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What Makes The Tesla Model 3 Battery Pack So Light?

George Bower

By: George Bower

May 29, 2018 at 5:39am ET

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It’s not just the new 2170 cells.

Major changes to the battery pack structure have been made as well.

The Tesla Model 3 pack weight (lb/kWh) is 15% lighter than the original Model S 85 kWh battery and

6% lighter than Tesla’s most advanced battery in the P100D.*

Of course, the new 2170 cells are a big part of the weight savings. Musk divulged that Tesla has quietly increased the nickel content of their cells which should decrease the weight of the pack.

See: Tesla Panasonic Quietly Outmaneuver All Lithium Battery Manufacturers

Also, the new 2170’s result in a smaller pack footprint because the cells are taller and this lowers the pack footprint and therefore the weight of the pack case. According to Jason Hughes, the Model S battery case is a whopping 275 lbs, which is over 20% of the pack weight so reducing the protective case weight is a big deal.

model 3 1

Major changes have been made to the Model 3 pack structure. These changes were revealed in an EVTV video we shared here on Inside Evs.

See: Watch As Tesla Model 3 Battery Is Removed And Disassembled

In this video, Jack Rickard spent over an hour disassembling the Model 3 pack. Lots of interesting things about the pack were discussed: some fairly common knowledge and some not.

Tesla has now consolidated all the power electronics into the pack itself. The AC charger and the DC-DC converter are now integral with the pack. In model S, these units were scattered about the car. Total wiring length has been drastically reduced, and here’s another interesting tidbit: Tesla has combined both the AC charger AND the DC-DC converter into one smaller and lighter unit (39:25 into the video).

All well and good but the structural changes were a bit more subtle and were not revealed until Jack removed the battery pack lid.

Photo courtesy EVTV

You can see in the screenshot that the lid is flexible and would offer little crash protection for the pack. Now the surprise. There are no sides on the battery pack. Other than the flimsy pack cover, the battery modules are completely exposed. That is totally opposite the Model S and Model X pack. In Model S, the battery case is thick and heavy to protect the cells and to provide rigidity to the car. The case in model S is solid metal ¼” thick.

model 3 3

The lack of sides is shown again in the screenshot below.

model 3 4

Also, notice the multiple attachment points of the modules to the case bottom. The modules themselves are adding rigidity to the pack as well.

What do we conclude from the fact that there are no sides to the pack? Has Tesla moved crash protection from the battery case to the body structure?

Consider the following figures from Tesla’s emergency response guide.

In the Model S, the heavy battery case provides the crash protection for the battery with minimal high strength steel.

Photo courtesy Tesla emergency response guide

Now check out Model 3. Lots of high strength steel around the pack.

model 3 6

Has Tesla transferred case structure weight and battery protection from the battery case (Model S) to the body? This makes total sense because Tesla has to transport completed battery packs from the Gigafactory in Nevada to the assembly plant in Fremont. There’s less weight to haul.

Makes sense to us.

What do you think?

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Comments

What do you think? Maybe the flammability issues with Tesla’s battery have been dealt with in another way? Perhaps the intumescent goo been resurrected? Let us know in the comment section.

*P100D and Model S85 pack weights adjusted upwards to include AC charger and DC-DC converter since M3 pack weight includes those items.

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