Battery Leak

Crissa

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The challenge of 48v is the need to step-down the voltage, since existing accessories are 12v.
Yeah, Elon was talking about not using existing accessories when they did this. Power of Ethernet would replace the traditional power harness in the car.

Since all LEDs have to step it down anyhow, to 1.5-3.5v and computer boards tend to run at 5v, well...

-Crissa
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@android04 and @Crissa I really appreciate you guys taking the time to dumb it down for me. It was very helpful. I am a little less paranoid about my EV transition now.
 

Crissa

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You can't get much more dumb than my bike with passive temperature management ^-^

About five years ago, Aerostich took the even smaller version of my bike (an FXS) and commuted with it through a Minnesota winter. https://www.google.com/search?q="zero+below+zero"+blog+site:www.rideapart.com

And with a couple modifications (a jacket for the battery and an electric blanket for when it was parked) it managed it with aplomb.

A Tesla is full of sensors and the octovalve and just does all that stuff for you. Just make sure to plug in so it can keep itself warm at night, a Level 1 (a standard outlet and granny cable) will do that.

-Crissa
 

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Yeah, Elon was talking about not using existing accessories when they did this. Power of Ethernet would replace the traditional power harness in the car.

Since all LEDs have to step it down anyhow, to 1.5-3.5v and computer boards tend to run at 5v, well...

-Crissa
i was thinking of the 12v accessories that normally plug into the cigarette lighter, but those sockets are disappearing in favor of USB ports.

I was also thinking of aftermarket stereos, which aren’t a thing in Teslas. So that leaves us with things like CB radios, Radar Detectors, dash cams, etc., which rely on a 12v source under the dash somewhere. But if Tesla goes this way, the market will follow (“Now Tesla-Compatible!!”)
 

Crissa

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The dash would probably still have 12v, as it's still used in computers to operate their cooling.

But the thing is, any modern CBs and stuff are already taking that 12v and dropping it to five to feed their own transistors. And big trucks and RVs already use 48 and 24v systems because of the limitations of 12v.

-Crissa
 


tidmutt

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That is cherry picking. Which one is worse, being more inefficient when you are in operation (doing something) or being inefficient when you are not in operation? My car is sitting in the driveway a whole lot longer than it is moving. Granted my 18 year old ICE battery looses charge when it is sitting too but a whole lot less.

If BEV battery just need to be heated only before moving, it is fine but if it has to continually consume energy to keep it at a minimum temperature like 50 F during a long winter, I don’t call it efficient. It would be like my ICE gas tank leaking.
Well, not so much cherry picking, just pointing out that the additional waste heat advantage of ICE cars is also a disadvantage. Tesla also uses waste heat it just has less of it.

That is indeed offset by the fact that there is a vampire drain on the battery. What is the magnitude of this though? Various numbers have been thrown around. Why do you care if it makes a BEV just slightly less more efficient than an ICE vehicle? ?
 

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I say we just use standard 12V components with the 48V system . All the lights will be 4x brighter. The power windows will be 4 times faster… Problem solved. :)
 
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Well, not so much cherry picking, just pointing out that the additional waste heat advantage of ICE cars is also a disadvantage. Tesla also uses waste heat it just has less of it.

That is indeed offset by the fact that there is a vampire drain on the battery. What is the magnitude of this though? Various numbers have been thrown around. Why do you care if it makes a BEV just slightly less more efficient than an ICE vehicle? ?
It all comes down to numbers. If the waste is $1 a year to keep the battery healthy, It is not even worth the time we are spending discussing it but if it effectively doubles the electricity used for the miles driven, manufacturers should be more transparent about it especially for folks living in colder climate. That transparency could help with development of new battery tech that needs less care and maintenance.
 

Crissa

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Transparency?

But how much energy it uses is nano-climate related. If it's on the shaded side of your drive it'll use more in the winter than in the summer. If it's on the sunny side maybe it'll use more in summer. And then that'll change from when you drive, what weather you drive through, whether you're on the sunny side of a hill or exposed to wind or...

Your mileage will vary so much that I'm not sure how to even describe it in terms of averages.

So how are you transparent about that?

The car does say how much power it uses. Like your phone, it knows what apps are running and using power. It knows how much power you're using at all times.

My bike doesn't. It doesn't do any of that. It doesn't know how much energy it's wasting to heat the battery in the cold and it doesn't know how much damage I'm doing heating the motor in the summer. It has no way to know. My best bet is to put a meter on my outlet and then compare it with the miles I rode.

How should they be transparent about it?

-Crissa
 
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Diehard

Diehard

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Transparency?
My best bet is to put a meter on my outlet and then compare it with the miles I rode.

How should they be transparent about it?

-Crissa
There is a standard to figure out the power consumption of every EV. There could be a standard for this as well. I am not saying I am smart enough to set that standard but people that make the car and set regulations for it are. Even though EV may not know about heat loss in power transmission to the car, it knows how much came in, Something like a Tesla that collects all kinds of data and knows what all the settings are in every car can pick all model 3s that have default settings. If it can tell how good of a driver you are, it can tell how the car was driven. It knows ambient temperature if not, that info is publicly available for each region and any robot can pick it up. If Tesla wants to, it should be no problem publishing average KWH/mile while driven and as a whole for each month or the whole year based on Zip code or average temperatures. Even if there is no Standard, each company that collects data, can share it (not necessarily in raw format). That is what I mean by Transparency.

If Tesla published something like that for M3 and I bought one, I would do exactly what you suggested in Jan-Feb and compare it to Spring and Summer just out of curiosity and compare it to Tesla's published results. The result may not be as scientific as Tesla could have it because of all the variations I am not measuring but it would be nice to know what Tesla's numbers are before I bought mine.
 


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It all comes down to numbers. If the waste is $1 a year to keep the battery healthy, It is not even worth the time we are spending discussing it but if it effectively doubles the electricity used for the miles driven, manufacturers should be more transparent about it especially for folks living in colder climate. That transparency could help with development of new battery tech that needs less care and maintenance.
Right, that’s my point. Anyway, I don’t know those numbers and I live in a hot climate so I don’t really need to know. How much does it cost to run a heater for a few hours a night throughout winter? Shouldn’t be worse than that I would think.
 

Crissa

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I'm just not sure where to even begin. Maybe like they rate furnaces?

The problem is, the better it manages the therms, the more it's doing, and the more power it's using. So how much of that draw is inefficiency and how much is it doing its job?

-Crissa
 
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ldjessee

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Our current EV is a Nissan Leaf, which manages its battery temperatures about as smartly as Crissa's Zero Motorcycle (which is to say, none). Nissan did equip some top trim models with a solar panel on the rear spoiler to help with phantom drain and to keep the 12v battery trickle charged, but now that it spends most of the time in the garage... it does not really matter.

We lose about 1% every day or two, but I have never bothered to track it, as being a 40kWh pack, 1% is hardly noticeable, it is only after several days the car has been sitting (working from home) that phantom drain is obvious.

It would take a extremely inefficient EV to come close to the inefficiency of an ICE vehicle, even a hybrid. I think Engineering Explained has several videos that calculate the inefficiencies of ICE and EV vehicles (some around towing, but the baseline of when not towing is also calculated).
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