weight is always a penalty - in fact, somewhat hypocritically, Elon claims that the structural monolithic packs are to save weight. hypocritical is because he is adding hundreds of pounds of unnecessary weight to 'save' weight. yes EVs are more efficient with onboard energy, and yes regen helps a bit (not as much as you'd think due to roundtrip energy losses), but more weight will always take more energy to accelerate, decelerate and change direction. even rolling resistance of tires is higher with greater weight. and you are correct that with current way of doing things, smaller battery is limited in its capacity to deliver energy - typically to 3C sustained and 5C max. in large part this is due to the fusible links necessary to interconnect cells in parallel - that is the only defense against uncontrolled current from adjacent cells if one were to short out. to fuse, the link has to get hot enough to melt. so you're running all interconnects hot, especially when battery is near max output, because otherwise they wouldn't work as fuses. energy loss in interconnect is typically higher than internal energy loss in cells. by only having series connections and having relays on each module we eliminate the need to fusible links and therefore can use very low impedance interconnects. regular production 2170 cells, such as those from molycell that anyone can buy at retail, are capable of 15C max discharge. we're proven it on the dyno with our D2EV, drawing 1,000W (1,350hp) on the dyno continuously for 45 sec with minimal heat rise. the other aspect is cooling, which our architecture optimizes far better than conventional approaches. a 3KWh modbatt module built with molicell cells can deliver 30KW continuous and 45KW peak. not for long due to capacity, granted, but a 15KWh pack made of 5 modules, can deliver 150KW continuous and 225KW peak. plenty for a compact car. the intent is to have your car configured for your typical daily use, like commuting. if you need more battery for a long trip, you go to a service station and lease more modules. they install them for you jiffy lube style. return when done. you can also have modules in your home, but they wouldn't be sitting idly in the garage - they would be in your powerwall, providing backup power, storing your solar system output, etc. GM 'modularity' is in 50KWh increments which are way too big to handle manually. also they have parallel connections inside the packs, requiring fusible links and all the inefficiency that goes with those. plus, fusible links don't always prevent fires (and can actually contribute to them) - just ask GM about bolt batteries 😉 hope this answers the questions, but if not i would be happy to explain further.
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