Impressive 97kW peak charging rate at MFG Purfleet

[LittlePluggers]

We did a long trip yesterday in our MG ZS LR and managed to stop at the newly opened MFG Purfleet to try one of the eight 150kW chargers.

We arrived around 10pm with 11% with a nice warm battery from a 50mile journey to reach it, ambient temp was 10c.

When it started charging it was up at 88kW, we couldn't believe it so we looked on the charging screen which at that point was recording 243amps at 357volts (86.75kW).

Peak charging rate was 97kW (at 38%) and the average was 88kW over the session.
We charged from 11% to 41% in just 15mins with 22kWh consumed.
Before anyone asks, the battery heater was off.

Very impressed, if we had used at 50kW charge it would have taken 25-30 minutes.
I'm also curious about the voltage provided by the charger it was expecting it to be ~400v.

 

[drmcw]

Fantastic! The battery is around 400V when fully charged so you'd only ever see that at the end. See here.

 

[LittlePluggers]

Fantastic! The battery is around 400V when fully charged so you'd only ever see that at the end. See here.

ah that makes sense, current voltage != voltage being provided by the charger.

 

[Coulomb]

current voltage != voltage being provided by the charger.

Actually the present voltage provided by the charger will be quite close to the present battery voltage. It has to be, because power equals I²R, so even one ohm of resistance in the cables at 250 amps equals 250² = 62,500W of losses, which would cremate the cables in short order. In reality, the resistance would be kept to about 10 milli-ohms, so the losses are a more manageable 63W. My guess is that charger could go to 300A, so nearly 100W of losses. Hence the water cooling for the cable.

So the voltage drop across the cables equals I•R equals 250•0.01 = 2.5V. So if your battery was at 370V, then the charger would be putting out roughly 372.5V to maintain 250A.

Of course, a 150kW charger is probably rated at about 600V, that is, it can probably provide up to 600V at 250A, and perhaps 500V at 300A. It's even possible that the maximum current is 250A (so 150kW is only possible with a 600V battery), in which case your 97kW (at 388V) would have "maxed out" the charger! It could be that the car could have taken a little more power than the charger could provide. That's the hassle of a low battery voltage: you can run out of current limit way before you run out of power limit.

Thanks for the report. I wish we had charging facilities like that in Australia.

 

[drmcw]

Of course, a 150kW charger is probably rated at about 600V, that is, it can probably provide up to 600V at 250A, and perhaps 500V at 300A. It's even possible that the maximum current is 250A (so 150kW is only possible with a 600V battery), in which case your 97kW (at 388V) would have "maxed out" the charger! It could be that the car could have taken a little more power than the charger could provide. That's the hassle of a low battery voltage: you can run out of current limit way before you run out of power limit.

Yeah, I remember reading about the 350 kW chargers can only deliver 350 kW to a 1000 V battery, so the current limit is the more important figure when it comes to rapid chargers for the majority with 400 V packs.

 

[drmcw]

ah that makes sense, current voltage != voltage being provided by the charger

No should be the charger voltage. Best to think of the charger as a current pump; Coulomb explained it in his post.

 

[Merry]

You did better than I did at the mfg site in Standish, only got 40kw on their 150kw chargers. Looking at the reviews on plugshare it seems pretty common for that site.

 

[AreFriendsElectric]

That site is just down the road from me. Useful to know for back up in a years time when my EV finally arrives…