Power drain while idle (Vampire Load)

[apacheguy]

Here are my results on 5.8 with Sleep Mode working:

I am at a conference and charged my car to 90% at a nearby charging station, then moved it into the hotel's indoor parking lot at 9:50 PM last night. It was at 215 Rated Miles. It was not plugged in.

This evening at 11:00 PM, I woke the car from my hotel room with the VisibleTesla app. It is reporting 208 Rated miles and 88% SOC.

That is a loss of 7 miles over 25 hours.

A big part of it is determined by the ambient temp when the car awakens to top up the 12 V. I have been running a script to monitor sleep mode and range loss over the last several days. If the car awakens during the middle of the night when temps are sub-40, it must first heat and maintain the main battery before charging the 12V. This leads to considerable range loss.

If, on the other hand, the car wakes up during the middle of the day when the temp is considerablely warmer, the range loss is equally less considerable. Of course, in Canada where it remains cold 24/7 during the winter, you'll be hit by a significant range loss either way.

If Tesla could somehow make the car privy to weather conditions and factor that into the periodic "wake-up" interval then I'm confident that we would all observe much lower range losses.

 

[JRP3]

Why would the car need to heat the main pack to charge the 12V? The heating load from the pack would be much larger than the charging load for the 12V. Plus considering the size of the 12V battery I'd imagine the DC/DC is cycling a number of times through the night to keep it topped off.

 

[apacheguy]

Why would the car need to heat the main pack to charge the 12V? The heating load from the pack would be much larger than the charging load for the 12V. Plus considering the size of the 12V battery I'd imagine the DC/DC is cycling a number of times through the night to keep it topped off.

Any time the car draws power from the main battery the BMS kicks in and will regulate the temp. And yes, the fact that the heating load is so large is exactly my point.

 

[VolkerP]

Still it makes no sense to draw a huge load in order to prepare the battery for drawing a minuscule load.

 

[mknox]

Here are my results on 5.8 with Sleep Mode working:

I am at a conference and charged my car to 90% at a nearby charging station, then moved it into the hotel's indoor parking lot at 9:50 PM last night. It was at 215 Rated Miles. It was not plugged in.

This evening at 11:00 PM, I woke the car from my hotel room with the VisibleTesla app. It is reporting 208 Rated miles and 88% SOC.

That is a loss of 7 miles over 25 hours.

Update:

8:00 AM went to car to drop off luggage: 206 miles

1:30 PM departed with 205 miles.

There were those times I "woke" the car to check on it and again to load my luggage, but total loss over 39.5 hours while parked and unplugged was 10 miles.

This was in an indoor garage where the temp would not have dropped below 60 F. I suppose that's not horrible and I only report it here as another data point.

 

[stopcrazypp]

Why would the car need to heat the main pack to charge the 12V?

That's simply the operational temperature target of the main battery. It's likely unaware of how long the pack would be used. I suspect the other sleep mode update that is promised probably will address this.

Also whether the car is plugged in might play a factor (plugged-in would explain a large load on plug to charge a smaller load that can't be charged via plug).

 

[JRP3]

Seems as if it should be current sensitive at least, so the tiny draw of the DC/DC would not kick in the BMS, since it's a pointless waste.

 

[hans]

Previously I posted that I saw as much as a 6 miles of estimated range reduction in ~6 hours of "sleep" mode on my S60.

Yesterday I returned from an overnight business trip to find my unplugged car had "lost" only 8 rated miles of range in the 24 hours it was parked at the San Jose Airport.

It seems as though the car doesn't deep sleep for a quite a while, but once it does kick in, the vampire drain is greatly reduced.

 

[gg_got_a_tesla]

My experience has been 4-5 miles lost in 12-14 hours and 8 miles altogether in 24 hours with no wakeup calls from the mobile app and with the car not plugged in.

 

[dennis]

My experience has been 4-5 miles lost in 12-14 hours and 8 miles altogether in 24 hours with no wakeup calls from the mobile app and with the car not plugged in.

I am seeing 1-4 miles in 24 hours under the same circumstances (except 85kWh in my case).

 

[Kalud]

I posted in the 5.8 firmware thread, but on my side in somewhat heated garage 18C (64F) over a 14h period I loose absolutely nothing. I charge it initially and then I leave most of the time the car unplugged. I don't have anything that poke the car during that period (phone app or VisibleTesla). The car always goes into (deep) sleep. The car didn't sleep outside in the cold yet, I need to test it out.

 

[dennis]

I am seeing 1-4 miles in 24 hours under the same circumstances (except 85kWh in my case).

One thing I just realized is that Tesla replaced my 12V battery last month. Is it possible that the differing behavior we are seeing is related to the abity of the 12V battery to maintain SOC?

 

[yobigd20]

One thing I just realized is that Tesla replaced my 12V battery last month. Is it possible that the differing behavior we are seeing is related to the abity of the 12V battery to maintain SOC?

according to this article and Elon's tweet, yes it's faulty 12V batteries that cause the vampire loss as the main battery keeps needing to wake up to recharge it. http://www.businessinsider.com/finally--my-tesla-is-fixed-2013-12

 

[apacheguy]

One thing I just realized is that Tesla replaced my 12V battery last month. Is it possible that the differing behavior we are seeing is related to the abity of the 12V battery to maintain SOC?

For those of you with the newer 12V - how often does it wake up to maintain the charge level? Mine wakes up every 12 hours or so and I have the original 12V.

 

[Todd Burch]

Left my car (almost 19K mi) at the airport for several days for the first time, so I now have some vampire drain info to report. I parked on Monday at noon with 129 mi rated. Got back to my car on Thursday night at 9 pm with 110 mi rated. Did not check the car with the app that entire time.

So that's about 5.6 miles of loss per day. Car was sitting at temps between about 25-38°F (not that it matters, as the pack doesn't actively heat itself in these temp ranges).

On the drive home, range indications seemed pretty consistent. I did not see miles magically reappear, nor did I see miles tick off any slower than usual. The range indication seems pretty consistent, even with a cold pack.

 

[apacheguy]

So that's about 5.6 miles of loss per day. Car was sitting at temps between about 25-38°F (not that it matters, as the pack doesn't actively heat itself in these temp ranges).

It does heat the pack in that temp range. I have been collecting telemetry data on sleep mode and can tell you there is a HUGE difference between a night in the 50s and a night in the 30s. The range drops fast when the car wakes up at night to maintain the 12V in temps < 40.

 

[Todd Burch]

Interesting that your data shows that. Goes against the Tesla support person I trusted most! Ugh, why is this car such an enigma?!?

Although why would they heat the pack just to recharge the 12V?!? It's not like it's drawing much power! Seems like a power draw they can eliminate in a future update. No need to heat the pack in that temp range!

 

[hans]

I have been watching the vampire drain my battery for several days while I am away from home.

Definite pattern of ~9 hours of sleep followed by ~3 hours awake on a very regular basis over the past several days. I still need to find out what the car thinks its doing during the extended waking periods. My guess is it is trickle charging the 12V battery but I'm not sure how to prove that.

 

[WarpedOne]

My guess is it is trickle charging the 12V battery but I'm not sure how to prove that.

Mount a voltage logger over 12V battery terminals. Its voltage will go above 14V while charging.

 

[hans]

Mount a voltage logger over 12V battery terminals. Its voltage will go above 14V while charging.

Would a simpler voltage display that plugs into the "cigarette lighter" tell me the same thing?