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HEPA Filter: Using Bioweapon mode vs Not

Hi!

There has been a lot of data and reports showing the great power of the Model Y's HEPA filter when using Bioweapon mode but not a ton of talk about how effective the HEPA filter is when not using it. When are you supposed to actually use Bioweapon mode?

If there was a car on fire next to me with thick smoke coming my way I would for sure turn it on, but what about just casual driving on a smoggy LA day? Or in stop and go traffic where there is a lot of exhaust and brake dust?

Are you supposed to use it all the time or just in extreme emergencies?

If not using it, how much filtration are you still getting just by it having the HEPA filter installed?

Thanks!
 
Hi!

There has been a lot of data and reports showing the great power of the Model Y's HEPA filter when using Bioweapon mode but not a ton of talk about how effective the HEPA filter is when not using it. When are you supposed to actually use Bioweapon mode?

If there was a car on fire next to me with thick smoke coming my way I would for sure turn it on, but what about just casual driving on a smoggy LA day? Or in stop and go traffic where there is a lot of exhaust and brake dust?

Are you supposed to use it all the time or just in extreme emergencies?

If not using it, how much filtration are you still getting just by it having the HEPA filter installed?

Thanks!
I was actually thinking about this the other day when I read an article about how effective the filters are against pollen. The grass pollen right now is ridiculous.
 
the normal filter is a merv 8 filter, similar to a house, it will block pollen out of your car just like a normal filter in most cars. The bioweapon filter increases that to a believe a merv 16 or 20 which is why it can filter out all of those super tiny particles. Merv 20 is what hospitals use. but the normal filter in the Y will block out pollen and dust just like normal car filter. The extra biodefense will most likely use a little more electric power as its hard to push air through it to get it filtered, same as in a house. Most house systems cant handle a merv 13 as it puts a lot more pressure on the air system to push it through. I would guess biodefense will lesson your range a tiny bit and i bet it could be tested.
 

SageBrush

REJECT Fascism
May 7, 2015
13,729
18,932
New Mexico
BDM is a Tesla marketing term that combines positive air pressure inside the cabin with HEPA filtration of all outside air. The user manual says

If your Model Y is equipped with the medical-grade HEPA (High Efficiency Particulate Air) filter, this filter ensures the best quality air inside the cabin whenever the climate control system is on and outside air is entering the cabin (recirculate is off). The HEPA filter is extremely effective at removing particles, including pollution, allergens, bacteria, pollen, mold spores, and viruses. Both the HEPA filter and the secondary filtration system also contain activated carbon to remove a broad spectrum of odors and gases. When you engage Bioweapon Defense Mode, the positive pressure inside the cabin minimizes the amount of outside air that can enter the vehicle.

The last sentence is misleading. They meant that non-filtered air from outside is minimized. Outside air is actually increased markedly to achieve positive pressure in the cabin
 
I also find this part confusing:

If your Model Y is equipped with the medical-grade HEPA (High Efficiency Particulate Air) filter, this filter ensures the best quality air inside the cabin whenever the climate control system is on and outside air is entering the cabin (recirculate is off)

At least in my area, when I use the Auto mode it is always recirculating. Is this saying I'd actually get better quality air if I override that? I assumed even on recirculate that it is using HEPA filter to clean the recirculating air but I guess I'm not sure.
 

SageBrush

REJECT Fascism
May 7, 2015
13,729
18,932
New Mexico
I also find this part confusing:



At least in my area, when I use the Auto mode it is always recirculating. Is this saying I'd actually get better quality air if I override that? I assumed even on recirculate that it is using HEPA filter to clean the recirculating air but I guess I'm not sure.

Best air quality is not just absence of particulates. It is also low CO2 and comfortable humidity. Ventilation (aka air exchange) is needed to keep the cabin CO2 from rising; and depending on the environment outside air may have a more optimal humidity. Partial recirc is for the most part an energy conserving approach to handling conditioned air.

Auto mode is fine unless the air entering the cabin stinks.
 
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SageBrush

REJECT Fascism
May 7, 2015
13,729
18,932
New Mexico
So far as I can tell from google searching, recirculated air is not passed through the HEPA filter. That sounds like a potential problem for CO2 build-up in the cabin and entry of e.g. particulates into the cabin of outside air via air gaps but I don't think it is in practice because recirc in AUTO mode is far from 100%

Running BDM has serious trade-offs: For one it is noisy; and second, if the air coming in at high flow rate is too hot/cold for comfort the conditioning is going to be a big power drain. It is akin to running A/C in your home with the windows open on a hot and windy day. Smart usage of the A/C unit is AUTO in general and a brief use of BDM if needed when passing through a particularly stinky or smoky area, either because the cabin air has become polluted or you want to avoid any air entering the cabin through the cabin envelope other than through the HEPA filter.

This business of interior air quality has been dealt with in depth by the PassivHaus (PH) building community because they go to great lengths to make the home envelope very tight (below 0.6 ACH at 50 pascal.) Their solution is to also have energy conserving ventilation, but the relevant point for us is how much ventilation they recommend. Depending who you ask, answers vary from 0.35 - 1 ACH. If the air cabin volume in a car is 120 feet cubed then the fan is operating at 0.7 - 2 CFM
 
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ATPMSD

Active Member
Mar 12, 2021
1,748
1,696
Atlanta, GA
I have looked everywhere to purchase the BWD filters and even Tesla.com does not sell them. Where can you purchase these BWD filters?

Call an SC and ask for the parts department, I believe it is part # 1495167-00-B

Here is the online parts catalog: Parts Catalog

And here is where you can subscribe to the Service Manual for free: Tesla Service
 

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