000 miles (50,000 kilometers).

http://cleantechnica.com/2015/05/18...vel-in-tesla-model-s-only-5-after-30000-miles

Our BMS is not as efficient as tesla model S but we shouldn't be too far behind.

Is there an app to check degradation in our RAV4? As a comparison my Leaf is approaching 28k miles and reporting 97% capacity which exceeded my expectations. And we charged to 100% for the last year.

Phatcat73 said:

Is there an app to check degradation in our RAV4? As a comparison my Leaf is approaching 28k miles and reporting 97% capacity which exceeded my expectations. And we charged to 100% for the last year.

Click to expand...

How do you know it is "97% capacity"?

If you want to know degradation, make sure that the battery is at room temperature, then:

1) Fully charge vehicle (extended) with the J1772 port (not CHAdeMO)
2) Battery must be near room temperature
3) Turn off cabin climate control with "OFF" button
4) Disconnect the 12 volt battery negative cables and leave off for several hours minimum (overnight is ideal)

Next day:

5) Reconnect 12 volt battery
6) Hold foot on brake and press START button with key fob nearby
7) Energy gauge will show Full (16 illuminated segments) and "LO" on the GOM
8) Wait for navigation unit to complete its start up
9) Press START with brake pedal depressed a second time
10) The displayed range is "RATED RANGE" at 3.5 miles per kWh

11) Divide this Rated Range by 146 to get usable battery capacity compared to new.

Example: 142 rated range / 146 = 97.2% battery capacity from new

TonyWilliams said:

If you want to know degradation, make sure that the battery is at room temperature, then:
1) Fully charge vehicle (extended) with the J1772 port (not CHAdeMO)
2) Battery must be near room temperature
3) Turn off cabin climate control with "OFF" button
4) Disconnect the 12 volt battery negative cables and leave off for several hours minimum (overnight is ideal)
Next day:
5) Reconnect 12 volt battery
6) Hold foot on brake and press START button with key fob nearby
7) Energy gauge will show Full (16 illuminated segments) and "LO" on the GOM
8) Wait for navigation unit to complete its start up
9) Press START with brake pedal depressed a second time
10) The displayed range is "RATED RANGE" at 3.5 miles per kWh
11) Divide this Rated Range by 146 to get usable battery capacity compared to new.
Example: 142 rated range / 146 = 97.2% battery capacity from new

Click to expand...

Extended charge,
had 12 volt battery disconnected for 5 hours.
66 degrees Fahrenheit in the garage
16850 miles on the odometer
145 miles range after power on
145/146 = 99.3% ?!
That is not bad at all!

fromport said:

16850 miles on the odometer
145 miles range after power on
145/146 = 99.3% ?!
That is not bad at all!

Click to expand...

Very impressive !!!

You told me the same thing Tony last week down in SJC and mine came out to 149mi (21,890mi) but I'll test tomorrow before I go to the meet.

FYI.. my unit showed 154 new at Carson. So is 154 my base??

http://hostthenpost.com/uploads/9232761e9e6680bf43b0c8c9e19d8ba3.jpg

I finally had a chance to do this myself, and... well, I guess I got the magic RAV4 EV. No check EV errors, a working heater *and* 42kWh on the battery after 32.5k? My 2012 came new with 170 miles on the odometer or so - perhaps it was Elon's demonstrator?

I suspect JasonA's suspicion is correct and 154 is the number to divide by, at least for us. That's the number I vaguely remember from a battery pull early on, and that would put me at 95.4% capacity after 32.5k miles, which is right in line with what other Tesla owners are reporting per the article.

I should note my (drafty, downstairs) garage was around 65-66 since I didn't want to heat up the entire house to get it all the way up to room temperature proper, although I doubt that would have this positive an effect. On the first boot, the GOM went from Lo to --- to 148, and then jumped down to 147 after the second boot.

The good news is that either way, things are looking good!



[Edit to fix obnoxiously large image.]

What firmware do you guys have?

eschatfische said:

I finally had a chance to do this myself, and... well, I guess I got the magic RAV4 EV. No check EV errors, a working heater *and* 42kWh on the battery after 32.5k? My 2012 came new with 170 miles on the odometer or so - perhaps it was Elon's demonstrator?

Click to expand...

This, quite obviously, is not the method I specify. I've had 207 on the GOM before. That means absolutely nothing.

I suspect JasonA's suspicion is correct and 154 is the number to divide by, at least for us. That's the number I vaguely remember from a battery pull early on, and that would put me at 95.4% capacity after 32.5k miles, which is right in line with what other Tesla owners are reporting per the article.

Click to expand...

That puts all my cars at significant degradation on the "first day" then.

I should note my (drafty, downstairs) garage was around 65-66 since I didn't want to heat up the entire house to get it all the way up to room temperature proper, although I doubt that would have this positive an effect. On the first boot, the GOM went from Lo to --- to 148, and then jumped down to 147 after the second boot.

Click to expand...

After watching the CAN bus for the past almost year, I can tell you that the SOC% (a calculated value) changes between 96.5% and 99% after a full charge. I'm reasonably confident that the GOM default calculation has to be some number. My observations from many, MANY disconnects of the battery is 3.5 miles per kWh.

So, 146, 147, 148, sure. I don't have an answer for 154, nor have I ever seen that.

TonyWilliams said:

What firmware do you guys have?

Click to expand...

I never got the sticker, but they did specify that I got the separate power management and propulsion system updates that were part of the same bulletin as 1.3.83. The nav system was also updated to VB503150.

TonyWilliams said:

eschatfische said:

My 2012 came new with 170 miles on the odometer or so - perhaps it was Elon's demonstrator?

Click to expand...

This, quite obviously, is not the method I specify. I've had 207 on the GOM before. That means absolutely nothing.

Click to expand...

Odometer, not GOM. Per above, my RAV had been driven quite a few miles before I bought it, most likely just test drives. I was jokingly speculating that mine has been abnormally reliable and had low degradation because it was used as Elon's demonstrator and thus received special attention, more reliable parts, etc. before I bought it.

That puts all my cars at significant degradation on the "first day" then.

Click to expand...

I agree that that's as unlikely as my RAV having no degradation. Doubtlessly there is a difference in the way that initial GOM value has been calculated, either across firmware versions or due to other conditions. I did follow your instructions to the letter short of the small temperature variation.

So, 146, 147, 148, sure. I don't have an answer for 154, nor have I ever seen that.

Click to expand...

There are a couple of other people who have reported 154 as the original value at the dealer, here and here. Of course, that could just be a coincidence of normal GOM craziness, too, but it seems like a common number.

Kohler Controller said:

If the 12V battery is disconnected for ~5-7 hours, does that mean I have to reprogram my radio stations (which I would dread), or does the system have enough memory/capacitance to keep it stored during this test?

Click to expand...

I suspect the radio saves the important things in NVRAM to persist across power losses. I didn't lose my stations, cell phone pairings or equalizer settings, but I did lose some more trivial settings, like the map display mode, the volume of voice notifications and random play modes. Strangely, my charge schedule was retained, but the default charge mode was reset to always charge immediately after the battery pull.

Well, that was my point. 154 from the dealer doesn't mean anything, unless they just reset it (which is unlikely... the procedure isn't reset, then leave parked all day, or test drive, or move the car, etc).

I will add that I have disconnected the battery to my three cars DOZENS of times, over numerous firmware updates (from the earliest).

If I take the oldest car, with the most degradation, and drive it at my standard test speed of 100km / 62moh ground speed, it will go almost EXACTLY the rated range.

TEST DRIVING PROTOCOL - dry, hard surface level road with no wind or cabin climate control with new condition battery at 70F, no elevation changes, "out-and-back" or loop course to compensate for any wind

So, if the car is new, it will bang out 146 miles and the rated range will be 146 under the prescribed conditions.

If the rated range is 135, it will go 135.

Forgot to post this on Sat morning before I left... 1 hr unplug before I left for the meet but it was 54* outside so it wasn't warm. I'll do it later next week when it's 78* supposedly

As for the FW version.. it was the latest since they just did the motor. I'll check here in a bit under the hood.

Yes, 144 / 146 = 98.6%

Very believable. I have no idea where the 154 number came from earlier. It will be interstiing to see the number with a warmer battery.

this is interesting. i think i've seen this number (the extended range estimate with a completely reset GOM) a couple of times since my vehicle was new (once when the 12volt battery in the car *died* and another time after the replacement of the motor at the dealer because of the hum issue). I didnt realize there was a procedure to "get it to do that".

I can tell reasonably well what the battery pack is like (within a KW or so) due to my drive to the mountains (which requires a charge which i almost always get a the same charger). So i know the starting and ending condition and how much i had to add in the middle.

So far i've found that my driving style (whether there's a lot of traffic, which helps range) etc. has a MUCH greater effect (several KW) than anything regarding the battery. I'm not sure there's enough battery degradation in 2+ years/33K miles of ownership to notice except by doing a test like this.

My "charge time" varies from a little over an hour (in the summer with limited A/C to about 2 hours (dead of winter, no heat on but 30-40F). On a 6KW charger that's about 4.5 KW of "difference" on a drive that consumes around 43-44KW of power. (This is the charge i want to replace with JDEMO btw)

Just checked #2496:

22,000 miles

17 months in service

142 miles / 146 = 97.2%