BioSehnsucht
Model 3 LR
The way V3 is designed, "paired" stalls don't share, though on a large enough scale all stalls share (in theory you could hit limiting by having many/all stalls start charging from low state of charge at the same time, as there is some limit to how much power can enter the site), so there is no need for stalls to have some kind of extra power source to maintain charge rate when sharing vs a neighbor.It is a long shot, but I did put some thought into it...
Say be have a bank of Powerpacks - peak power output = P1
if we have N cars charging at anytime the average power each cars gets is P1/N.
So the question is if we size the Powerpacks for peak energy storage or peak charging..?.
If we have an auxiliary battery in each stall which can output P2..... (assuming it is fully charged, or charged enough)
The peak rate of charging may be P1/N + P2, or perhaps just P2 where P2 is > P1/N.
We know Maxwell cells can absorb power and discharge power at a higher rate than a normal battery....
In reality it is most unlikely to be true, the investor day may simply have been moved to promote solar..
Utility power comes in, gets turned into a big 400V DC power bus, and then each stall has a single DC-DC stage (vs lots of smaller AC-DC ones on v1/v2 superchargers) that uses that 400V as an input and outputs whatever DC voltage and amperage is needed by the car. If you want to give the system a battery buffer, it is better to have it sit on the shared 400V DC bus, so that you never have a situation where capacity goes unused when it could be used (you might have it go unused if it just isn't needed, but never because half the stalls are empty so half the batteries aren't usable). Plus, this way you can use the big battery for demand charge reduction and possibly even grid energy services (if they wanted to get real fancy with a real big battery). Each DC-DC stage (one per stall) can provide maximum power the car can take, so adding a battery to the stall doesn't help. Plus the DC-DC stage is in a centralized equipment area, not the stall, so having a battery there for extra oomph is going to be complicated...