Battery health test

[israndy]

That is smart, doing it at work. I wonder if I could just plug in at one of those Apple Visitor Center chargers during the week and save myself the 100s of kWhs off my electric bill. I wonder if I am still listed as an authorized Apple Employee, I checked a couple of years after I left and my ChargePoint card was still working.

Shame it doesn't let you do it on a slow (25kW) DC charger. The test could take just a few hours at a Harley dealership.

 

[Pianewman]

In my experience, having done this "test" twice, I ran the HV battery down to 5% immediately prior to initiating the test.

IIRC, the rate of charge after it lingered at zero, wasn't linear. It seemed to stop a couple of times, and then resume. It might have something to do with ambient temp? I don't know,

If I do it again, for sure I'll do it at home, and allow more than 24 hours for the test...probably even 48 hours. I'll ignore it until it has arrived at 100%.

YMMV.

 

[JonB65]

Looking at my older post, I realized I did this over a year ago. My plan was to do the test once each year. I also have the Teslogic module installed and that provides battery wear data/percentage. It will be interesting to compare the two. I'll report back after I've completed the test. Could be a few weeks.

 

[Marsh25]

So, the reason mine stalled is because it tripped a breaker. I left it for a few hours, then when nothing changed I went into the shop to check on it. Turns out the 50A welder plug at work was on a 30A breaker. I reset the breaker, set the car to 28A and it completed the test. I scored 89% BTW. The car is a dual motor that is the demo unit for my work (RV dealership specializing in towing with cars, vans, SUVs). It has done 45,000km of mostly highway trips and over half of those towing trailers. So this is the kind of battery abuse that would be more typical of someone that has well over 100,000km.

 

[JonB65]

I'm at 89% with 38,000 miles. A little low, but my 100% range estimate is 290 miles. My perspective is this isn't too bad in real-world use. February 2021 MY AWD. Mixed use: local and highway miles. No towing. I've charged to 100% a few times, but don't let the car stay there. Depart within an hour of hitting 100%, etc.

 

[switlikbob]

I just ran the test on my 2018 Model 3 Performance with 95,xxx miles overnight. The result came in at 84%. I'm not sure if that's good or bad, but I have not really noticed any change to my range in the past 2 years.

 

[israndy]

Usually most of the loss happens early in the batteries life so your battery has probably plateaued before the last couple of years

 

[buddhafree]

I just ran the test on my 2018 Model 3 Performance with 95,xxx miles overnight. The result came in at 84%. I'm not sure if that's good or bad, but I have not really noticed any change to my range in the past 2 years.

It's a good result.
What were your charging habits? State of charge you normally try to maintain, L2 or Supercharger use?

 

[JonB65]

You can also connect to Recurrentauto.com and see how your car compares to other similar vehicles.

Just another data point.

 

[VipinLJ]

Did the test on my '23 MYLR. 6150 miles and 5 months old

 

[wildguess]

'23 MYLR, 8,500 miles, 5.5 months since delivery to showroom, 3.5 months since I got her.

 

[AlanSubie4Life]

Did the test on my '23 MYLR. 6150 miles and 5 months old

View attachment 1044600

'23 MYLR, 8,500 miles, 5.5 months since delivery to showroom, 3.5 months since I got her.View attachment 1044609

People who run this should really post their rated miles at 100% and the results of the energy screen method, at the same time, as cross checks! Inquiring minds want to know.

 

[wildguess]

People who run this should really post their rated miles at 100% and the results of the energy screen method, at the same time, as cross checks! Inquiring minds want to know.

Rated range new was 330 miles, 100% range at the time of the test was 321 mile.
Configuration is "heavy": tow hitch, 7 seats, 20" wheels with Pirelli P Zero All Season Plus Elect tires (the original OEM Goodyears are super dangerous to drive in even light snow conditions, so I got rid of them).
Most of the time I charge to 80% at an L2 public station, supercharge on occasional road trips, may fill up the battery up to 100% if I am leaving within an hour.

 

[VipinLJ]

People who run this should really post their rated miles at 100% and the results of the energy screen method, at the same time, as cross checks! Inquiring minds want to know.

At 100% charge today, it showed 327 miles. I honestly didn't know there was an energy screen method. I've taken a screenshot of the steps so I can do that tomorrow. I assume it might be different though since car is at 69% charge now?

Charging habits.

TL;DR - L

L1 - 35%
L2 - 34%
Supercharging - 31%

Car charges at home on L1 to top up charge (daily driving uses around 12% at most). I usually charge to 80% and sometimes 85%. Also have free L2 charging at work which we use when the car goes below 40%. Usually charge to 85% or even 90% and then charge again when it drops to 40%. When we do longer trips on the weekends, I sometimes charge to 100%. That's because our weekend trips are around 150-200 miles. I've used Supercharging maybe 10 times so far. Only supercharged to 100% thrice while on long trips (or before long trips).

 

[AlanSubie4Life]

At 100% charge today, it showed 327 miles. I honestly didn't know there was an energy screen method. I've taken a screenshot of the steps so I can do that tomorrow. I assume it might be different though since car is at 69% charge now?

The energy screen method is tried and true. I try to link to it whenever I can because I think it tends to reduce confusion around here. And it works.

327/330*79kWh = 78.3kWh

69% will be fine. You'll get reasonably close to the above value, probably within about 1kWh. The only thing that suffers at lower SOC with the method is the precision (extrapolation error). It's still accurate, but less precise.

Given you started probably around 80.5kWh (no way to know but many cars do), you're down about 2.8%. (Down 1% from 79kWh, the degradation threshold.)

Rated range new was 330 miles, 100% range at the time of the test was 321 mile.

76.8kWh. So down about 4.5%. Down 2.8% from the threshold.

Usually charge to 85% or even 90% and then charge again when it drops to 40%. When we do longer trips on the weekends, I sometimes charge to 100%. That's because our weekend trips are around 150-200 miles. I've used Supercharging maybe 10 times so far. Only supercharged to 100% thrice while on long trips (or before long trips).

Since you are both running the battery health test, maybe you care about capacity loss & calendar aging. Obligatory reminder that keeping the car at 55% or below as much as possible (time-averaged) is best. It'll slow capacity loss from aging by about a factor of 2 (maybe a bit less).

So if your schedule & usage allows, just charge to 55% and charge every day.

No worries at all about Supercharging or going to 100%. It really doesn't matter at all as long as it doesn't stay there. Just make sure it's at 55% or below nearly all the time (even lower is better but you get most of the benefit by 55% so it's really not worth worrying about). Really just have to remember that "one simple trick" and not worry about anything else. For many owners it's quite easy to be below 55% more than 90% of the time - and it's not worth worrying about that final 10%.

Lots of data elsewhere on this forum that support these claims.

If you don't care about these things, just use the car as you see fit.

 

[VipinLJ]

That makes sense. I used the formula to calculate from the energy meter and got 78.6kWh. Again. I'm not too worried about degradation. I'll probably sell the car in less than 5 years. But that doesn't mean I'll follow unhealthy charging practices. I usually just follow the recommendation by Tesla but I'll probably keep it around the 60% mark. Like I said. Max daily usage is around 20%. I know when I'll be going on long trips. I have a couple of ICE cars for emergency trips. So yeah. I just wanted more percentage for better performance but I noticed that even at 30% charge, the car still performs very well!

 

[AlanSubie4Life]

I usually just follow the recommendation by Tesla but I'll probably keep it around the 60% mark.

Just for full disclosure note that 55% is substantially better than 60%, per the available data. 60% is on the steep part of the curve of improvement (it's over the cliff). At around 55% (~57% true SOC) it levels off. It's kind of splitting hairs, but it's what the data say and there is a physical reason (graphite peak) that the marginal return on reduced SOC level is so high in that region.

 

[VipinLJ]

Just for full disclosure note that 55% is substantially better than 60%, per the available data. 60% is on the steep part of the curve of improvement (it's over the cliff). At around 55% (~57% true SOC) it levels off. It's kind of splitting hairs, but it's what the data say and there is a physical reason (graphite peak) that the marginal return on reduced SOC level is so high in that region.

So I assume I just charge to 55% now on and keep topping up to 55 every day? I have ZERO knowledge about batteries and its science.

 

[AlanSubie4Life]

So I assume I just charge to 55% now on and keep topping up to 55 every day? I have ZERO knowledge about batteries and its science.

That’s a good simple strategy (if it is convenient - if not, use a higher value).

And don’t worry at all about charging higher, supercharging, etc. Just do those things as you need to, try to warm up the pack before the Supercharger, etc.
100% and high SOC is not an issue at all. Just use it up relatively quickly.

 

[DanDi58]

So I assume I just charge to 55% now on and keep topping up to 55 every day? I have ZERO knowledge about batteries and its science.

Or you could simply follow Tesla's recommendations to charge up to 80% for normal daily driving and don't let it car sit below 20% or above 90% too frequently. Note that this DOESN'T mean you can never go below 20% or above 90%. You can do that all you want. I do it all the time on road trips - I leave my house at 95% and have no issue if I roll into a charging stop at 15%. Returning from Cape May today, I stopped to charge just long enough to get me home at an estimated 10% (ended up at 12%). I plugged in as soon as I got home so the car didn't sit at that 12%. There is nothing wrong with using most of the battery.