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Zoe ZE50 GT Line R135
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Discussion Starter #1
I got a bit of a shock when I was billed for 53kWh on a lamppost charger last week. Charging to full from ~17% SoC I was reckoning on 41.5kWh.

Somewhere in the back of my mind I kind of knew that charging inefficiency was an issue, but losing 28% is rather more than I was expecting! It makes the already-expensive 24p Ubitricity price even worse.

This was at 5kW. I think I remember reading the the Zoe was particularly bad at lower kW because of the 22kW AC capability.

Can anyone point me to some data? I found this blog about the previous model, but not sure how relevant it is to the ZE50, and I'd like to know what the DC losses are.
 

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I got a bit of a shock when I was billed for 53kWh on a lamppost charger last week. Charging to full from ~17% SoC I was reckoning on 41.5kWh.

Somewhere in the back of my mind I kind of knew that charging inefficiency was an issue, but losing 28% is rather more than I was expecting! It makes the already-expensive 24p Ubitricity price even worse.

This was at 5kW. I think I remember reading the the Zoe was particularly bad at lower kW because of the 22kW AC capability.

Can anyone point me to some data? I found this blog about the previous model, but not sure how relevant it is to the ZE50, and I'd like to know what the DC losses are.
Assumptions:
(1) 83% of a 52kWh usable battery gives 43kW needed to fill
(2) It was a 5kW lamppost supply

43/53 gives 81% efficiency. According to the results in the blog, that’s about right.
 
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Also it depends on the weather. If the car decided that to look after the battery it should heat or cool it using AC, that will reduce your efficiency further.
 

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had an R240, got an R90, might get a ZE50
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As you charged to 100% there would also be cell balancing at the end which is inefficient.

As regards DC does anybody really know whether the DC chargers measure the power and energy pre or post conversion, and are all charger types the same ?

Battery heating on the Zoé comes on when the battery is below 5 or 6 degrees C so shouldn't be relevant in UK at present.

From some limited testing I have done the rectification process not seems to have a constant loss of around 500W, so will be less than 90% efficient for 5kW.
 

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I got a bit of a shock when I was billed for 53kWh on a lamppost charger last week. Charging to full from ~17% SoC I was reckoning on 41.5kWh.

Somewhere in the back of my mind I kind of knew that charging inefficiency was an issue, but losing 28% is rather more than I was expecting! It makes the already-expensive 24p Ubitricity price even worse.

This was at 5kW. I think I remember reading the the Zoe was particularly bad at lower kW because of the 22kW AC capability.

Can anyone point me to some data? I found this blog about the previous model, but not sure how relevant it is to the ZE50, and I'd like to know what the DC losses are.
Here's a fairly technical paper on assessing losses during charging. Measurement of power loss during electric vehicle charging and discharging
Figure 1 shows the key components in the process.

I guess this is something home chargers mask unless they measure and display the electricity per charge too?
 

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Similiar to our ZE40, the car gets about 75% efficiency on a 7 Kwh home EVSE, 44.44 Kwh into the EVSE and the car recieved 33.15 Kwh into the battery according to the last charge I did on Sunday morning.
 

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Zoe ZE50 GT Line R135
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Discussion Starter #9
I guess this is something home chargers mask unless they measure and display the electricity per charge too?
Yes, it's the opaqueness that surprised me. It was only getting a bill for more than the size of my battery that alerted me. Even where the EVSE displays it, it not obvious unless you compare kWh at the meter to kWh in the battery.

My OHME tells me that it delivered 23kWh at a cost of £1.75 on Sunday, but it doesn't tell me that only 17kWh arrived in the battery!

Not OHME's fault of course, but it's not exactly in the EV sales brochure! So far the biggest gotcha I've discovered about EV ownership.

At 25% inefficiency, every mile I charge at home is a third more expensive than I thought.
 

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Yes, it's the opaqueness that surprised me. It was only getting a bill for more than the size of my battery that alerted me. Even where the EVSE displays it, it not obvious unless you compare kWh at the meter to kWh in the battery.

My OHME tells me that it delivered 23kWh at a cost of £1.75 on Sunday, but it doesn't tell me that only 17kWh arrived in the battery!

Not OHME's fault of course, but it's not exactly in the EV sales brochure! So far the biggest gotcha I've discovered about EV ownership.

At 25% inefficiency, every mile I charge at home is a third more expensive than I thought.
I agree it could be a gotcha. Most often quoted is the mi/kWh you see when driving the car, so the newbie lurking for information needs to get lucky and find a post or other source that explains the difference between what the car thinks internally and what your charger might say. Also, @E7EV recalculated your efficiency at 81% above. My rough calculations give me 85% going from 16% to 100% at 7kW.
 

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Made me think of ICE drivers who would raise the petrol pump pipe to get every last drop that they’d paid for! I wonder what percentage of every litre of bought petrol actually makes it to the cylinders.
 
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Made me think of ICE drivers who would raise the petrol pump pipe to get every last drop that they’d paid for! I wonder what percentage of every litre of bought petrol actually makes it to the cylinders.
That's true. Reminds me of this video about fuel efficiency for motorbikes.
 

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Zoe ZE50 GT Line R135
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Discussion Starter #14
At the risk of giving EV bashers more ammo,
Quite the opposite.

I think the EV world does itself more harm when it glosses over obvious downsides.

I thought I'd done my research. Knew which arguments (on both sides) to take with a pinch of salt. For example the 'well I have to stop every 2 hours anyway cos I need to pee' doesn't wash with me.

But I have to admit that 'home charging will cost a third more than you thought' comes as a surprise. I don't think many ICE drivers would put up with it if one in every four litres of petrol leaked out of the fuel hose, and the industry said 'yeah, that's how these fancy new hoses work. We didn't bother warning you though'.
 

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Good point. Even with the losses, EVs are still far cheaper to fuel and run. And I'm sure the losses will reduce as the battery tech improves.

It's a sad fact that moving electricity around incurs losses. From memory losses on the transmission and distribution networks are around 10% from power station to consumer. That's already built into your electricity price.
 
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