M3P battery KWH capacity test (are my results normal?)

M3P battery KWH capacity test (are my results normal?)

Hello all! I'm the excited new owner of a Model 3 Performance (in blue) and have been nerding out in full force. I used to lease a chevy spark EV and nerded out on that car as well. After driving the M3P for over 2500 miles now, I started to notice my driving range between charges seemed kind of low when compared to the rated ~300 miles. I was keeping the battery between 30% and 80% SOT and would only get ~100 miles of range between there. So I did a 100% to 0% drive cycle over 5 days and got 210 miles. :-( I called tesla customer care to ask about it and were only offered possible variables that hadn't been ruled out. So naturally I'm on the quest to find out the reason for the ~33% reduction in range and am hoping you all will have some insight.

First, I live in southern California with constant mild weather and the car is parked overnight in a garage so I ruled out temperature extremes. Even now in December it is about 70 degrees out. Next I needed to rule out my driving habits so I didn't use WH/mile or the distance gauge as measuring tools. Since I had just driven the car down to 0%, I charged the car and used the vehicles KWH gauge to see how many KWHs it took to fully charge. This was done at home on 240 volt AC. It took 82 KWH. After some research I read that the vehicles onboard AC to DC charger has a loss of ~20%. My old chevy spark had about a 25% loss there so that seemed reasonable. However if the car took 82 KWH then that would mean my battery only took 65 KWH. I then drove the car back down to 0% over several days and got 208.6 miles out of it. The vehicle KWH gauge registered 56 KWH. :-O I scavenged the internet to see if this was normal and couldn't find anyone mentioning this happening to them. I did find a youtube video where someone tested the range of their M3 and they said the vehicle gauge showed 75 KWH used after a single 100% to 0% drive.

Next I needed to explore the parasitic loss phenomenon. I read that the M3 burns about 1% capacity (~.75 KWH) every day. After getting the battery to 80% SOC I let the car sit for a few days. The battery did indeed loose 1% per day over 3 days. Interestingly the car's KWH guage still read 0 KWH used. After losing 3% capacity to parasitic loses the guage should have read 2-3 KWH used. Perhaps the vehicle KWH guage doesn't register parasitic loses? I then tried running the vehicle heater and heated seats while the car sat in the garage until another 3% of the battery had been depleted. The vehicle KWH guage still read 0 KWH used! This surprised me because my old chevy spark registered all energy used on its KWH gauge. Aparantly my KWH gauge on the M3 only registers energy used by driving.

Have you all noticed this too?

Assuming that parasitic loses/climate controls aren't registering on the KWH gauge, then that would mean my car is losing ~30% energy to functions other than the drive motors. I now have about 3300 miles on the car and still notice per my car's KWH gauges that I'm getting ~60 KWH to use for driving per full battery cycle. This is even without using the climate control. With my average 270 WH/mile, that means i'll never be able to expect over 220 miles of driving range. :-( Even with hypermiling techniques I can't seem to get the car below 240 WH/mile and in order to get the rated 310 miles I'd need to get under 200 WH/mile with only 60 KWH of usable capacity to see the rated range. That seems unrealistic considering my old tiny FWD chevy spark averaged about 200 WH/mile. *sigh*

Tesla still hasn't received the carbon fiber lip and badging for my vehicle and i'm thinking i'll need them to test out the battery when those items come in. It's hard for me to accept that the rated 75 KWH battery will only hold ~60 KWH and/or that there will always be a parasitic loss that keeps me below 220 miles of driving range. But perhaps if you all are seeing the same thing then this is normal?

Any insight is greatly appreciated. :-)

jimglas | 11 december 2018

too many letters

M3BlueGeorgia | 11 december 2018

AWD can apparently slightly reduce range, but the 20" performance tires definitely reduce range compared to the 18" tires with aero rims. There are some web sites that show the specific issues.

Charge overnight to (say) 80% and watch your "Wh since last charge". Driving around Metro Atlanta in the summer I was getting better than 240 (LR RWD 18") but now winter has hit, short range driving easily pushes me up into the low 300s.

IHMO: Range really only matters on road trips, because you have a big battery under the floor boards.

Bighorn | 11 december 2018

Too long to follow, but you can’t meaningfully measure capacity over several days. Happy to answer simple questions. You can extrapolate capacity over a single decent drive. Line loss is 10-15% and capacity to travel is 73ish kWh.

hokiegir1 | 11 december 2018

1) It's correct that the kwh used only reports that used driving. There's not really a good "gauge" in the car for vampire/parasitic losses. I do use TeslaFi, which shows how much is lost in each park and sleep cycle, but some aren't fans of it. To each their own. I do like the abundance of data it provides.
2) Wh/m is the best indicator of your efficiency. As you stated, shooting for the 240 range will give you rated range of 310 on a full charge. This is easier for some configurations than others. From what I have seen, 270 is actually pretty decent for a 3P average.
3) Factors that contribute to the vampire/parasitic loss: waking the car by checking the phone app regularly, pre-heating/cooling the car, extreme temperatures, cabin overheat on/off.

Passion2Fly | 11 december 2018

The M3 LR has about 74 kWh usable capacity. The charger has >90% efficiency at 240V. The most important indicator here is the kWh/m gauge. What is your car average since purchase?
Indeed, the vampire drain is not accounted for by the car gauges. The only indication of a vampire drain is the remaining rated battery range.

If you want, you can subscribe for TeslaFi and go to the next level of diagnostics. You're going to get MUCH more information via TeslaFi...

Bighorn | 11 december 2018

You can even get a good estimate without even driving since rate constants are employed.

Rated miles/SOC x 236 Wh/m

Range charge of 310 rated miles/1.0 x 236 = 73.16 kWh

brandonbeckis | 11 december 2018

I apologize for the long windedness. In short I basically think my battery capacity is only getting about 60 KWH, but am unsure if it's just parasitic loss or a mix of the two.

Thank you though it's good to know that the KWH gauge on the car definitely doesn't measure energy usage beyond driving.

hokiegir1 | 11 december 2018

Here's a charging data point for my LR RWD:
11:00 PM - 5:42 AM

6 Hours 42 Minutes

Start - 6 %
End - 90 %

Used - 65.4 kWh
Added - 57.43 kWh

Efficiency - 87.8 %

Avg Voltage - 244.02V
Max Voltage - 247V

Avg Amps - 39.99A
Max Amps - 40A

Est Cost $ 6.54

Rated Miles Added 257.75

Est time to completion 7 Hours 5 Minutes

Odometer 19,340.23

surfpearl | 11 december 2018

@brandonbeckis - Not nerdy enough: change KWH to kWh :)
I'm also in SoCal, same type of car but no range issues, if you want to try any side-by-side testing.

Bighorn | 11 december 2018

I hope you still don’t think it’s 60 kWh based on your flawed measuring technique. It almost certainly is perfectly normal.

nailsmails | 11 december 2018

Don't look at the battery gauge.
Total battery capacity has been suggested as 74.4 kilowatt hours (310 mile X 240 watthours/miles = 74400 watthours)
Look at the kilowatt hours used. If you started with 80% (.8 x 74.4 = 59.52 kWh) just subtract the energy used from the original. I've found its not exactly the same as the gauge.
Charge it to 100% and the drive it down to 5% (Elon said this was fine) and if your usage is 5% off from 59.52 kWh then you will know if the battery gauge is reporting correctly.

nailsmails | 11 december 2018

Typo - it should be 74.4 not 59.52 for that last scenario

CharleyBC | 11 december 2018

One thing you didn’t mention in your lengthy post is your driving style. This is one of the big range factors. In pleasant weather with conservative driving, we get pretty close to EPA range.

hassan | 11 december 2018

Based on a few hundred miles with my M3P this chart seems to be more realistic

ODWms | 11 december 2018

I mentioned on another thread: what’s throwing people is that they’re looking for the EPA numbers at highway speeds and performances. Not going to happen with EV.

EVs’ best numbers come in during city (stop and go) driving, as opposed to ICE mileage (hwy). Your car is hitting at or close to its rated mileage if you’re driving in optimal conditions.

brandonbeckis | 11 december 2018

@hokiegirl1 Thank you for the raw data. That is useful. :-)

@surfpearl Absolutely! Have you watched to see if your KWH used allows for 75 KWH of capacity per full charge?

@nailsmails thats basically what i did. Only I did the full 100% to 0% and got a total of 56 KWH used.

Many comments suggest driving style reducing efficiency. But driving style doesnt effect capacity. I seem to be either getting low capacity or a lot of unknown parasitic loss. Im hoping to see if other M3P owners are seeing KWH output as low as mine.

StealthP3D | 11 december 2018

I'm in southern California too, with the same car, dual motor p with 20" wheels. What you have been describing is consistent with my results. You really going to compare the spark to the m3p? I'm pretty sure to get the performance you will definitely lose range. Hey but if you want better range, get the 18" wheels. Seems everyone keeps trying to compare apples to oranges, even with the model 3s. The M3 performance with 20" wheels will only get about 270 miles range if you hypermile it.

Bighorn | 11 december 2018

Wow—are you just reading every other response?!

shawncordell | 11 december 2018

M3P here. Nope, i’m not seeing the same thing.

surfpearl | 12 december 2018

@brandonbeckis - No, I hadn't watched closely the kWh used figure, but I started a test trial on your behalf :)
15 miles in and so far it matches the expected 75 kWh capacity per full charge. Will keep you posted.

brandonbeckis | 12 december 2018

@surfpearl Thank you! BTW I updated my autocorrect to kWh. All capitals was hardwired into my phone.

@StealthP3D Ok good to know. If you only get ~60ish kWh on your battery too then that points at large parasitic loses. Also the goal isnt necessarily to get more range. The goal is to see if the battery has less than 75 kWh capacity or see if the car has a large amount of parasitic loses. Or both. The spark is the only EV I've ever had so its all i can compare personally to. Of note though it had no measurable parasitic loses and the battery always put out its rated kWh capacity. Albeit a very low 18 kWh.

M3BlueGeorgia | 12 december 2018

There have been a couple of cases where only part of the battery capacity was available, and that required a trip to the SC.

If that is your concern, it was lost in the long missive. If you charge to (say) 80% you should get around 246 miles of EPA range. If you get a lot less, as you imply, setup an appointment with the SC.
Your actual range is irrelevant. What counts is the KWh available to you, which is generally measured in "EPA miles".

Bighorn | 12 december 2018

The Spark didn’t have a BMS that uses a lot of unrecorded energy. You need to measure battery capacity over a single trip if you want an accurate answer. You’re trying to reinvent a fact that was settled years ago. SMH.

StealthP3D | 12 december 2018

@Brandonbeckis, I'm not saying I only get 60kwh. I'm saying on a full charge I will never get 310 miles no matter how I drive and what ever optimal temperature and tire break in, above or below sea level. According to the mobile tech, to keep the battery in good shape, the BMS, battery management system, turns on and off heating and cooling for the battery. That's where you get this 1-2% parasidic loss.

I have a Bolt and it never gets 238 epa miles. But it's shows 3 ranges, high, avg, and low. And the low is pretty accurate. Meaning it shows different estimates of what range you will get.

I'm saying the P3D+ is just less efficient because of the wheels and dual motors and the extra umph they programmed into the car.

ODWms | 12 december 2018

The efficiency difference between the 20” performance and the 18” aero wheels increases the faster and more highway driving you do. City driving (where EVs obtain much more optimal numbers anyway) will produce much, much less of a difference between the two wheel configurations.

brandonbeckis | 12 december 2018

@M3BlueGeorgia, Yup you are correct, I'm thinking my battery may not be holding 75 kWh. Have you noticed on yours if your kWh gauge often doesn't register the full 75 kWh for a full charge? Either by doing a full battery run down or even a partial? As an example I've run my battery down by 50% in a single drive and noticed it used ~30 kWh implying my battery only holds ~60 kWh. It's clear the gauge doesn't register the energy usage from functions other than driving. But at only 1% loss per day (as I've experienced) the ~20% difference I'm seeing doesn't add up.

@StealthP3D, Ah yes I've noticed how inefficient my M3P is when driving. That's no surprise. I regularly refer to the car as an electron guzzler. My spark had the same high/medium/low range estimator as well. The medium was really accurate on it from my experience. I often didn't use it though as following the battery capacity was more reliable for estimating possible range. Have you noticed if your kWh gauge shows all or close to 75 kWh available to use during full or partial drives? An easy way to see is (kWh used) divided by (% battery used) during a drive.

M3BlueGeorgia | 12 december 2018

@brandonbeckis Just look at the kWh. If you think you only have around 60 or so, instead of the mid-70's then get Tesla to remote diagnose and either prove or disprove whether you have the proper sized battery available to you. That kind of big gap is a service issue, unless you bought an MR.

I have an LR RWD with 18" wheels and the kWh computes to around 75, as expected. I can get equivalent of 310+ miles.

Bighorn | 12 december 2018

If you only have 60 kWh capacity, your range charge would show 254 rated miles.

Coastal Cruiser. | 12 december 2018

jimglas said: "too many letters"


meni | 12 december 2018

May just be the heater. Remember SoCal temps drop to the 50’s at night (I live in LA myself), which means the heat will kick in if you set the AC to anything higher. And EV’s lose A LOT of range with the heat on.

FYI I’ve had the exact same issue as you with my P3D (also 20” wheels). I freaked at my horrible 390 Wh/mi after 250 miles. But my A/C was set to 72 with outside temps usually lower. So tonight I dropped the AC to 65 and the fan to 1. My Wh/mi dropped to 311 after 15 miles on flat city roads. Not great, but better. I’ll test again when it’s a bit warmer tomorrow to see if range drops to 300ish (which is what my previous RWD Model 3 averaged).

Perhaps you can try turning your AC totally off and see if it makes a drastic difference. That way you can narrow it down to the AC and/or heater. Would love to know how things progress with you since we seem to share the same issue.

Again I may have the same issue as you. Although I’m not ruling out that it’s the battery, I do suspect it’s just the AC. and I’ve reserved a service appointment to make sure.

Bighorn | 12 december 2018

Service is totally inundated and long term owners are answering your post in the affirmative, that you are describing normal behavior. Please ratchet back the hysteria and cancel your unnecessary appointment so that people with honest to goodness issues can get more timely appointments.

meni | 12 december 2018

@Bighorn I actually agree. Just took my car for a 20 mile city/freeway drive with AC at 64 and seat warmers off and mileage was fine. Cabin was a bit cold but tradeoff is expected. So yeah def the heater. Will cancel my appointment. Happy now?

In other news this P3D is ridiculously fun. Stupid ridiculously fun.

Bighorn | 12 december 2018

I’m content with my P3D as well. My daughter had trouble, unable to supercharge my S last night, so I may end up personally appreciative of there being a service opening, after all. Thanks.

billtphotoman | 13 december 2018

Maybe from December through March we should append the words " NOTE: range drops at temperatures below 50" to the name of the forum? When I owned my Volt the forum moderator had "range drops a lot during cold weather" (or something similar) in his signature. When the first robin of spring arrives I think we will see the "WTF happened to my range" threads die down.