-25 celcius has eaten 66% of my range

[eloder]

Coming from a Leaf, the cold alone isn't the biggest factor. Things like headwinds I find to be the biggest impact, followed by snow or crappy road conditions.

My ~25-30 degree temperature range has varied from just a 15% reduction of my normal battery, down to something like a 40% reduction, even without heater use.

 

[AWDtsla]

Coming from a Leaf, the cold alone isn't the biggest factor. Things like headwinds I find to be the biggest impact, followed by snow or crappy road conditions.

The Model S has a much smaller drag area than a leaf. So winds should affect it less.

 

[ThosEM]

Maybe start with the diagnostic screen that shows the implemented coolant loops in the center console.

Perhaps you could say how to get to this screen? I'd like to catch it in different states of operation...

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Here you go...

View attachment 111795

By no means do I claim to fully understand this diagram, but it looks to me like the motor cooling loop can be switched via the valve at upper right between the exterior radiator and the interior cabin radiators, reducing the need for resistance heating once the motor and inverter warm up. That is consistent with the patent diagram in that area, no?

 

[jerry33]

Perhaps you could say how to get to this screen? I'd like to catch it in different states of operation...

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By no means do I claim to fully understand this diagram, but it looks to me like the motor cooling loop can be switched via the valve at upper right between the exterior radiator and the interior cabin radiators, reducing the need for resistance heating once the motor and inverter warm up. That is consistent with the patent diagram in that area, no?

The two blower icons (closest to the Parallel box) labeled 25% and 30% appear to indicate that both hot and cold can be provided to the cabin fans as required. I don't see any other interpretation for this. (Unless those icons don't indicate blowers, but something else).

 

[MP3Mike]

The two blower icons (closest to the Parallel box) labeled 25% and 30% appear to indicate that both hot and cold can be provided to the cabin fans as required. I don't see any other interpretation for this. (Unless those icons don't indicate blowers, but something else).

I assumed that they were coolant pumps.

 

[AWDtsla]

I assumed that they were coolant pumps.

They are coolant pumps.

The diagram does not show battery coolant going to the cabin, period.

 

[ThosEM]

I'm congenitally doubtful of anyone who is so confident of their knowledge that they shut out contrary evidence. Mknox claimed there is no thermal loop though the cabin, and so did AWDtesla. Yet both the patent diagram and the diagnostic screen clearly show such a loop. How else would air conditioning of the cabin be implemented, by cooling the resistance heater?

The diagnostic screen could certainly use some interpretation. It's the first time I've studied it and I'd be very interested in having each of the items on it identified by those who are more familiar with it. Also, I'd like to know how to access it.

 

[AWDtsla]

I'm congenitally doubtful of anyone who is so confident of their knowledge that they shut out contrary evidence. Mknox claimed there is no thermal loop though the cabin, and so did AWDtesla. Yet both the patent diagram and the diagnostic screen clearly show such a loop. How else would air conditioning of the cabin be implemented, by cooling the resistance heater?

The diagnostic screen could certainly use some interpretation. It's the first time I've studied it and I'd be very interested in having each of the items on it identified by those who are more familiar with it. Also, I'd like to know how to access it.

You're reading the diagram incorrectly, confusing the refrigerant loop with the coolant loop. I think it's pretty clearly laid out, except for the loop graphic not indicating the contents. The only place the two loops intersect is in the chiller, which is after the thermostatic expansion valve. Only refrigerant enters the cabin loop. There's two expansion valves, one for the chiller, one for cabin AC. Coolant is not what goes into an evaporator, or expansion valves.

 

[mknox]

I'm congenitally doubtful of anyone who is so confident of their knowledge that they shut out contrary evidence. Mknox claimed there is no thermal loop though the cabin, and so did AWDtesla. Yet both the patent diagram and the diagnostic screen clearly show such a loop. How else would air conditioning of the cabin be implemented, by cooling the resistance heater?

A refrigerant loop enters the cabin for the cabin a/c evaporator, but no glycol loop enters the cabin (as it would in a conventional ICE for the heater core).

 

[ThosEM]

You're reading the diagram incorrectly, confusing the refrigerant loop with the coolant loop. I think it's pretty clearly laid out, except for the loop graphic not indicating the contents. The only place the two loops intersect is in the chiller, which is after the thermostatic expansion valve. Only refrigerant enters the cabin loop. There's two expansion valves, one for the chiller, one for cabin AC. Coolant is not what goes into an evaporator, or expansion valves.

The valve in the upper right controls whether the coolant loop goes through the external radiator at the top, or apparently (at least to me), though the cabin heater where the refrigerant also flows in parallel. It does look a bit ambiguous, but do you know of any other function that bypassing the external radiator could serve other than to dump heat in the cabin?

Attached is the graphic when cooling is being done by the AC (found in a Youtube video). Under those conditions, the motor cooling loop is directed to the external radiator, but when calling for heat in the cabin, it seems the valve at upper right could be used to get as much as possible from the motor-inverter waste heat before activating the resistance heaters.

 

[AWDtsla]

The valve in the upper right controls whether the coolant loop goes through the external radiator at the top, or apparently (at least to me), though the cabin heater where the refrigerant also flows in parallel. It does look a bit ambiguous, but do you know of any other function that bypassing the external radiator could serve other than to dump heat in the cabin?

Attached is the graphic when cooling is being done by the AC (found in a Youtube video). Under those conditions, the motor cooling loop is directed to the external radiator, but when calling for heat in the cabin, it seems the valve at upper right could be used to get as much as possible from the motor-inverter waste heat before activating the resistance heaters.

Valve in upper right only diverts glycol through front radiator when passive cooling is enabled, has no impact on cabin. This diagram should really clear things up for everyone. Note the blue loop for refrigerant, it does not mix with the other loops. Chiller is a refrigerant/glycol heat exchanger.

 

[green1]

do you know of any other function that bypassing the external radiator could serve other than to dump heat in the cabin?

How about not dumping the heat at all and keeping it in the drivetrain? at cold temperatures you don't want it through an external radiator because you want to keep it, that doesn't mean you're dumping it in the cabin instead. You'll notice that the alternate path shown does not include a radiator/heater core at all.

I'd like to think that after Tesla specifically stated that they used the waste heat from the drivetrain to heat the cabin that it was true. But we've just seen no evidence of it, and considering how many other things Tesla have said that turned out to be false, I think this is another one of them.

 

[mknox]

How about not dumping the heat at all and keeping it in the drivetrain? at cold temperatures you don't want it through an external radiator because you want to keep it, that doesn't mean you're dumping it in the cabin instead. You'll notice that the alternate path shown does not include a radiator/heater core at all.

I think they do keep all the heat in the battery/inverter/motor loop when it's cold enough. Likely at any time they're dumping heat overboard, you wouldn't want it in the cabin anyway (i.e. it's summer).

I'd like to think that after Tesla specifically stated that they used the waste heat from the drivetrain to heat the cabin that it was true. But we've just seen no evidence of it, and considering how many other things Tesla have said that turned out to be false, I think this is another one of them.

Yeah. I was told this when I was reviewing the Beta car by a Tesla engineer myself which led to a lot of later confusion. I think they found, after keeping the huge battery pack warm with "waste" heat, there just wasn't enough for the cabin anyway.

 

[AWDtsla]

Yeah. I was told this when I was reviewing the Beta car by a Tesla engineer myself which led to a lot of later confusion. I think they found, after keeping the huge battery pack warm with "waste" heat, there just wasn't enough for the cabin anyway.

This, basically. The problem isn't the heat energy itself, it's more the maximum temperature of the glycol loop. They probably discovered you couldn't accomplish cost-effective heat transfer to the cabin this way. Maybe with a gigantic heat exchanger that you couldn't fit behind the dash.

 

[ThosEM]

How about not dumping the heat at all and keeping it in the drivetrain? at cold temperatures you don't want it through an external radiator because you want to keep it, that doesn't mean you're dumping it in the cabin instead. You'll notice that the alternate path shown does not include a radiator/heater core at all.
.

This doesn't make sense. To interrupt the external radiator cooling, one would simply put a thermostat in to interrupt the flow or shut off the circulating pump. One would not put in a separate line to nowhere controlled by a valve. It doesn't wash.

IMHO there is ample evidence that the heating load on the resistance heaters drops to essentially zero when the motor gets warmed up, even when it is quite cold outside. So I believe Tesla actually did this right.

OTOH, they didn't implement a reversible heat pump, which is a real shame, considering that the LEAF has that feature.

 

[AWDtsla]

IMHO there is ample evidence that the heating load on the resistance heaters drops to essentially zero when the motor gets warmed up, even when it is quite cold outside. So I believe Tesla actually did this right.

I have seen none of this evidence. The draw drops hugely from the initial 6.6kW sure, because 6.6kW is just MASSIVE. That's not evidence that it gets assisted by other means, it's just the thermostat working.

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You're going to make me dismantle my car over some wishful thinking aren't you?

 

[Barry]

The draw drops hugely from the initial 6.6kW sure, because 6.6kW is just MASSIVE.

Not compared to what the motor draws on a launch :smile:

Also, at 400V, it's only about 15A

 

[AWDtsla]

Not compared to what the motor draws on a launch :smile:

Also, at 400V, it's only about 15A

We're not talking about launches. We're talking about range. 6.6kW adds 35% to cruising consumption of a 70D at 65mph.

 

[brkaus]

This doesn't make sense. To interrupt the external radiator cooling, one would simply put a thermostat in to interrupt the flow or shut off the circulating pump. One would not put in a separate line to nowhere controlled by a valve. It doesn't wash.

IMHO there is ample evidence that the heating load on the resistance heaters drops to essentially zero when the motor gets warmed up, even when it is quite cold outside. So I believe Tesla actually did this right.

OTOH, they didn't implement a reversible heat pump, which is a real shame, considering that the LEAF has that feature.

They would still want the circulation within the battery to avoid hot/cold spots and ensure consistent temperature throughout. So I don't think turning off the circulation pump would be a good idea.