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strider
Active Member
Only during charging. That's the rationale behind the Tattler's "cooldown" feature that starts charging at the lowest rate until the battery temp reaches a target and then reverts to your programmed time and rate.
That is not correct. We're talking about different systems.
The PEM and the motor are air cooled by the small fans at the back of the car. Whenever they ( motor or PEM ) are too warm, the fans run. After a run around the track the fans whirr until the motor and PEM are at a happy temperature.
I don't think the PEM and motor are cooled more aggressively if it is plugged in.
The battery is cooled by the liquid coolant which runs through the radiator with the big fans at the front of the car. Whenever the battery is too hot, those fans will run and the coolant will circulate. Sometimes the coolant circulates without running the fans. The "too hot" level is affected by whether you are charging or not, and whether you are in range, standard or performance mode. Obviously if the car is not plugged in, it doesnt want to waste energy you need to drive to cool the battery more than necessary.
When you are charging, the car will aggressively cool the battery according to your charging mode.
How does the air conditioning fit into your cooling scenario? I believe the coolant runs through a heat exchanger which is cooled by the ac.
The air conditioning shares the coolant with the battery. I would assume that the coolant flows through the battery regardless of what the air conditioning wants. I was told that if the battery is too hot, the system doesnt let the air conditioning run, and it uses all of its capacity to cool the battery.
My best guess would be that if you set your car in performance mode and turn on the air conditioning, it is going to cool the battery as a side effect, so if you want to keep your battery warm - don't turn on the A/C.
I have run my car on the track, and had the motor hit 175C * and the battery 40C.
I have logs for a session last year:
They show that when I came off the track the motor was still about 130C ( when I hit the power limit, I did a couple lower speed cool down laps )
When I stopped, the PEM/motor fans whirred for many minutes, and they did this before I plugged the car in ( they were screaming the entire drive back to the pit area ). I do not know the motor temp when the fans stopped.
30 minutes later when I went to drive it on the track again, the motor was down to 64C
For most of those 30 minutes, the car was plugged in and charging at 240volts 40amps ( either range or standard I dont remember which ) and the battery was down to 33C at the end.
Then I did it again.
*: The highest recorded PEM temp I saw was 49C, the highest recorded motor temp is 141C. It only records once per minute.
When I hit the motor limit warning, passenger glanced at the VDS and saw 175C for the motor.
That indicates that it took ~30 seconds to drop 34C from 175C to 141C when the power was cut in half.
You only get a couple hot laps in a Roadster, I hope the new fans are better.
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The coolant for the battery is separate from the air conditioning in as much as they don't share fluids. In the coolant circuit there is a heat exchanger - battery coolant on one side, AC refrigerant on the other. When the battery needs cooling, it calls for the AC system to start if it isn't running and operates a changeover valve in the high pressure refrigerant line to bleed some refrigerant into the heat exchanger - cooling the battery coolant. Independently, the HVAC system looks at demand from the interior control, the outside air temperature and the inside air temperature at the interior air outlet and at the coolant temperature going back to the battery. From all of that it determines how fast the HVAC compressor should run (the whiring noise above the passenger feet) - that runs from a few hundred rpm to a few thousand depending upon demand. It also monitors the coolant temperature leaving the radiator and activates the auxiliary fans if that gets too hot. This variable speed compressor is a very efficient solution.
The reason that the coolant pump runs all the time is to prevent hot-spots in the batteries and to ensure an even overall temperature measurement.
The reason that the coolant pump runs all the time is to prevent hot-spots in the batteries and to ensure an even overall temperature measurement.
For 2.x cars (not sure about 1.x):
The 3 temps shown at the bottom of the OVMS screen are only updated when the car is 'awake'. The messages are only transmitted on the car's can bus when the car is 'awake', as the controller that sends them goes to sleep to conserve power. This means that they will appear to 'stick' at the last known temperature five minutes after you parked (and left your car standing). Same for the ambient temperature reading, and similar to TPMS.
You can wake up the car by touching one of the car door openers (even if locked) or tapping on the VDS - you will hear the car wake up and the coolant pump start to run. If you do nothing, after 5 minutes the car will go back to sleep (and the coolant pump will stop). The car stays awake during charging, but will sleep five minutes after charging completes.
OVMS has a feature where you can wake up the car remotely. On the temperatures screen, touch on the boot (trunk?) of the car, and it will pop-up a little box asking if you want to wake up the car. That will then send a short (1 byte, actually) can bus message just as if you had tapped on the VDS in the car. You will then get updated temperature readings.
We've got an update to the iPhone App in the works that will show these numbers as gray if the car is not updating them, off if the car has never sent them (eg; tire pressure for a car without tpms), and the normal white if the figures are being updated.
smorgasbord
Active Member
OK, my 11 month old v2.5 is getting Yellow PEM temps and corresponding "Power Limit" Dash lights everyday. Not driving particularly hard, though I do have a hill to climb and I get it there now regularly, but didn't earlier. Outside temps are in the 80's. This didn't happen through the summer last year. I believe the fans are working. I hear at least one fan running a lot of the time.
I'm thinking of accelerating my 1 year service and get this taken care of. I'm also thinking I could drop the bottom pan and clean things out myself. But then, I'm also wondering if anyone has removed the top PEM cover and blown out everything in there as well.
I'm pretty handy mechanically and would not hesitate to do this on any of the my ICE vehicles. Experiences, concerns welcome.
I'm thinking of accelerating my 1 year service and get this taken care of. I'm also thinking I could drop the bottom pan and clean things out myself. But then, I'm also wondering if anyone has removed the top PEM cover and blown out everything in there as well.
I'm pretty handy mechanically and would not hesitate to do this on any of the my ICE vehicles. Experiences, concerns welcome.
Talkredius
Member
Idon't think that this a good idea. The Tesla service normally dismount the complete PEM unit before cleaning. That means, that you have to disconnect motor and battery. You don't have access to the cooling fins from the bottom of the car. I think I remember a thread from cinergi, where he had taken some pictures but don't find it at the moment.
spatterso911
P100DL - Raven
When my fans failed my car acted like yours is except that I also got an error on the VDS. I could still hear the fans but they just weren't going fast enough. Call service. You have nothing to lose by having Tesla come and fix it.
Would I drop the pan and clean out the fans? Yes. Would I open the PEM? No because it will void the warranty.
smorgasbord
Active Member
I note that the battery case has screws that have the seal stuff on them, but the PEM screws do not.
I may drop the pan tomorrow and see how bad the fans are.
As the Roadsters come out of warrenty, it would be nice to see someone like Chiltons publish a repair manual!
Unless you have the recent upgrade (which they mostly only rolled out to cold climate people and I see you're in California), there are two fans, one for the motor and one for the PEM. I think it's entirely possible that the PEM one has failed, but you're hearing the motor one running. Anyway, you shouldn't hit power limits in normal operation, so just take it in and get them to fix it. When I had a problem like this, it was actually the connector in the PEM that drove the fans which failed, and you definitely don't want to be mucking with that.
smorgasbord
Active Member
So, I removed the bottom splash pan and had a look about. It wasn't as dirty as I expected. I blew everything out with compressed air, especially the fans. Since the PEM/Motor had cooled by then, the fans wouldn't run and I didn't know how to get them to run. They do spin freely. FWIW, here's a picture, plus one of the fan's label and since someone asked about the antisway bar, here's the printing on that as well.
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