Confused by Charging Curves/Speeds...

[N21]

Hi there! New owner trying to get my head around charging speeds and curves. I've anecdotally seen some people saying there's benefit in 'running down' the battery to a very low SoC during long trips in order to get faster charging speeds.

The way I understood it was that charging curves (like this one) were constant.

So, using this one as a theoretical example...

- If I pulled up to an ultra-rapid charger at 20% SoC, I'd get 100kW dropping off to 75kW at 40% SOC... or
- If I pulled up to an ultra-rapid charger at 40% SoC, I'd get 75kW dropping off to 50kW at 70% SOC

Have I understood that right? Or is it the case that the charging curve actually varies depending on the initial SoC. For example, arriving at an ultra-rapid charger at 5% SoC, would I get 100kW for 'longer' than I would have pulling up with 20%? Or would it be the same fixed curve in both situations?

If anyone could please ELI5, that'd be much appreciated...

Thank you.

[MotMot]

Unfortunately the rest of the charging curve does depend on the starting SOC. That’s a ‘feature’ of the id3.. And the battery temp. In summer battery temp is less of an issue… but in winter it makes a big difference.

Some cars - like the ioniq5 will start slow then as the battery warms the car charges on the curve.

[N21]

Unfortunately the rest of the charging curve does depend on the starting SOC. That’s a ‘feature’ of the id3.. And the battery temp. In summer battery temp is less of an issue… but in winter it makes a big difference.

Some cars - like the ioniq5 will start slow then as the battery warms the car charges on the curve.

Oh right, so you are better off starting with a lower SoC to reach higher sustained charging rates for longer?

[sidehaas]

Unfortunately the rest of the charging curve does depend on the starting SOC. That’s a ‘feature’ of the id3.. And the battery temp. In summer battery temp is less of an issue… but in winter it makes a big difference.

Some cars - like the ioniq5 will start slow then as the battery warms the car charges on the curve.

Oh right, so you are better off starting with a lower SoC to reach higher sustained charging rates for longer?

Yes. In fact if you pull up at 20-25% you may well not hit the rate the charge curve would lead you to believe (100kw+) at all, even in perfect temperatures.
The simple rule really with the ID3 is if you want to charge fast you need to plug in really low. In summer you might get away with plugging in at 15% and still get decent speeds. In winter you need to be below 10% if you are keen to charge fast (and have been driving for a couple of hours on the motorway to get some heat in the battery). If you do that, it works very well.
Plug in at really high SoC (30-40% plus) and it'll be really slow. You definitely won't get 75kw plugging in at 40%.

[N21]

Unfortunately the rest of the charging curve does depend on the starting SOC. That’s a ‘feature’ of the id3.. And the battery temp. In summer battery temp is less of an issue… but in winter it makes a big difference.

Some cars - like the ioniq5 will start slow then as the battery warms the car charges on the curve.

Oh right, so you are better off starting with a lower SoC to reach higher sustained charging rates for longer?

Yes. In fact if you pull up at 20-25% you may well not hit the rate the charge curve would lead you to believe (100kw+) at all, even in perfect temperatures.
The simple rule really with the ID3 is if you want to charge fast you need to plug in really low. In summer you might get away with plugging in at 15% and still get decent speeds. In winter you need to be below 10% if you are keen to charge fast (and have been driving for a couple of hours on the motorway to get some heat in the battery). If you do that, it works very well.
Plug in at really high SoC (30-40% plus) and it'll be really slow. You definitely won't get 75kw plugging in at 40%.

OK that's good to know, thank you! Will need to overcome my anxiety running to such a low SoC!

[sidehaas]

Oh right, so you are better off starting with a lower SoC to reach higher sustained charging rates for longer?

Yes. In fact if you pull up at 20-25% you may well not hit the rate the charge curve would lead you to believe (100kw+) at all, even in perfect temperatures.
The simple rule really with the ID3 is if you want to charge fast you need to plug in really low. In summer you might get away with plugging in at 15% and still get decent speeds. In winter you need to be below 10% if you are keen to charge fast (and have been driving for a couple of hours on the motorway to get some heat in the battery). If you do that, it works very well.
Plug in at really high SoC (30-40% plus) and it'll be really slow. You definitely won't get 75kw plugging in at 40%.

OK that's good to know, thank you! Will need to overcome my anxiety running to such a low SoC!

If the car is new to you, it'll just take a bit of time to learn roughly what mi/kWh you get in different conditions, but just as importantly, how much you can vary it if you want to by changing your speed. I tend to set ACC to 70, if I'm running worryingly low a stretch at 65 makes a big difference, equally if I've got more than I need as I'm getting close to the charger, upping to an indicated 72-73 also makes a surprising difference sometimes. Of course I wouldn't ever drive faster than that Once you know the car it becomes fairly straightforward to arrive with a fairly low SoC as long as there is a good, reliable charging site in approximately the right place.

[Mark55]

Hi
Charging speeds just vary. A lot. The battery state of charge and the battery temperature being the main two variables. Followed by the all powerful battery management system that does the actual controlling.

At 8% soc I have seen on a 250 kw or 350 kw charger a speed of 100 kw. the battery was at 23c. The car has this info but does not present it to you. For that you need an app called Car Scanner ELM OBD2 and an OBD2 dongle.
Tronity app records a charging curve whenever you charge.

Pod point 50 kw charger, the battery was cold and needed around 20 minutes of charging to heat it up to enable around 32 kw

For example a home charge controlled by an Ohme Pro charger and Octopus Intelligent, I have noted that in the past the the overnight charge would be at 7.5 kw and end not that long after midnight. But now the charge as you can see goes on all night. with very differing power levels.