Tesla S Module Mounting Orientation - Your Experience?

2661 Views 6 Replies 4 Participants Last post by remy_martian, Jan 8, 2022

Jb24601

Discussion Starter · Jan 7, 2022

In the Tesla S cars, the battery modules are mounted in a flat position (cells oriented vertically).
But us DIYers often mount them sideways, with the cells horizontal.
Has anyone using these batteries this way had any problems?
Are they that well built that they can take the pounding a vehicle can dish out, while laying sideways?
I don't see any structural support for that position, and fifty pounds of batteries laying on top one another with a (very) thin cooling tube separating them just sounds suspect.
I've not seen nor heard of any problems, and there may be none, but it wasn't designed that way.
Thank you for sharing your experience.

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remy_martian

· #2 · Jan 7, 2022

You are correct. No structural support and there's a risk of crushing the ribbon cooling channels, which are aluminum.

Lots of people do it, hard mounted. I wouldn't because of the channels. The cells are in a steel jacket, so no worries there for me other than they make for a nice hammer on that aluminum ribbon.

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reiderM

· #3 · Jan 8, 2022

The modules are very solid, and every cell is supported and held firmly in place by a clear plastic membrane on the top and bottom. If such a membrane wasn't there, the cells would be able to just roll about freely within the module! There is not a risk of crushing the coolant channels. Primarily because of this membrane, but also because the cells are not that heavy and the coolant channels are not that weak.

How do I know that the cells will do fine when placed vertically? Well, just about every tesla module that has ever been sold has come out of a crashed tesla. When a car crashes, it experiences rapid momentary deceleration of often well over 50 g's. That deceleration is all directed in the horizontal, which would be the same direction as having the modules mounted vertically for normal driving. You also will never see 50 g's of acceleration in normal driving. So you say it wasn't designed that way, but in a sense, it was.

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Jb24601

Discussion Starter · #4 · Jan 8, 2022

Further thinking reminded me of the fuse wires (the little wires soldered to the top and bottom of each cell).
If the batteries in the pack "settled", would they not separate from the fuse wires? They might flex a bit but some would break. The attachment point is a form of bus bar.
So if no one reports cell issues which the broken wires would cause, then might we conclude these modules are able to mounted sideways? Long Term?

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57Chevy

· #5 · Jan 8, 2022

Harsh vibration would be far more stressful than orientation. The manual is very enthusiastic about not using an impact wrench on the bolts, I believe they had some failures due to this

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remy_martian

· #6 · Jan 8, 2022

reiderM said:
The modules are very solid, and every cell is supported and held firmly in place by a clear plastic membrane on the top and bottom. If such a membrane wasn't there, the cells would be able to just roll about freely within the module! There is not a risk of crushing the coolant channels. Primarily because of this membrane, but also because the cells are not that heavy and the coolant channels are not that weak.

How do I know that the cells will do fine when placed vertically? Well, just about every tesla module that has ever been sold has come out of a crashed tesla. When a car crashes, it experiences rapid momentary deceleration of often well over 50 g's. That deceleration is all directed in the horizontal, which would be the same direction as having the modules mounted vertically for normal driving.

Funny you should mention that. I have one of those 60g (guessing) impact cars.

Inside the battery case, each module sits on a rectangular cross section rail and is screwed down to it. On the thin piece of garolite on each side of the module that you vertical aficionados slide into slots. That thin piece of garolite has some compliance in the vertical.

Several of the modules in that car's battery case shattered the garolite (energy absorption) in shear, but modules survived that loadpath. The modules themselves are not in contact with those rail walls that form module compartments (fire containment is another function). They are suspended on the garolite which produces a known high magnitude loadpath in shear and some vertical shock isolation.

Now...I don't know what the loadpath is beyond the garolite mounting wings, but I do know that a 60g crash (or impact from a hard mounted battery case) for a 50 pound module can exert a ton and a half of force in a loadpath that is transmitted through the full thickness of the pack if you don't use the garolite ears. The aluminum cooling channels are the jelly in that PB&J module sandwich.

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remy_martian

· #7 · Jan 8, 2022

I think the concern about an impact wrench is if the impact selector is in "righty-tighty"...that would strip the aluminum threads, totaling the car.

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