“Good point, and it prompts this thought. What if recharging stations had big electricity storage on-site. Like big underground batteries or something. They would recharge them overnight when there’s low demand for electricity. Then they would use the stored power to charge people’s cars during the day. No doubt already been thought of and shot down but figured I’d say it out loud FWIW...”
Tesla already does this with their Megapacks each 20 foot sized container holds 5 megawatt hours. You can pull down that pack at 5C if you chose to. That’s 25 MW that’s 50 super charger stalls at 500kw each running flat. From a single 28 ft shipping container sized module that’s only slightly larger than the supercharger hardware itself. At ten foot wide parking spaces two megapack sit behind 4 stalls then and would power them at their full rate for 5 hours. That’s not how SC work if you are at 20% they give full rates and as your cross above 60% it’s slows down and by 80% ypu should stop but if you keep going it’s under 100kw by that point.
So the real metric is how many 75
KWh model 3 can a megapack fill. At 8% DC to DC charging losses which is typical for SC not L2 rates. You need 81kWh for a 75kWh usable pack that’s 122 full charges per shipping container pack. More because you actually do 20/80% in that case it’s 204 x 20/80% charges.
CATL is kicking butts and taking names
[As of May 2025, CATL offers a 20-foot containerized energy storage system (ESS) called TENER that holds a capacity of 6.25 MWh. The company later announced an even higher-capacity solution called TENER Stack, which achieves 9 MWh in the footprint of a 20-foot unit by stacking two containers. ]
Two 20 footers fit behind four SC stalls then and at 9MWh or 9000 kWh for a 48kWh 20/80% charge of a model 3 that’s 375 super charges per day off those four stalls at any rate those stalls can put out the grid won’t see any of the peak loads.
So how much load is an 8 hour overnight off peak charge for those two packs...allowing for 5% AC\DC BMS loss over 8 hours to put in 18 net megawatt hours you need 2.36MW from the triple phase 7.2-12kv grid and a 2500KVA 3p transformer to do so. Not that large 2.5m x 2.4m x 2.6m.
[2500 kVA transformer can be approximately 79 inches (W) x 120 inches (L) x 89 inches (H) or 2500 mm (W) x 2400 mm (L) x 2630 mm (H) ]
2,362,000(watts)÷12,000(volts)=196.83amps single phase.
Triple phase is 2.77 times less than 1p amps
196.83/2.77= 71.06 amps in delta wired triple phase @12kv
Yeah you are not “taking down” the local grid with a 72 amp draw.
Typical 12,000 volt triple phase power pole distribution line size is 636 kcmil....The average ampacity for a 636 kcmil bare Aluminum Conductor Steel Reinforced (ACSR) line is typically in the range of 750 to 800 amps.
Again it’s FUD nothing but FUD that a load of that size would even dent local grid capacity. I look at my Wal-Mart lines all the time there is two sets of 3 phases running last it with at least 636 size lines of not larger they are thumb sized or bigger. There actually is 7 conductors on those poles one up top then two triple sets running under them. One triple set is tapped and it goes into the Wal-Mart and keeps going past it to the home Depot and Sam’s Club right next to it the other triple set also keeps going. Those poles are carrying at least 700 amps times 6 as each conductor can carry 700 amps loaded down. These are regular wooden poles 30 feet up on a typical two lane road.
Those ordinary neighborhood sized poles are capable of carrying 50 megawatts of single phase loads Y wired or 61.5 delta wired triple phase loads. Again FUD pure and simple.
Okay, got it. Thanks for laying all that out. Sounds like it’s feasible and in fact is already being done by Tesla.