Power drain while idle (Vampire Load)

[inottawa]

Why don't they just have the car completely shut down when locked and then boot when you unlock the car? Based on the Roadster boot-up time, there is plenty of time from unlocking the door to driving for everything to wake up.

Keep in mind that the plan is to have some other service running to make vitals and other info available wirelessly to your smartphone. Again, it would nice to have these services disabled if you don't care to access that data. I just love the idea of getting the car warmed up before I leave the office to drive home.

 

[eledille]

The Tegra 3 is supposed to be a low power chip - googling seems to indicate 4 watts at full power? Also, every modern chip can change its clock frequency while running. You can get a lot of stuff done these days using less than a watt, all communication with key fobs, proximity sensors etc should be using milliwatts of CPU power.

Is the coolant pump running?

 

[Andrew Wolfe]

I think that your math is a little off. A typical car 12V battery is 50 A-h. Lets say it will last 30 weeks at 168 hr/week. That is 5,040 hours, let's call that 5,000 hours. 50A-h / 5,000hr = 10 mA, which is pretty typical. 10mA * 12V = 120mW

The Prius is notorious for killing batteries in 4 weeks or so. That is because the 12V battery in a Prius is the size of a motor cycle battery (let's say 12A-h) and the "off" current draw is much higher than a regular car. Most Prius owners plan to start (actually put in ready state) their car every 3-4 weeks or put the 12V battery on a maintainer.

Yup. I was sleepy and left out the 24 hours/day in the regular car calculation. That would take my 5W down to 200mw - close to your number. Even more shocking that the Model S is at 125W. I suspect something is being heated or cooled.

 

[Leafster]

I'm more distressed to hear a report that the car is not using "shore power" when left plugged in for several days. I would expect the car to charge to 90% when I plug it in, and to be at 90% the following morning. I would expect it to still be at 90% a week later if it's still plugged in. And I would not expect it to need more power than my SubZero refrigerator to accomplish this maintenance!

That is my concern too. I will guess it starts the charger once a week or so when plugged in.

 

[jerry33]

Yup. I was sleepy and left out the 24 hours/day in the regular car calculation. That would take my 5W down to 200mw - close to your number. Even more shocking that the Model S is at 125W. I suspect something is being heated or cooled.

There would be a variety of pumps that run besides heating and cooling. Brakes and power steering are electrically operated at well, then there's the immobilizer and security system and the transponders for the fob. If they leave everything powered but the screen and lights, 125W doesn't sound like much.

 

[MikeK]

Geez, I hope they wouldn't leave all that running.

 

[jerry33]

Geez, I hope they wouldn't leave all that running.

I believe that's the problem. The goal was instant start. However, there's little doubt that all this can be fixed with software updates. There are three steps in programming:

1. Make it work.

2. Make it work correctly.

3. Make it fast.

Right now we're at about 1.5 or 1.75 with a few items that are >2.

 

[Trnsl8r]

Please forward this on to one of your Tesla contacts as a suggestion. Add dsm363 and brianman as "in agreement" when you send the mail.

Got a response:

I discussed with product planning teams, and passed along your suggestions to them. You will see the software that controls discharge of battery while idle become more and more optimized through future software updates, but, nevertheless, thank you for your feedback.

Please feel free to reach out to us in the future as the need arises.

Have a Great Day,

 

[brianman]

@Trnsl8r - Heh, cool to hear back.

- - - Updated - - -

I believe that's the problem. The goal was instant start. However, there's little doubt that all this can be fixed with software updates. There are three steps in programming:

1. Make it work.
2. Make it work correctly.
3. Make it fast.
Right now we're at about 1.5 or 1.75 with a few items that are >2.

You forgot some steps, jerry33.

1. Make it work.
2. Test it in the wild.
3. Return to step 1 a few times.
4. Adjust specification to refine "correctly".
5. Make it work correctly.
6. Test it in the wild.
7. Return to step 5 a few times.
8. Begin discussions about how to make it fast.

...

 

[jerry33]

I just gave the 5,000 metre view. I didn't bother with the details

 

[stevezzzz]

I'm more distressed to hear a report that the car is not using "shore power" when left plugged in for several days. I would expect the car to charge to 90% when I plug it in, and to be at 90% the following morning. I would expect it to still be at 90% a week later if it's still plugged in. And I would not expect it to need more power than my SubZero refrigerator to accomplish this maintenance!

The Roadster would wake up every 24 hours to top off its charge. I thought the S would do the same; not sure I've paid enough attention to know if it does. But you're claiming the S doesn't even use shore power to offset the vampire draw? That doesn't seem right.

 

[strider]

The Roadster would wake up every 24 hours to top off its charge. I thought the S would do the same; not sure I've paid enough attention to know if it does. But you're claiming the S doesn't even use shore power to offset the vampire draw? That doesn't seem right.

I know that if the charge timer is set in the Roadster it will wake up at the time every 24 hours to top off. Does it also do it if there's no timer set? Maybe once we have a charge timer in Model S it will do the same and top itself off every 24 hours.

 

[FalconNinetyD]

That would be odd that the car doesn't maintain it's charge when plugged in. I plan on taking the car to Vegas. Once I get there, I plan to plug it in, so I have juice to get top the SuperCharger in Barstow for the return trip. If the car charges itself, then loses 40 miles of range just sitting there, even though it's plugged in, that would be a problem.

 

[William3]

I know that if the charge timer is set in the Roadster it will wake up at the time every 24 hours to top off. Does it also do it if there's no timer set? Maybe once we have a charge timer in Model S it will do the same and top itself off every 24 hours.

Yes, the Roadster will wake up and charge every 24 hours, even without the timer set.
Well, at least mine does (2010 model).
I sure hope the Model S does this too.

 

[cinergi]

The model s currently does not wake up and top off - as observed by being plugged in for several days and losing 30 miles of range. I'm sure an update will change this soon.

 

[J in MN]

Remember that model S does not have an explicit storage mode. By not continuously topping off while plugged in, you effectively create a storage mode. Letting the battery sit at high SOC for extended time accelerates degradation. Perhaps it will trigger another charge cycle once SOC drops to 50%. Anyone have time to test?

 

[eledille]

That's a real bummer.

Are we supposed to use range mode whenever we need more than 50% of the range?

I would like a mode where I would tell the car how much range I need and when I need it (e.g. 230km by 08:00, please). Then the car could manage the battery optimally within those limits.

 

[Robert.Boston]

Are we supposed to use range mode whenever we need more than 50% of the range?

Clearly not; Standard charging gives you 85% (?conflicting reports on this) of Range. Even if the "vampire load" draws 10 miles/day, that's only 3.8% of the total battery capacity/day. But, GeorgeB told people at the Toronto store opening that the next software update will reduce this load.

I would like a mode where I would tell the car how much range I need and when I need it (e.g. 230km by 08:00, please). Then the car could manage the battery optimally within those limits.

I agree, but regardless, it should end up with at least a full Standard charge by the selected time. As far as we know, the battery does just fine at Standard SOC. But if I'm doing a Range charge, I really would like it to time the charging to finish off shortly before I'm planning on departing.

 

[Cottonwood]

Clearly not; Standard charging gives you 85% (?conflicting reports on this) of Range. Even if the "vampire load" draws 10 miles/day, that's only 3.8% of the total battery capacity/day. But, GeorgeB told people at the Toronto store opening that the next software update will reduce this load.

I agree, but regardless, it should end up with at least a full Standard charge by the selected time. As far as we know, the battery does just fine at Standard SOC. But if I'm doing a Range charge, I really would like it to time the charging to finish off shortly before I'm planning on departing.

A few facts:

1. Standard charge is 90% of Range charge.
2. Full Range charge is about 265, but I have seen as high as 268 immediately on completion.
3. 90% or 265 is 238.5, but I usally see about 240 at the end of a Standard charge.
4. My UMC at 240V, 40A, gets about 25-28 mph charge rate. One hour of charging on the UMC is about the difference between a full Range and a full Standard charge. It does slow down a little at the very end, near full, so this is a little over an hour. I have not timed it, exactly.

It isn't automagical like we all want, but my practical approach to having a full range charge for a long trip is pretty simple. Plug in the night before in Standard charge mode. When I wake up in the morning, the first thing that I do is go down to the garage and switch to Range charge. By the time I take a shower, eat breakfast, check my e-mail and TMC, etc, more than an hour has passed and the S has finished charging to a full Range charge, and I am ready to leave.

Given that all of this happens in a 12 hour or less period, the Vampire does not have time to dirink much charge. :biggrin:

 

[jerry33]

When I wake up in the morning, the first thing that I do is go down to the garage and switch to Range charge. By the time I take a shower, eat breakfast, check my e-mail and TMC, etc,

That's a workable plan, but if you check TMC you must not leave till about noon (assumes 05:00 wakeup time).