Just what is 'vampire drain' energy been used for?

4868 Views 25 Replies 12 Participants Last post by donald, Apr 12, 2018

gzoom

Discussion Starter · Mar 14, 2018

Last two nights we've been away from home so not plugging in the car.

Monday night parked up with 50% SOC, in the morning it was down to 45% - followed by an option to 'update' the software even though the car had no access to Wifi.

Last night parked up with 30% SOC - turned off 'always on', passive entry, turned on energy save, in the morning 29%.

So clearly when you 'turn off' some of the options the vampire drain drops dramatically, which makes wonder what on earth the car is doing to use so much energy in 'normal' mode. Is it something to do with it constantly reporting back to base , and software updates etc been pushed??

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gzoom

Discussion Starter · #21 · Apr 1, 2018

Car left for a total of 8 days (about 188hrs) with everything turned off.

SOC dropped from 65% to 59%. Assuming 72kWh usable

Worst case would be 65.4% down to 58.5% - 7% or about 5kWh consumed in 8 days.

Best case would be 64.5% down to 59.4% - 5% or about 3.6kWh consumed in 7 days.

Either way, the vampire drain seems to be not too massive when idle. Ideally it would be 0% loss, but given the fact the car seems 'always' online regardless of what option you go for, the energy use isn't horrific.

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Russ

· #22 · Apr 12, 2018

I see your phone charge has increased from 68% to 99%. Could the 6% vampire losses be due to you charging it up from the car?

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Simon Mac

· #23 · Apr 12, 2018

@Russ now I have a mental image in my head of @gzoom phoning Tesla's support desk to ask about his vampire drain:

Technology Electronic device Telephone Hand Finger

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Renaissance

· #24 · Apr 12, 2018

gzoom said:
20% when parked up last night at 530pm, 20% this morning at 8am, but dropped quickly to 19%. Arrived home with 11% tonight, in theroy enough charge to make it to the weekend but Im a chicken so plugged in just now.

It's not a great idea to let it drop so low if you can help it, anyway. Better for the long-term health of Li-ion batteries to charge whenever possible and not let it drop below ~20% for significant periods!

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gzoom

Discussion Starter · #25 · Apr 12, 2018

Renaissance said:
It's not a great idea to let it drop so low if you can help it, anyway. Better for the long-term health of Li-ion batteries to charge whenever possible and not let it drop below ~20% for significant periods!

Normally charge doesn't drop below 50% before been plugged in. Had a few days without access to easy home charging so thought I see just how low I dare leave it.

But now have E7 meter finally installed at home, 6 days in our day/night split is 40/166kWh.....currently working out at 3p per mile in fuel

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donald

· #26 · Apr 12, 2018

SOC indication is not an exact science. Battery behaviour is more like cookery than digital processing. Maybe the BMS just thinks about it a bit more and decides you didn't have that much in the first place? Would probably be better to underestimate than overestimate, but Tesla always like to side with the 'optimistic'. Ampera BMS would often kick its SOC up a notch after it had sat for a while and found a bit more in there than it thought.

So maybe it is just a % or so with the rest just being a SOC correction? You will never be able to tell, there is no way to measure battery SOC directly.

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