Ownership Verified: Fuel? Where we’re going, we won’t need fuel! ==>NooDle’s eGolf

blackman

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Especially AC charging at low amperage apparently has up to 15% losses


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leviathan

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Well, it does make sense. At any power the battery and charging controllers and a whole bunch of electronics have to run, and they take up a constant amount of power - around 200-300W is normal in a Tesla, I assume the VW is similar. If you're charging at a decent speed (11kW AC), it's a rounding error. If you're charging single-phase at 16A (3.7 kW), it's already using up 5-10% of the power flowing into the car. If you slow down the single-phase charge, the percentage becomes even higher - 15% at an 8A single-phase charge may be realistic.
 

NooDle

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Thanks! Hadn’t thought of that, especially since I thought this was more noticable at higher amperages/temperatures/charging speeds.

I’ve only got a single phase 16a at home so I guess it’s something I’m stuck with. I still don’t quite understand how 3 phase charging yields a lower charging loss? 3 times the power = 3 times the loss, no?
 

93Flareside

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Thanks! Hadn’t thought of that, especially since I thought this was more noticable at higher amperages/temperatures/charging speeds.

I’ve only got a single phase 16a at home so I guess it’s something I’m stuck with. I still don’t quite understand how 3 phase charging yields a lower charging loss? 3 times the power = 3 times the loss, no?
no, but let’s wait for @narf to tell us why.
 

narf

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Thanks! Hadn’t thought of that, especially since I thought this was more noticable at higher amperages/temperatures/charging speeds.

I’ve only got a single phase 16a at home so I guess it’s something I’m stuck with. I still don’t quite understand how 3 phase charging yields a lower charging loss? 3 times the power = 3 times the loss, no?
Well. It depends. There are two competing charging losses to look at.

First, there is "operating the car". I'm guessing it has two standby modes, "properly off" likely uses some low amount of power, "off but charging" definitely uses more because it has to power more computers, power the high voltage electronics, etc.
You could say the difference between those two modes is your first charging loss, and this increases with the amount of time you spend charging, so it increases with slower charging speed.

Second, there is "actual charging loss", ie the ratio of "energy entering the charging electronics" and "energy actually stored in the battery".
This should be higher with AC compared to DC because the car has to convert it to DC, while the to-DC-conversion in a DC charger likely isn't counted towards your charged amount.
This probably should also be higher with higher charging speeds, but that's just gut feeling. Battery chemistry and charging electronics might each have an optimum charging speed for efficiency that might be somewhere in the middle, or near the bottom, or (less likely) near the top.

Now, which is worse? It depends, I guess.
Very slow charging, ie single phase 3.x kW, is very likely going to be impacted by the "operating the car" issue.
Wether very fast charging introduces other losses that outweigh the saved higher "operating the car" losses, who knows.


One thing you could test to at least partially optimize this: How much power does your car draw if you have it plugged in at home, but it's not charging? e.g. it's set to charge to 80% and has reached 80%, how much is it drawing to maintain that SoC and the electronics around it?
Then compare that to how much % it loses if you keep it unplugged and undriven, assuming you have long enough periods of non-use to get a significant percentage drop that's not just 1% or so because of rounding errors and such.

If the car is dumb about this then "8h with single phase AC" might be more efficient than "8h plugged in with triple phase AC where only 2h are actually charging, but faster, and the other 6h are still operating all the wasteful electronics".
If the car is smart and powers itself way down then triple phase will likely be more efficient.
 

NooDle

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Interesting! Thanks for that!. Afaik the car uses 100/200w standing still with the aircon off so that makes sense.

Another weird thing :

5f5bd6a2395b4616dc265cd014ee7fd5.jpg


Does it throttle so much in the last couple of %? It said 2hrs at 94% and a couple of minutes later it still says 1 hr.

4% = roughly 1,2 kwh, or about 20 minutes at 3,7kw...

Edit : Now it says 30 minutes at 97%...go home drunk, you’re car

Edit2 : it actually took 20 minutes as it should have. WTF?
 
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NooDle

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Me inside, car off. Display still tells me actual consumption (in kwh/h which is funny)
 

narf

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So probably some medium-standby state with some stuff running. I'd expect the locked-and-off-for-a-while state to use much less, ie no high voltage system at all. Key question would be if it can reach that off-off state while plugged in. If not then it'd make sense to unplug at home if full and staying home for longer. If this saves, say, 100W of car standby, that's 16.8kWh over a week of lockdown at home.
 

eizbaer

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So probably some medium-standby state with some stuff running. I'd expect the locked-and-off-for-a-while state to use much less, ie no high voltage system at all. Key question would be if it can reach that off-off state while plugged in. If not then it'd make sense to unplug at home if full and staying home for longer. If this saves, say, 100W of car standby, that's 16.8kWh over a week of lockdown at home.

If the car is plugged in but the charge is considered finished, the monitoring systems will shut off and those 100-200W should drop considerably after some time, typically 15-30 minutes.

This is from the experience we made while working on a load management system and which led to certain issues for us. Because it means you can’t reliably pause the charge completely (only limit the amps down to a minimum of 6A) for extended periods of time! The car will „fall asleep“ and once the charge is resumed (I.e. the charger allowing a current draw) not realize what’s happening because it’s not monitoring for it. There are workarounds (if there’s not enough power just send 6A to every charger in turn every few minutes - pretty idiotic, but it „works) and nowadays more cars actually support a wake up function, but about 4 years ago that was the state of things.

TLDR: AC charging communication between charger and car is super limited and dumb...
 

NooDle

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Doing a largeish roadtrip/test of charge points across .be. Because I can.

Results so far :

- I can charge pretty much everywhere I want, have not yet found a charger that doesn’t work. Tried across different networks/providers (Allego, Total, FastNed, Ionity)

- Average speed 91 km/hr. Average consumption 16,7kwh/100 kms which is pretty awesome considering I’ve spent most of the time on the highway and I’ve gone as high as I can go in Belgium (694 m altitude)

- EVs are getting more and more visible. Spotted charging next to me : Fiat e500, VW eUp, Opel Corsa e, Porsche Taycan (twice!), Kia eNiro and another eGolf.

- 4 charging stops total, prices range from free (yay Aldi) to 0,79€/kwh (Ionity)

- only at the last stop did I notice significant slowdown of charge speeds, was getting 40 kw consistently, last charge seemed around 24 kw. So yes, the battery does heat up after 500 kms of driving and 4 charging stops, but at that point I’m bored of driving anyway so a longer break is welcome. It actually helps break the monotony of the journey down : 1,5 hr driving, 20 minutes charging, repeat.

-driving downhill at a constant speed gains you more mileage back than you lost going uphill. I don’t know why this is, but it meant shorter charging stops than I anticipated

- Contrary to what I was told, you dont need to plan ahead. Most if not all major highway services have many chargers available. Though it does help if you know a ‘backup’ charger (which I didn’t need)

All in all, a good day!

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NooDle

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18 degrees means 250ish kms on a charge. This one sparks joy.
 

NooDle

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My car in app finally looks like my car instead of either an ID3 or a white Golf with the wrong wheels.
I don’t know how they got the colour right, but I’m not complaining!
 

Galantti

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54f550d1c7d0505b955036c870504aae.jpg


My car in app finally looks like my car instead of either an ID3 or a white Golf with the wrong wheels.
I don’t know how they got the colour right, but I’m not complaining!

i am envious, mine just have white id3, but with correct wheels.
 

NooDle

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I know, software, but still. All of the options even down to the colour are hidden behind the VIN, so a simple database which tells you this car has colour x and wheels y shouldn’t be that hard?

It’s not like there’s a million different combinations either, you get like 5 colours and 3 wheel options…
 

WDWBen

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Maybe you just picked the wrong legacy car manufacturer…
 

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