3 ms·

Would it not be significantly easier if we're using 4 or 5 independent modules instead of a giant monolith? Aren't cars routinely lifted into the air when being

by cjdell 4y ago

Would it not be significantly easier if we're using 4 or 5 independent modules instead of a giant monolith? Aren't cars routinely lifted into the air when being serviced? I understand that the structure of the car's body may be suboptimal and require extra reinforcement but if we're really serious about EV adoption and reducing battery cost then perhaps a trade-off worth making?

NickNameNick 4y ago
If you want the batteries to be removable, I suspect the extra couplings in the water coolant loop would make that problematic.
- silversmith 4y ago
  Check out how tractor hydraulic attachments handle liquid couplings. And hydraulic systems work at much higher pressure than simple coolant loops.
chiph 4y ago
For an EV the main design constraints are aerodynamics and weight. If you need to add additional reinforcement to make up for the battery packs that haven't been installed, you're carrying that weight around all the time and taking a range penalty. So assume your vehicle has 3 packs. You normally run it with just one pack because that's all you need to commute and run errands during the week. When you go visit the relatives in Florida, you install the other two packs to get the additional range. The car needs additional structural elements to meet safety standards when the extra packs aren't installed and they add 5% additional weight. That's weight you're carrying around every day, and that has a range cost. Could it be worth it to swap out the extra structure elements when you install the extra packs, so at least you aren't taking the range penalty while driving long distance? Yes, but the manufacturer isn't going to want the liability of a customer removing what is a passive safety device, and then forgetting to reinstall it when they go back to city travel using only one pack. NHTSA will also have input to this. From what I can tell - the applicable FMVSS is this one that deals with EV side impact protection, electrolyte spills, and electric shock. https://www.nhtsa.gov/document/final-rule-occupant-protection-interior-impact-side-impact-protection-fuel-system https://www.nhtsa.gov/document/final-rule-occupant-protectio...

by cjdell 4y ago

NickNameNick 4y ago

If you want the batteries to be removable, I suspect the extra couplings in the water coolant loop would make that problematic.

silversmith 4y ago
Check out how tractor hydraulic attachments handle liquid couplings. And hydraulic systems work at much higher pressure than simple coolant loops.

chiph 4y ago

For an EV the main design constraints are aerodynamics and weight. If you need to add additional reinforcement to make up for the battery packs that haven't been installed, you're carrying that weight around all the time and taking a range penalty. So assume your vehicle has 3 packs. You normally run it with just one pack because that's all you need to commute and run errands during the week. When you go visit the relatives in Florida, you install the other two packs to get the additional range. The car needs additional structural elements to meet safety standards when the extra packs aren't installed and they add 5% additional weight. That's weight you're carrying around every day, and that has a range cost. Could it be worth it to swap out the extra structure elements when you install the extra packs, so at least you aren't taking the range penalty while driving long distance? Yes, but the manufacturer isn't going to want the liability of a customer removing what is a passive safety device, and then forgetting to reinstall it when they go back to city travel using only one pack. NHTSA will also have input to this. From what I can tell - the applicable FMVSS is this one that deals with EV side impact protection, electrolyte spills, and electric shock. https://www.nhtsa.gov/document/final-rule-occupant-protection-interior-impact-side-impact-protection-fuel-system https://www.nhtsa.gov/document/final-rule-occupant-protectio...