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Discussion Starter #1
Hello,

If you dont know already I am working on a range extended trailer. I am currently using a battery pack from a Tesla Rav4 EV but as soon as I find a P100 kwh pack I am buying it and using that instead. (please let me know if you find one at a reasonable price)

The Rav pack has a dehumidifier. It actually says "dehumidifier" on the part sticker. I need this battery to be weather tight and I need to know more about these valves. I have a hard time believing that they would build anything that would allow water to get into the pack but I need to make sure.

I just uploaded this video so you can see what I am talking about.
https://youtu.be/hIuwL95NntQ

If you have any experience with these please let me know.

Thanks!
 

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I have a hard time believing that they would build anything that would allow water to get into the pack but I need to make sure.
Thanks!
I have no direct experience with those Tesla packs, but..
1)....I find it hard to believe the pack can be 100% sealed airtight.
2)....The pack will undergo significant temperature changes , both from cell warming, and external ambient conditions
3).... As a result of the above, the pack will" breath" air which will inevitably have a % of water vapour with it.
Hence , it makes sense that they have fitted a system to "manage" that in/out airflow and provide some form of de-humidification. ?
Just a SWAG !
 

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Discussion Starter #4
Thanks for your input. I thought of a test I can run.
Take the cover off place something underneath, run water over top, see if it comes through the dehumidifier.
 

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Maybe they are maintaining a positive air pressure in the pack? Would be useful to apply 12V to that pump and see what happens? Is the external air sucked in through the dehumidifier beads?

The Model S/X packs are not strictly 'airtight' because they have the exhaust valves along both sides. They also don't have any dehumidifier beads. The only feature they do have is a pressure equalisation valve.
 

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Discussion Starter #6
Maybe they are maintaining a positive air pressure in the pack? Would be useful to apply 12V to that pump and see what happens? Is the external air sucked in through the dehumidifier beads?

The Model S/X packs are not strictly 'airtight' because they have the exhaust valves along both sides. They also don't have any dehumidifier beads. The only feature they do have is a pressure equalisation valve.
Good idea. I should be able to easily send 12 v to the pump to see what happens. I imagine that it would blow air out but Ill see.
 

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Smart uses a small desiccant cartridge on their battery pack. I haven't looked into the details, but I assume they're expecting a small amount of water vapor to enter either though a pressure equalization valve or because the cooling system isn't 100% vapor tight.
 

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Discussion Starter #8
I tested the cover. The larger round one is a one way check valve that lets air out but not in. In heavy rain though I am not convinced that rain wont get in so I need to make some kind of cover for when it rains. The other one on top I am not sure about. It looks like a manual bleed valve. I havent taken that one out yet.
 
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