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I always wondered how much power the BMS used. But I'm not sure that's it. For one, isn't the BMS powered off of the traction battery? Vampire losses occur when the car wakes up and slowly discharges the traction battery to charge the 12 V. Also, the pack shouldn't be continuously balancing 24 hrs a day, right? Surely it will reach a point where all cells are balanced.
For my car, I estimate vampire power draw to be on the order of 1.2-1.5 kWh.
For my car, I estimate vampire power draw to be on the order of 1.2-1.5 kWh.
JRP3
Hyperactive Member
There is also a very small amount of power pulled directly from each module, to power the isolated part of each BMS module monitoring/balancing circuit. This is the case even when all the balancing resistors are switched off. Also the case when the pack is removed from the car and even when the modules are removed from the pack (per the pack tear down thread). While the current amount is certainly very small, it is active 24x7 across each module. Unsure if's enough to really matter though w/r/t vampire drain estimates given here.
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I have enough data with 6.0 to say my vampire drain is between 3-5 miles/day. Nothing seems to have change w/r/t sleep mode and power consumption compared to 5.x. If left alone, the car seems to wake twice a day for 2-3 hours each time. Rated miles decrease on the order of 2 miles per wake up cycle. Furthermore, if we assume that 1 rated mile = 308 watts, then it seems that the 12 V is charged at 200-250 watts.
This graph seems to show the cycling of the 12 V battery (drain and re-charge) over time that agrees with your finding.
12v battery issue explanation, sort of... - Page 8
12v battery issue explanation, sort of... - Page 8
Help! On 5.X, with display energy saving on, i was seeing vampire drain of about 2 miles overnight. My charging typically ends by 10pm or so, so that is reflecting period from 10pm to let's say 10am, or < .2 miles of loss per hour. Unfortunately, I do not have logs of this, since I seldom used VisibleTesla during that period.
Since installing (now 3 versions of) 6.0, I'm seeing loss of .4 miles per hour! Yes, I still have energy savings on. No, I did not check the "always connected" box. Yes, I've rebooted (multiple times).
Is it just me? For those of you using VisibleTesla, can you please let me know what your hourly vampire drain is? Was this a function of software update, or something else? Is it just me, or everybody?
I know from this wonderful forum, that 12v battery charging may be a cause. What else? I've got service visit in a few weeks, and I need enough data to convince Service Center this is an issue - or convince myself it is not!
Since installing (now 3 versions of) 6.0, I'm seeing loss of .4 miles per hour! Yes, I still have energy savings on. No, I did not check the "always connected" box. Yes, I've rebooted (multiple times).
Is it just me? For those of you using VisibleTesla, can you please let me know what your hourly vampire drain is? Was this a function of software update, or something else? Is it just me, or everybody?
I know from this wonderful forum, that 12v battery charging may be a cause. What else? I've got service visit in a few weeks, and I need enough data to convince Service Center this is an issue - or convince myself it is not!
benjiejr
Technogeekextraordinaire
I haven't seen anything discussed specifically about P85Ds regarding vampire drain on these threads, so I figured I would post what I'm experiencing to get an idea if it's normal...
My P85D on firmware 6.1 (2.2.113) seems to be losing about 1 rated mile every 4 hours. It's been this way since I got the car on firmware 6.0. For example, if my car finishes charging in the evening and I don't use it until the next morning (say 12 hours later), then I typically lose about 3-4 rated miles. Are other P85D owners experiencing this?
My P85D on firmware 6.1 (2.2.113) seems to be losing about 1 rated mile every 4 hours. It's been this way since I got the car on firmware 6.0. For example, if my car finishes charging in the evening and I don't use it until the next morning (say 12 hours later), then I typically lose about 3-4 rated miles. Are other P85D owners experiencing this?
vdiv
Chief Grump
Hi, a newbie here without a Model S (yet). 
Would it be wise for Tesla to expose a voltage reading on the 12V battery on the screen and set some thresholds that would trigger a notice to check that battery? It seems that most EV makers try so hard to simplify the instrumentation on their cars to keep the general public from being overwhelmed by data that they intentionally do not include indicators that have been traditional in gasoline cars.
Would it be wise for Tesla to expose a voltage reading on the 12V battery on the screen and set some thresholds that would trigger a notice to check that battery? It seems that most EV makers try so hard to simplify the instrumentation on their cars to keep the general public from being overwhelmed by data that they intentionally do not include indicators that have been traditional in gasoline cars.
Do you have sleep mode enabled and always connected unchecked? FWIW, with sleep mode I lose 3-4 miles/24 hrs.
benjiejr
Technogeekextraordinaire
When I first got the car, I had sleep mode enabled and always connected unchecked, but I changed that to disable sleep mode because I was having problems with my 3G connection and checking the charging status at Superchargers. So maybe my drain isn't that abnormal considering I'm losing probably double what you are, but with sleep mode disabled. Thank you for your input.
Cottonwood
Roadster#433, Model S#S37
There does seem to have been a hardware improvement to reduce Vampire drain between my P85, Sig SN:00037 and my P85D built last 2014. I left them both connected to power while I went on a 1.5 week trip with energy saving on and always connected checked. The P85 Sig was running 6.2-101.36.2, and the P85D was running 6.2-2.4.153. I checked on them a couple of times in the 10 days, but did have charge alerts on so I could see when charging happened.
Both cars started charging when they needed 9 rated miles and replaced the 9 rated miles. The P85 Sig charged 9 rated miles every 1.68 days or 5.38 rated miles per day, and the P85D charged 9 rated miles every 2.43 days or 3.70 rated miles per day. Even with the P85D rated miles being 5% more than the P85 Sig rated miles the P85D has a much less thirsty Vampire.
Put another way, the P85 Sig Vampire drank 1.79 kWh per day, and the P85D Vampire drank 1.29 kWh per day with energy saving on and always connected checked. This is still a very thirsty Vampire, but at least Tesla seems to be slowly taming the Vampire's thirst.
Both cars started charging when they needed 9 rated miles and replaced the 9 rated miles. The P85 Sig charged 9 rated miles every 1.68 days or 5.38 rated miles per day, and the P85D charged 9 rated miles every 2.43 days or 3.70 rated miles per day. Even with the P85D rated miles being 5% more than the P85 Sig rated miles the P85D has a much less thirsty Vampire.
Put another way, the P85 Sig Vampire drank 1.79 kWh per day, and the P85D Vampire drank 1.29 kWh per day with energy saving on and always connected checked. This is still a very thirsty Vampire, but at least Tesla seems to be slowly taming the Vampire's thirst.
I suppose the health of your 12V affects the vampire draw. Are the both near the same age? I only seem to get about 2 years out of one before it starts to lose enough capacity that it attracts Tesla's attention.
Do you have any idea how much extra drain is the result of always connected?
Do you have any idea how much extra drain is the result of always connected?
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