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Battery drain Model S vs. Roadster

We all know the Model S has issues with battery drain while not in use, thus I decided to test how much for both my Model S (Sig #26) and my Roadster (#404). I did this test while on vacation (8 days and 2.5hrs) with both cars in the garage unplugged, garage temp about 60 degrees, here are the results:

All in miles and "rated range"

Start Range Ending Range Total Usage Avg Per Day
Model S 227 83 144 17.8
Roadster 167 159 8 .987

The Model S is a great car but this has to be fixed, its pretty stunning that the Model S would consume ~18 miles of rated range per day while idle!! This is why you would not take it to the airport for any trip more than a few days unless there was a charge station. Also for completeness (state of battery) the Model S has 7,800 miles on it since September 2012 and the Roadster has 26,300 miles since April 2009.

Re-format

Model S
Start Range 227
End Range 83
Avg use per dat 17.8

Roadster
Start range 167
End range 159
Avg use per day .987

I wish I had known this before I went on vacation 14 days ago and did not leave the Tesla S charging, only to find a completely unresponsive car on my return yesterday. The driver window was down, which apparently happens as the car looses final energy from battery. Tesla will service tomorrow, which will likely involve jump start the 12v battery after popping the nose cone, and then hopefully recharging the main battery. I will know better in the next few days, but I also suspect our car lost at least 15 miles of rated range per day. We live in Southern California where weather should be an issue. Still love the car, but seems there should be a fail safe to prevent this from happening.

The parasitic loss is amazing especially when you figure out how many kW that is over a year. I have runs several long test on my S (VIN4311) and consistently get 270Watts per hour loss at 60-65 degrees. It looks like you were doing a bit better and only losing about 240Watts per hour. This past week I installed V4.3 and the loss dropped to 160 Watts per hour. I was skeptical at first since it wasn't mentioned in the release notes but the improvement is real. Still not great but certainly an improvement.

@ wbuchi | APRIL 7, 2013: The driver window was down, which apparently happens as the car looses final energy from battery.

This is cause by the 12V battery being low, not the main battery pack, although who knows what state your main pack is at.

Thanks for the comparison, Andrew. I've found the same issue while leaving my S in the airport garage for a week. I was thoroughly surprised at the loss of charge!

I'm quite certain that the folks at TM are busy working on the fix to the sleep mode. Let's hope it comes soon.

Yesterday I stopped into a Tesla sales office to pick out some colors for the model S I just ordered. The sales guy said something I'd heard a different sales person say before - that the car can sit with a 50% charge for six months. It was the exact same verbiage both times, so clearly they're getting that from somewhere.

Is that just a complete fabrication?

It's one of those "My Tesla Rep said" statements:-) It is almost certain that the Model S would brick if you let it sit that long. The Vampire loss is a real issue and contradicts what Tesla claims in t heir sales pitch.

Always keep the car plugged in!

Well what they are likely referencing there is the "lower power mode" that supposedly goes from 1% loss a day to 4% a month (the electronics effectively shut off), so it would greatly extend the time before the battery hits 0.

That said, it sounds as if the 1% per day is not accurate at the emergency power mode shuts on at 5% (or it is supposed to).

So is that "lower power mode" ever coming back? And, for those who had used it previously, how did it work in terms of usability? Ie, did you have to wait a long time for the car to come back on line, or...?

@stimyg - yes it is coming back (or so we believe) The problem was that TM identified certain scenarios whereby the car might not be able to wake up.

In my experience there was virtually no wait time for the car to come back online when it was in 'sleep mode'.

Nick, how many miles per day did you lose back when sleep mode was available? I'm also losing about 10 miles per day currently.

I learned this from the first responder video: The 12 V battery is necessary to complete the electronic circuit necessary for the large battery to provide current to the car. If your 12 V battery dies after a prolonged period of standing with the car not connected to a charger, I have to believe that further losses from the main battery are eliminated since the circuit is effectively cut. Maybe this is the "low-power" mode that saves your battery from ultimately bricking. By the way, Elon confirmed in the same Twitter post about the Sarah Palin comment that "bricking" is covered by the model S warranty. Nevertheless, the vampire load issue needs to be ultimately fixed.

Sleep cut it to about 2 mi/day. Emergency mode super-sleep is another deal altogether, intended to protect the main pack. You might need a 12V boost or replacement to re-awaken it, though, from "coma-sleep".

Is it also normal to lose charge while plugged in? I have my S on a 110 circuit while we are away. I watched it charge on my phone app to 240 miles, and now two days later the car is at 229.

@AndrewB

Thanks for the factual data that put everything in perspective. I agree that this drain needs to be addressed. I also agree that there should be zero drain of any type while the car is plugged in. That is the way my computer and phone work and I do not understand why the car is not the same. I hope that TESLA does come up with a solution in the near future. In the mean time we must understand that we are on the leading edge and learning as we go.

Elon stated that the sleep mode will be re-enabled soon. I said the shipments to Norway will not have this issue, so I don't know if they are solving the problem for Norway shipments with a software or hardware modification?

I = he in previous post, sorry.

It seems like they have had a awfully long time to fix this rather glaring problem. Elon should personally look into this and start busting some heads until it's fixed. Sooner or later it's going to start generating bad press if it's not addressed.

If these were ICE vehicles, the equivalent of vampire drain would be a leaking gas tank. If that was the case, you bet the problem would have been solved quickly. So why is it different because the "leaking" energy is simply in a different form?

I'm having the same issue. Went on vacation one week after buying my Model S and I've been monitoring the battery drain using the mobile app-I'm losing 9 miles of range every day. I don't remember being told during my delivery lesson to leave it plugged in when gone but sounds necessary if it's going to drain that fast!

It's not a big issue right now due to the limited Superchargers for cross country travel. Once people start to take longer road trips and have limited options to stay plugged in at night the noise will grow louder unless it gets fixed. I like the leaky gas tank analogy - not something that should go without a solution soon.

They are working on a strong sleep mode to dramatically decrease "vampire" energy lose. I expect the update fix to be released not too long from now.

If these were ICE vehicles, the equivalent of vampire drain would be a leaking gas tank. If that was the case, you bet the problem would have been solved quickly. So why is it different because the "leaking" energy is simply in a different form?

Probably because "leaking" battery charge isn't a fire hazard.

The comparison isn't to a gas tank leak, it's comparable to "idling" IMO. The Model S is never truly OFF.

I thought the drain will be fixed by the patch last week 4.5 (v1.33.61), but it did not. My tesla is still draining at about 15 miles a day.

My analogy to the battery drain would be that the car has 2 100 watt light bulb on at all time. What could possibly need that much power when the car is idle?

Elon's comment was that 4.6 would solve this. Not there, yet.

I was about to buy a showroom Model S with 700 miles on it when I learned of this issue. Its not a big issue, but the fact that it has been unresolved for so long gave me a little too much unease to reach the decision to purchase. My loan was approved and I was about to do it. Now I think I'll wait a year. But I will be one of you lucky Model S owners one day! Currently I drive a 2011 Volt, and driving electric is definitely the only way to go, in my humble opinion. More power to Tesla, I hope its a huge long-term success.

But if 4.6 fixes this and it is due soon, you may not have to wait very long!

Vampire drain is not a big issue. It costs about $10/month in extra electricity usage.


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