alt Hacker News> batteries next to these chargers that they charge "off peak"
I don't think that's what they'll do. Charging off peak means being able to store the entirety of the energy demand for the power station in a battery, which is going to be very expensive (assuming 20 cars charge during peak hours every day, that'd mean having to swallow the cost of 20 cars worth of battery per charging station. Good luck getting a good ROI with that).
Instead I think they'll just use the battery so that they never drain the full power of a charge when a car is charging. Drawing a megawatt of current 5% of the time is putting lots of pressure on the local grid, and it can be mitigated by having a battery with the capacity of a car battery that you charge slowly during the whole day (including during peak hour) and discharge fast when a car is charging (for instance, if in average you have 2 cars charging for 5 minutes every hour, you can draw 166kW continuously instead of having bursts of 1MW consumption).
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So do those batteries support fast charging AND fast discharging?
> if in average you have 2 cars charging for 5 minutes every hour, you can draw 166kW continuously instead of having bursts of 1MW consumption)
You definitely need to have that to not load the grid with 1MW, but the question still remains what the capacity of the battery is. A charger that promises a 5 minute 1MW charge BUT which can only do it once per hour and then falls back to 200kW doesn't seem as special as a charger that actually charges a car every five minutes.
It's convenient to get going in 5 minutes. But the time you REALLY want the charger to be quick is when you are third in line to charge at that charger.