# Tesla cooling system layout



## electro wrks (Mar 5, 2012)

Have you seen this DD into the Model 3 system?: https://jalopnik.com/the-tesla-model-3s-superbottle-easter-egg-is-a-fascin-1830992728

The biggest difference I see with your diagram is the motor is at the end of the circuit going to the radiator and the batteries are on a separate(or partially separate) circuit in the Mod 3. And, of course, the Tesla has the "Superbottle" to control everything. The motor at the end seems to be a common practice. Could this be to give maximum cooling to the more heat sensitive electronics?


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## D&VsEVJeep (Dec 9, 2021)

I highly suggest a separate cooling loop for your batteries and then another for the power electronics and motor. The heater is really only needed for the battery and you don't want the heat from the PE and motor in the battery loop in the summer.


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## Mowza (12 mo ago)

electro wrks said:


> Have you seen this DD into the Model 3 system?: https://jalopnik.com/the-tesla-model-3s-superbottle-easter-egg-is-a-fascin-1830992728
> 
> The biggest difference I see with your diagram is the motor is at the end of the circuit going to the radiator and the batteries are on a separate(or partially separate) circuit in the Mod 3. And, of course, the Tesla has the "Superbottle" to control everything. The motor at the end seems to be a common practice. Could this be to give maximum cooling to the more heat sensitive electronics?


I have not seen that, thank you for sharing! I have not really been looking into Model 3 components and cooling layout because I am not utilizing anything Model 3. I am also not utilizing control valves as, as far as I am aware, there is no non factory (open source) controllers to make them work properly. This would change the plumbing configuration but I am not sure how exactly. I am not apposed to alternate pump placement. It looks like the model three only utilizes one pump? I am not sure if using more than one makes placement less critical or not.


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## Mowza (12 mo ago)

D&VsEVJeep said:


> I highly suggest a separate cooling loop for your batteries and then another for the power electronics and motor. The heater is really only needed for the battery and you don't want the heat from the PE and motor in the battery loop in the summer.


Something more like this? I guessed at the pump location. I think both pumps pulling from the reservoir will be alright?


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## electro wrks (Mar 5, 2012)

It would be better to put the DC converter and charger upstream of the motor. I'm guessing the motor coolant has the highest temperature and possibly heat output of all of the components. It would probably not good to subject electronic parts to this. And, as I'm sure brian will point out if I don't-God help me, this is understanding the charger is normally not operating if the motor is operating.


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## Mowza (12 mo ago)

electro wrks said:


> It would be better to put the DC converter and charger upstream of the motor. I'm guessing the motor coolant has the highest temperature and possibly heat output of all of the components. It would probably not good to subject electronic parts to this. And, as I'm sure brian will point out if I don't-God help me, this is understanding the charger is normally not operating if the motor is operating.


Excellent point! You guys have been such a huge help. Thank you for your input! How's this look?


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## D&VsEVJeep (Dec 9, 2021)

Better. But we will actually use two radiators and really have a separate loop for battery (and cabin heat) and the E-motor/Inverter/DCDC/OBC. The battery then can get heated water (for cold weather), just loop water (when the battery is at a nice temperature but the humans still need heat
) and then cooled water from it's radiator if it starts getting hot. I will use an Arduino to control the contactor A to turn the heater on/off, relays B-D for the loop control for the battery, and relays E-G for the pumps. It will also monitor the flow meters and temperatures to make sure it is all working correctly. Like this:


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## 57Chevy (Jan 31, 2020)

Tesla use several diverter valves to route the coolant based on conditions, i.e. no point heating the battery and then passing the water through the radiator when it is cold outside. Diverter valve keeps battery in its own heating loop. There is also provision for the a/c to exchange heat with the coolant


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## asymptonic (Oct 14, 2021)

Yeah, I had a pretty ugly diagram in another thread of my potential coolant loop, which had a similar possibly over-ambitious design goal: Measure ambient temps, battery temps (via BMS CAN bus), and monitor passenger heating demand, and use a series of coolant valves controlled by an esp32 and automotive relays. I've written the code for it and validated it with a table of temperatures for the various scenarios, but like most of my build, still castles in the sky. 

The hope though was that all scenarios would harvest heat from all heat generating components when needed rather than waste any through the radiator, while needing only a single coolant heater for all scenarios (battery heat, passenger heat). Since then I may be leaning towards a couple of loops and redundant bits in favor of valve switching simplicity.

Previous newb thread: Coolant loop design.


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## asymptonic (Oct 14, 2021)

I see, you're selectively cutting off flow through the radiator but opening it through the heater loop for battery heat/cool. Or alternately bypassing via (c). Pretty clean. Any concerns with B,C,D not responding and/or any way to monitor that? Or phrased another way, is there a 1 input, 3 output flow selecting valve out there so that at worst there is flow the wrong way but no way to be overall closed?


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## remy_martian (Feb 4, 2019)

Coolant loop valve fail is not fatal. You just limit car power or charge rate in that unlikely scenario. The key is having all the sensors in place to do that.

That said, 4 N.O. valves on a common input manifold can do your 1:3 select (1 to any, actually). The 4th valve is for your redundancy, if you must - not necessary, IMO. You can also use N.C. valves to save power, but a fail in the solenoid circuit can mildly screw you - again, you can enter a limp mode.

Flow meters are expensive and a total waste of money, IMO, when you already have open loop speed controlled pumps and temperature sensors. Even when you both make >$200/yr, flow meters are expensive and unnecessary.

By "heat pipe", I'm guessing they mean an electric fluid heater, a _heated pipe_, and not a _heat pipe_.


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## oudevolvo (Mar 10, 2015)

Agree that the second diagram is an improvement Mowza. However, there is still room for improvement.
You do not want to cook your batteries via the waste heat of the motor and inverter.
They operate at different allowed temperatures. For a motor coolant of 70 degrees centigrade is not a problem, for a battery it is.
See also my blogpost on Ideal battery temperature?
So you need to add a way do disconnect the two loops. When needed you can then use the motor/inverter waste heat to warm up the batteries. This is also what Tesla does (but they do more), see my blogpost Using Tesla thermal management system parts.

In my project I even had three separate cooling circuits.

__
http://instagr.am/p/Bw3l5uXHmCU/


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## D&VsEVJeep (Dec 9, 2021)

remy_martian said:


> Flow meters are expensive and a total waste of money, IMO, when you already have open loop speed controlled pumps and temperature sensors. Even when you both make >$200/yr, flow meters are expensive and unnecessary.


Basic flow sensors for Arduino are like $12-15...


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## D&VsEVJeep (Dec 9, 2021)

asymptonic said:


> I see, you're selectively cutting off flow through the radiator but opening it through the heater loop for battery heat/cool. Or alternately bypassing via (c). Pretty clean. Any concerns with B,C,D not responding and/or any way to monitor that?


That's what the flow sensors are for. If I am expecting flow and don't have any, I can flag a message. As a backup to that, the BMS and VCU is also monitoring all the temps of the inverter, motor, batteries, and DCDC/OBC so if anything is too hot (or cold) they will also protect the components.


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## Mowza (12 mo ago)

D&VsEVJeep said:


> Better. But we will actually use two radiators and really have a separate loop for battery (and cabin heat) and the E-motor/Inverter/DCDC/OBC. The battery then can get heated water (for cold weather), just loop water (when the battery is at a nice temperature but the humans still need heat
> ) and then cooled water from it's radiator if it starts getting hot. I will use an Arduino to control the contactor A to turn the heater on/off, relays B-D for the loop control for the battery, and relays E-G for the pumps. It will also monitor the flow meters and temperatures to make sure it is all working correctly.
> 
> That is another excellent point. It makes perfect sense to divide the heat load and have each system not dependent on the other. I really like the use of flow meters from a diagnostic/monitoring standpoint. One would definitely want to know that the cooling system is functioning properly and receive a warning when it is not.
> While I was originally planning on utilizing a standard heater core for cabin heat I came across a PTC heater core from an EV smart car which is very similar in size to the heater cores used in Vintage Air systems. I was going to see if I could swap the core into the Vintage Air unit and use electric heat. I am glad you shared your design in the event I will not be able to do so as it gives me a backup plan. I am not currently versed with Arduino but will be using it for other vehicle systems/features so I will be at some point during this build.


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## D&VsEVJeep (Dec 9, 2021)

I was also looking to replace the stock in-dash heater core with a PTC heater core...but this doesn't help the battery when cold. So, this is why I wanted to utilize a common heated water system for both the battery and the cabin and have the chance to swap loops once the battery is warm yet continue to heat the cabin...


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## Mowza (12 mo ago)

oudevolvo said:


> Agree that the second diagram is an improvement Mowza. However, there is still room for improvement.
> You do not want to cook your batteries via the waste heat of the motor and inverter.
> They operate at different allowed temperatures. For a motor coolant of 70 degrees centigrade is not a problem, for a battery it is.
> See also my blogpost on Ideal battery temperature?
> ...


Thank you for sharing all the info! I did not see the page from your first link but I have seen the page from the second link a few times now. Overall I was hoping for a relatively simple and less complex cooling/heating arrangement but it seems that is not the most feasible or ideal approach for a number of reasons. I really appreciate all of the input/feedback so far from everyone. I feel much more informed an able to take on the task at hand.


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## Mowza (12 mo ago)

D&VsEVJeep said:


> I was also looking to replace the stock in-dash heater core with a PTC heater core...but this doesn't help the battery when cold. So, this is why I wanted to utilize a common heated water system for both the battery and the cabin and have the chance to swap loops once the battery is warm yet continue to heat the cabin...


To make sure I have my head wrapped around this correctly, the reason you chose a standard heater core was because a cold battery running both a battery heater and PTC heater core would not be ideal due to its already reduced output correct? The thought being that the operator would just have to wait before turning on the heat like they would in a gas engine vehicle which would leave the battery running only the battery heater. That makes sense using only one electric component vs two reducing overall demand. 
I do have two questions. Question one, would the battery heater have enough heating capacity to heat both the batteries and the heater core at the same time when demand is the highest (just starting out on a cold day)? Typical coolant temps entering the heater core of a gasoline engine vehicle are around 180-200 degrees F at full op temp. What I don't know is what the actual water inlet temp requirement would be to achieve an ideal vent temp on a cold day. I know there are laws regarding the heat transfer rate to the air passing through the heater core and the resulting air temp that leaves it but I don't know what they are either. I imagine they change based on the temp of the air being pushed into the core. In my case it the HVAC blower is always pulling from inside the cabin where that temp would change as the cabin heated up. This would presumably reduce the required core temp to achieve that same vent outlet temp.
Question two, when the demand for heat is required for both the batteries and the cabin, can your system regulate the flow of that warm coolant to both components? The concern being the water temp requirement for the heater core might need to be higher to obtain an ideal vent output temp. The flow of the higher temp coolant would need to be choked down to the batteries to prevent them from being overheated.


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## D&VsEVJeep (Dec 9, 2021)

So...first...this is just a concept that we will build and check functionality. 

The main idea is that I would like to combine the battery heater and cabin heater using one heating element so I don't need two contactors rated at ~400VDC and 30ish amps (i.e. Gigavac). The idea is to just get the battery up to a nominal temp in cold weather for charging and initial driving. i.e. 10 degrees C using the heated water and then switch over to the bypass loop (no heating or cooling) for the battery (or even the cooling loop later if the temps get too high...but I doubt this...not in our application and in the cold weather). After that I only need the warm water for the heater core for the meat puppets in the cabin.

Our concept is using a 4kw heating element. We will try it and see how well this works. Might be a struggle if the weather is like it is now (-9degF yesterday) but again...we are trying and learning. Maybe with it on and running we don't get enough heat out and I have to switch over to a PTC heater for the cabin...we will see.


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## remy_martian (Feb 4, 2019)

D&VsEVJeep said:


> Basic flow sensors for Arduino are like $12-15...


I wouldn't use anything "Arduino" on a car.


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## oudevolvo (Mar 10, 2015)

Water heaters and PTC heaters have different pros and cons 
Water heater

Often easy drop in for cars with a decent heater and heating distribution
Large heat transfer capacity
- Slow, takes time for the cabin to become warm

PTC
+ Quick heat, direct hot air
- High blower power (thus noise) at highest power

Another advantage of the water heater is that in theory you can use it for both cabin and batteries (if thermal control with fluid).
However. I would not recommend that.
Simplicity with two dedicated devices in my view outweighs the benefits of one device with complex controls and valves.

In terms of power consumption: compared to what the traction motor draws, even two heaters at the same time is not that much kW.


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## D&VsEVJeep (Dec 9, 2021)

remy_martian said:


> I wouldn't use anything "Arduino" on a car.


I agree with you for things like the VCU, BMS, or other critical systems. But this is not a critical system and the integrated safeties and control of the BMS and VCU will take precedence.


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## remy_martian (Feb 4, 2019)

The Bolt pulls about 7kW using its PTC heater in a cold cabin, so I wouldn't say it's trivial. Even that can't get warm enough.

Scavenging heat is the best way on paper, but there's nothing to scavenge when it's 20F outside and you stepped out of the shower ten minutes ago. 

You're right about having to get the water loop warmed up first - takes time.

And a heat pump will be crap at pulling heat from 20F outdoor temps.

Strangely, nobody has mentioned heated seats (electric or liquid heating loop?) and steering wheel...


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## remy_martian (Feb 4, 2019)

^^Again, I would not use anything that is not automotive use qualified on a car. The environment is too harsh to use bench-playtime hobbyist garbage.

I've built too many cars that have left me stranded to know not to use crap pieces, safety critical or otherwise. One tow pays for having used automotive qualified parts. Annoying AF if the heater's not working and you need to get to work.

Your build, your decision. If I saw an Arduino garden hose, or Keurig Coffee Maker, solenoid under the hood, I'd take a pass on buying your $50,000 build.


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## asymptonic (Oct 14, 2021)

I think the only issue with a development board is having a solid power supply that can handle awful vehicle power, (ideally hardware) watchdog functionality, waterproof & EMF blocking enclosure. The good dev boards aren't really that sensitive to an automotive environment. That said, someone must market a microcontroller for this application...


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## asymptonic (Oct 14, 2021)

Indeed.


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## Mowza (12 mo ago)

oudevolvo said:


> Another advantage of the water heater is that in theory you can use it for both cabin and batteries (if thermal control with fluid).
> However. I would not recommend that.
> Simplicity with two dedicated devices in my view outweighs the benefits of one device with complex controls and valves.


I was actually thinking that initially, having one heater for each system. Figuring out the electrical accommodations for a second water heater would be the only bridge to cross. The use of the heater for the HVAC would be minimal as a majority of the time the vehicle I am building would be a fair weather driver. The only exceptions would be the crisp dry fall days and any cool dry spring days. I may just go that route. Thanks for your input!


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## Mowza (12 mo ago)

remy_martian said:


> I wouldn't use anything "Arduino" on a car.


I am all about hearing others experiences with certain products and avoiding any pitfalls. Do you have bad experiences with Arduino products on things you have built? Do you have any recommended alternatives?


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## remy_martian (Feb 4, 2019)

asymptonic said:


> I think the only issue with a development board is having a solid power supply that can handle awful vehicle power, (ideally hardware) watchdog functionality, waterproof & EMF blocking enclosure. The good dev boards aren't really that sensitive to an automotive environment. That said, someone must market a microcontroller for this application...


Nope. 

Commercial semiconductors are not rated for operation below 0C. Or above 70C. 

Our techs would troubleshoot circuit packs using freeze spray - a complete shock of ignorance epiphany when you hit the shop floor to train them with your wet behind the ears engineer-degree qualifications 😂


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## remy_martian (Feb 4, 2019)

Mowza said:


> I am all about hearing others experiences with certain products and avoiding any pitfalls. Do you have bad experiences with Arduino products on things you have built? Do you have any recommended alternatives?


It's not "Arduino products". It's using components not intended for automotive applications. An Arduino board is not designed for auto use. Developing using the Arduino IDE and prototyping using an Arduino board is ok. Putting an Arduino board in your engine bay (ICE present or removed) would be bad practice. 

Buy stuff designed for use in cars, where possible. If not, design it for use in cars using automotive components (not that many here can do that). If you must use commercial-rated crap, keep it in the soft environment of the passenger cabin, though it too can be brutal until conditioned. 

Lastly, duct tape and baling wire, live with the bad choices.


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## asymptonic (Oct 14, 2021)

Except the one I posted rated from -40C to 150C. But don't go out of your way to read anything tonight.

Edit: and yes, there is a difference between the mc and a dev board, which is just that, a dev board, not for actually placing in the finished product, before you jump to conclusions.


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## remy_martian (Feb 4, 2019)

lol..."indeed"

TBH, I didn't click because it was unclear what you were indeeding.

That post will be easy for someone to search and find from the main page 😂

Yes, like the one you posted.


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## Mowza (12 mo ago)

asymptonic said:


> Except the one I posted rated from -40C to 150C. But don't go out of your way to read anything tonight.
> 
> Edit: and yes, there is a difference between the mc and a dev board, which is just that, a dev board, not for actually placing in the finished product, before you jump to conclusions.


As the saying goes, you learn something every day! That's good to know there are components with different ratings. I will be sure to pay close attention to that if I go that route. Thanks for the info to both Remy and Asymtonic!
There is also the option of laying out the Arduino board and once one has it functioning the way they want it, take it to an electronics manufacturer and have them make a more hearty and compact version. It will have a cost for sure but hey, maybe it can turn into the first open source controller for coolant valves!


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## oudevolvo (Mar 10, 2015)

Fully agree on that Arduino stuff is not a true automotive solution. On the other hand, it helped me in my hobby project a lot. I learned a lot and it worked (to a certain extend). I used two Teensy 3.6's. And even though I embedded it with all relevant protections such as TVS diode's, gate drivers and DC/DC with wide voltage input range I managed to kill one once it was installed in the car. Still don't know why. Trigger was the alarm being triggered while not being connected completely so perhaps it was being powered via the alarm status feedback analog signal, who knowns?

__
http://instagr.am/p/B_RZk62nu2i/
Still don't know why. Another event where the Teensy tripped is when a connected DS18B20 sensor failed. All OK secondary systems in a hobby environment.

Nowadays for customer projects (my hobby turned into a business) I stay away from those solutions and prefer components with ECE-R10 certificates.
But there are options in between.
For example the Controllino CONTROLLINO – 100% Arduino compatible PLC | Industry-ready hardware


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## asymptonic (Oct 14, 2021)

Mowza said:


> There is also the option of laying out the Arduino board and once one has it functioning the way they want it, take it to an electronics manufacturer and have them make a more hearty and compact version. It will have a cost for sure but hey, maybe it can turn into the first open source controller for coolant valves!


There is a half-way point, services like OSHPark will fabricate a PCB with your design on it for not too much. As mentioned above, it's really about the ancillary components feeding your microcontroller for power protection and the like. And as myself and D&V note, _not_ using your own electronics to run anything safety related.


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## reiderM (Dec 30, 2020)

What coolant heater are you using?

In my own build I've looked at the OEM ones but of course they're all made to run at 400v. I have a 100v Hyper9, so that's not an option for me unfortunately. Unless I make a boost converter for just the coolant heater...

Any thoughts here?

For what it's worth, I don't think the coolant in an EV gets nearly hot enough to heat the cabin on it's own just from battery/motor/electronics heat. And heating liquid is far less efficient than heating air. Ceramic heating element is the way to go for cabin heat, its instantly hot and very simple.

Any thoughts here?


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## 57Chevy (Jan 31, 2020)

reiderM said:


> For what it's worth, I don't think the coolant in an EV gets nearly hot enough to heat the cabin on it's own just from battery/motor/electronics heat.


Yes. Even with an ICE that has a faulty thermostat which drops the temp to 60degC, the heater almost stops working completely. Needs 80C to be a useful cabin heater, anything less and it'll need a massive radiator inside. 

There are plenty of generic PTC heaters available for different voltages, much more efficient for cabin heat.


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## remy_martian (Feb 4, 2019)

reiderM said:


> What coolant heater are you using?
> 
> In my own build I've looked at the OEM ones but of course they're all made to run at 400v. I have a 100v Hyper9, so that's not an option for me unfortunately. Unless I make a boost converter for just the coolant heater...
> 
> ...


Lucky you on the voltage. All kinds of appliances heat water at what is essentially 110VDC...

Do it right and you can make tea or coffee as your cabin coolant 😂

Keurigs are cheap and have solenoid valves as well...

Some demand domestic water heaters' 110V immersion elements may be more suitable for heat output, though.

note: this is not an Arduino component being suggested 😅


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## floydr (Jun 21, 2021)

Coolant heater that runs off 12v 30A







not sure how hot it will heat the coolant. Three VW coolant glow plugs 10A per glow plug.

later floyd tdi coolant glow plugs normal glow plugs burn out if left on for more than 15-30 seconds


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## remy_martian (Feb 4, 2019)

360W of heat is effectively going to a heatsink (the heater core), which heats the cabin. Seems puny in terms of delivered energy and 12V comes from a lossy DC-DC converter vs directly from the battery.

An interesting experiment would be to run them as a series string at 100V while they are immersed and there's coolant flow - should be around 3kW. The details of how to connect them on the negative pole are left to the reader...


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## Tremelune (Dec 8, 2009)

The complexity in this thread is making my head spin.

My Leaf-powered Mini has a small coolant loop, and the pump failed months ago. I didn't even notice. The only time temps ever got over 60°C was when I was literally running up a mountain in the summer. My batteries don't get warm to the touch unless the cells are under 3.7V.

Granted, this is an 1800lb car, and the Leaf batteries don't get any of the coolant running through them, but I'm not light on the throttle, and it gets hot in Los Angeles. I would be very surprised if the stock radiator of an ICE car couldn't _easily_ handle the heat output of an electric motor and its batteries for street driving. Like when my pump was working, I was using a Prius inverter radiator. Now the water isn't even _forcibly flowing_ and it's okay.

I would run a single loop with a single pump and a single radiator: tank -> pump -> batteries -> inverter -> motor -> radiator (or really, whatever layout is simplest). If it proves inadequate, add complexity.

Batteries get hot from high-speed charging, and inverter/motors get hot from long high-speed runs (like minutes/hours on a highway). What am I ignorant of? Under what scenarios are other conversions overheating where mine is not?

PS - Getting rid of heater cores is one of the best things about ditching internal combustion...Heated seats go a long way, and a supplemental HV heater/defroster will take care of the rest...rapidly.


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## asymptonic (Oct 14, 2021)

I think the complexity is battery _warming_. In LA you don't get low temperatures that often, so sluggish batteries probably doesn't come up often. Then, once you decide you need battery warming, you are trying to be efficient about the source of heat. 

I think I agree about single radiator though, that was my initial plan. If the loops are completely independent you'd need more than one, but I think I'm okay with forgoing some modes in order to simplify that part.


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## Tremelune (Dec 8, 2009)

My motor swiftly gets to maybe 35-40°C and then plateaus for the most part. Given that, and maybe an inline "T" thermostat to bypass the radiator, would normal driving get the battery up to "room temperature" in adequate time?


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## remy_martian (Feb 4, 2019)

You also don't need a cabin heater in L.A. unless you go up to Mammoth regularly. But, yes, your loop makes total sense for modest charging rates.

Do you have regen and if so, what's the max "charge" rate you can absorb during braking?


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## Tremelune (Dec 8, 2009)

Hard to say about the regen...I like a fairly strong regen for one-pedalin', but I know that it's significantly less than full throttle draw.


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## 57Chevy (Jan 31, 2020)

One thing to consider if recycling an ICE radiator is the dT is far less so there is no point having multiple rows of tubes/cores. The first core has the highest dT to the air, then any cores behind it are cooled by hot air and are next to useless. Big areas of single core with a shroud and ducting to eliminate reversion are the most efficient way of cooling electric. Also AC radiators are best kept separate as they'll heat the radiator make it useless. Tesla puts two AC radiators in the front fenders and one coolant radiator in the middle.


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