HV Batt Temp Sensor/Fan Logic

idk, but i've always found it lacking, and would prefer to control it myself. why not have the fan on high all the time?

 

i wonder if it is programmed that way to save energy? i can't think of another reason, and this has been going on for 20+ years and 5 generations.

 

My understanding of the logic is it runs on high for safety if there's any Hybrid Battery error codes... This will quickly evacuate any toxic fumes if that becomes an issue.

It will also run if battery temps gets too high, but is designed to run at slow speeds so you don't lose the magic of how quiet the car is when the engine is not running.

In cooler climates, there has long been a myth that you don't need battery cooling fan at all. Out here in the PNW I've met multiple people who have been told that by big battery rebuilder companies like GreenTech and GreenBean.

Of course, I bet if you asked the higher up engineers who work for those companies, they'd say that's nonsense.

In short we're in the early days of vehicle batteries and precise temperature optimization, both pre-heating and cooling are advancements that have only just begun to be addressed.

 

most bevs are liquid cooled, preconditioned when necessary and conditioned when necessary even when off and unplugged unless the battery gets too low.
we are in the early stages, but improvements are coming quickly.

 

Yeah the real electric stuff is going to have to be cooled no question about it pumps and all of it even my volt is this way I do believe and it's only going 30 mi on real electric so you get to run 300 miles and you can imagine things are going to have to be cooled seems to me it would be pretty easy to rig up a larger fan in the back of the Prius one that's a little thicker taller whatever move more CFM just because why not I could rig it to a switch up front or something and just turn it on and let it rip pretty much.

 

Kind of funny though every person or group or business that's made round cell setups for the Prius battery and I've been totally crappy so whether they're trying to use bad cells bad chemistry I don't know but everyone that Alibaba and all these companies have sold or pretty much big failures so they may get air flowing around them to cool but there are other problems apparently.

 

[QUOTE="BuckleSpring, post: 3459941, member: 205032"With the prismatics there's just no way to really cool them besides blowing air over the top[/QUOTE]

The sides are made of thermally-conductive material (except in gen 1 they were the same gray plastic as the rest) and they are dimpled so that when stacked together there is the deliberately-engineered airflow space between the modules. The cooling air ductwork runs above and below the modules; the airflow from the supply duct to the exhaust duct runs through the spaces between the modules.

 

Can you explain your findings in more depth?

As I understand it, in cooling something, most of the heat transfer occurs in the boundary layer right where the cooling medium is against the surface to be cooled.

In between sticks of cylindrical cells would seem to be a bunch of airflow that isn't the boundary layer.

 

Is it possible that the OEM design is forcing a greater volume of air over a greater surface area so that more heat is removed when compared with the non-OEM solution with a wider gap? Would it logically follow that the air temperature on exit of the battery would be higher with OEM modules when compared the the (less efficient) non-OEM setup?

 

Or, the cylindrical-cell design is the winner if your primary goal is to keep the air cool.

 

But I've always heard the round cells racked up for Prius configuration did horribly not for any specific reason they just didn't last very long or something along those effects have we come a long way since then has somebody taking some of those big Tesla type cells. And racked them up for Prius duty? And so when this happens is this an L ion tech or is it nickel metal hydride in round cylinders? I haven't seen these or looked at them online and quite some time I don't remember all the particulars just that they didn't do so well and people kind of shied away from them.

 

There's one thermistor in the air stream. In the stock pack, the others go into molded wells in the prismatic modules. I can't tell you where they go in the cylindrical retrofits.