DIY Electric Car Forums banner
1 - 20 of 22 Posts

·
Registered
Joined
·
26 Posts
Discussion Starter · #1 ·
I saw on one website that there is a IN and OUT side for the Tesla batteries cooling system. It did not say which side was in or out. I do not see any markings on the batteries. Does it matter what side the coolant comes in on? If so, what side is in and what side is out.
 

·
Registered
Joined
·
926 Posts
From what I've seen, the Tesla S and Y modules have thermistors on the most negative and the most positive cells in the module. In the stock temperature monitoring system, the direction of coolant in and out flow through the module, I would think, would be important to properly monitor the module's temperature. If, in your DIY application, you are using this temperature monitoring system (or one similar), it would probably be a good idea to mimic the stock flow direction. Of course, right now I can't remember what direction that is! Someone else will know.
 

·
Registered
Joined
·
287 Posts
Yes, thermistors on most negative and most positive for S/X modules.

My only suggestion would be to keep which one you use as an inlet and as an outlet consistent. I've seen mentioned that the lower fitting is the stock inlet, but it doesn't matter ultimately as many, many conversions have paid no attention to that and done what is most convenient instead.
 

·
Registered
Joined
·
3,100 Posts
Apart from the outlet coolant temperature sensor, it's gunna get really interesting for the "doesn't matter" crowd when it comes time to change out the coolant and you have a mix of high and low connectors if the modules are laying flat or if the outlet of the battery box is from the higher module outlet.
 

·
Registered
Joined
·
926 Posts
My only suggestion would be to keep which one you use as an inlet and as an outlet consistent. I've seen mentioned that the lower fitting is the stock inlet, but it doesn't matter ultimately as many, many conversions have paid no attention to that and done what is most convenient instead.
This might be good enough for applications with light to medium discharge/recharge rates. For those of us pushing the D/R rates to their maximum, similar to what Tesla does, it probably would be wise to follow Tesla's lead. I seem to remember somebody mentioning observing a temperature difference in a (series?) electric string of cells, related to their polarity. I can't reference this info. So, someone else may have more info if this the case or not and what Tesla does.
 

·
Registered
Joined
·
170 Posts
Apart from the outlet coolant temperature sensor, it's gunna get really interesting for the "doesn't matter" crowd when it comes time to change out the coolant and you have a mix of high and low connectors if the modules are laying flat or if the outlet of the battery box is from the higher module outlet.
HAHA! Always thinking ahead. That's when you get out the big air compressor that you use for blowing out your sprinkler lines in fall... Oh wait, West Coast. Nevermind.
 

·
Registered
Joined
·
287 Posts
Don't know why anyone would string those restrictive tubes in series 🤦‍♂️

Supposed to feed off a manifold in and manifold out. Which is what Tesla does.
Yep running cooling in series will inherently result in the first module in the string being cooler than the rest, with each warming subsequently.

This is a good point that isn't discussed remy_martian, they must be cooled in parallel thru a manifold to ensure that the modules stay at the same state of health and state of charge.
 

·
Registered
Joined
·
3,100 Posts
Good

Everybody else reading this thread might not, which is why we post like we do. On this forum you happen to get help on the way to information getting thrown in for thousands to read afterwards.

Back to Nanook Lawn Sprinklers of the North - if you have a manifold, you'll clear one module with your compressed air trick and the rest will retain old coolant. It's further complicated by the intercell cooling tube having a dozen or so microchannels vs being one open tube. I don't see much choice than to use gravity and to plan for coolant changes as you design your pack.
 

·
Registered
Joined
·
926 Posts
Yes, I understand I should use a manifold system.
In no way did I mean to imply that Tesla cooled its modules in series. Of course it uses manifold systems! I thought that would be self-evident. My reference is to the cell groups, and how they are connected electrically in the modules. Can we have good discussion about this important issue without people nitpicking details about it as part of their pathetic gotcha agenda?
 

·
Registered
Joined
·
3,100 Posts
There's no "gotcha"...your posting was unclear, and you've stirred up the mud with an even more confusing posting that ends with telling everyone to leave the confusion you posted in place.

So, to hit you over the head with it, WTF are you talking about with "cell groups" and "series electrically" when this is a thermal question? Cells at the end of the thermal loop will obviously be hotter than those at the inlet. The "cell groups" are identical in size, thermally and electrically. Air cooling contributes next to nothing so the electrical plate connections are irrelevant.
 

·
Registered
Joined
·
3 Posts
I don't have any experience with the Tesla module you speak of... but plenty with cooling. As you say there are high and low connections then the general rule of thumb of high out, low in should apply.

Heated coolant will rise and therefore needs to be extracted through the high connection while being replaced by the colder coolant through the low connection.

So I would say it would matter. If you do it the other way, you're not going to be cooling efficiently and could create "hot spots" within the coolant cavity.
 

·
Registered
Joined
·
7,978 Posts
Heated coolant will rise and therefore needs to be extracted through the high connection while being replaced by the colder coolant through the low connection.
That's only true in an open tank with convective circulation within the tank - the direction of gravity is not important to cooling with coolant pumped through tubing.
 

·
Registered
Joined
·
926 Posts
My only suggestion would be to keep which one you use as an inlet and as an outlet consistent. I've seen mentioned that the lower fitting is the stock inlet, but it doesn't matter ultimately as many, many conversions have paid no attention to that and done what is most convenient instead.
So, if there is no difference in thermal management with the coolant flow direction, why would the flow direction in each module matter in a group of modules? Again, for those of us pushing the discharge/ recharge rates to their maximum, similar to what Tesla does, it probably would be wise to follow Tesla's lead.
 

·
Registered
Joined
·
3,100 Posts
If you push the discharge rate for acceleration, it's thermal mass, not coolant, that is in play.

If you push the discharge rate for extended periods, you'll cook the Tesla motor.

Cooling is for battery life, high rate charging, and extended regen (charging), primarily. Racing a car voids most warranties (I remember my dad scoffing at the one week warranty on the hemi Super Bee my brother and I were pitching him to get when shopping for his first new car).

Warming is necessary in cold climates and facilitates high rate charging...I'm not sure I've seen anyone put warming or a chiller in the battery coolant loop here.

If you get the air out of the system, it technically won't matter much which way it flows in the module. If the coolant temperature sensor is at one end only, and I don't know the details there, that had better be the outlet or you are blind to the module temperature.
 
1 - 20 of 22 Posts
Top