LeafSpy, Charger efficiency and other questions

KCross · 18-08-2016 11:20am #1

I've recently got my home charger up and running. Its a 32A Rolec and I have the 6.6kW charger in the car which is a 24kWh LEAF.

I also have a kWh meter connected on the fuseboard side of the charger so I can keep a track of how much electricity the car is using.

I've been tracking the electricity used versus the charge in the car and its thrown up a few questions which maybe someone can answer.

a) The car was down to VLBW (8%). LeafSpy said it had 1.9kWh's left, 24 GIDS and SOC was 15.6.

b) I charged it to 100% and LeafSpy gave me 21.7kWh's, 280 GIDS and SOC was 97.3

c) The kWh meter showed I had used 20.59kWh's for that charge which includes any charger inefficiency.

d) LeafSpy is reporting SOH as 100% and Hx of 99% with 18k km's on the clock (151 car).

Questions:

1) Why the large difference in the car % and the LeafSpy SOC percentages in a) and b).
In a) there is an 8% difference. In b) its only 3%. Why?

Some rough figures suggest to me that the 8% is more accurate. If the figure of 1.9kWh's is right that is almost exactly 8% of 24kWh's which is the max of the car. I cant figure out where 15% can come from even if I allow for the fact the car has only 21kWh's usable?

2) By my figures I used 20.59kWh's of electricity to put 19.8kWh's into the car which gives a charger efficiency of 96%. I thought I read somewhere that the chargers were only 90% efficient. Have I misinterpreted something here?

3) The charge graph on LeafSpy showed the car pulling 6kW's exactly, not 6.6kW. Is this normal? Why do they say it is a 6.6kW charger if its not utilising 6.6kW's? What do other folks on here see their cars using on that graph when connecting to their home charger?

4) I use the timer to charge the car at night. However, I have noticed that when I plug it in it goes through some initialisation process for a second or two (I presume validating the charger connection) and then it goes quiet until the timer kicks in. Thats all fine. However, I notice on LeafSpy that my L1/L2 figure is incrementing by 2!

This is going to make it look my car has done twice as many home charges as I have actually done. Thats not good for resale!

I'd be interested in someone else who has LeafSpy trying this out. If its just me I need to see if its a EVSE or car issue.

BoatMad · 18-08-2016 3:44pm

Good questions. I have a 6k6 leaf with 30 kWh and a 32A evse. I must put my leafspy to use and see what numbers I am getting

BoatMad · 18-08-2016 3:48pm

Good questions. I have a 6k6 leaf with 30 kWh and a 32A evse. I must put my leafspy to use and see what numbers I am getting

KCross · 18-08-2016 10:31pm

KCross wrote: »

4) I use the timer to charge the car at night. However, I have noticed that when I plug it in it goes through some initialisation process for a second or two (I presume validating the charger connection) and then it goes quiet until the timer kicks in. Thats all fine. However, I notice on LeafSpy that my L1/L2 figure is incrementing by 2!

This is going to make it look my car has done twice as many home charges as I have actually done. Thats not good for resale!

I'd be interested in someone else who has LeafSpy trying this out. If its just me I need to see if its a EVSE or car issue.

Looks like this is the way it works!!!!!

https://speakev.com/threads/the-battery-health-thread.18923/#post-329925

That's a bad software error on Nissans part and very misleading for resale.

Interesting to know if this bug is fixed in you '16 car BoatMad?

cros13 · 18-08-2016 11:40pm

I wouldn't worry about it impacting resale value. It's the recorded L3 charges that people are really looking at.

The number of L2 charging events has no bearing on the condition of the battery.

19-08-2016 10:06am

KCross wrote: »

c) The kWh meter showed I had used 20.59kWh's for that charge which includes any charger inefficiency.

Be sure your power meter has power factor correction, this can have a big impact on Kwh meters.

KCross wrote: »

d) LeafSpy is reporting SOH as 100% and Hx of 99% with 18k km's on the clock (151 car).

My 151 with 45,600 Kms has 93-96% health, I drive it pretty hard and have to charge it more often as a result. At about 1 Kwh you will enter Turtle mode.

KCross wrote: »

1) Why the large difference in the car % and the LeafSpy SOC percentages in a) and b).
In a) there is an 8% difference. In b) its only 3%. Why?

The BMS hides about 7% from you as kind of a reserve, that 7% should get you about 35-40 kms at 80-100 Kph. But be warned, when the battery charge % gets low it can go from 12% for example to --- very quickly if you (suddenly) drive it very hard, or harder.

The reason is because not all cells are equal some will reduce voltage quicker than others and the BMS will have to catch on to this and think the battery has less capacity but if you drive gently at low battery warning you will get more kms before the display shows --- because these cells won't be under as much stress and won't dip in voltage so fast. You can clearly see this voltage dip on leafspy when the battery % is low and you suddenly put the boot down.

KCross wrote: »

2) By my figures I used 20.59kWh's of electricity to put 19.8kWh's into the car which gives a charger efficiency of 96%. I thought I read somewhere that the chargers were only 90% efficient. Have I misinterpreted something here?

It's about 90% but not sure how accurate this is, again you need a Kwh meter with power factor correction. Perhaps you already do.

KCross wrote: »

3) The charge graph on LeafSpy showed the car pulling 6kW's exactly, not 6.6kW. Is this normal? Why do they say it is a 6.6kW charger if its not utilising 6.6kW's? What do other folks on here see their cars using on that graph when connecting to their home charger?

6 Kw is what's going to the battery the rest is lost in heat.

KCross wrote: »

4) I use the timer to charge the car at night. However, I have noticed that when I plug it in it goes through some initialisation process for a second or two (I presume validating the charger connection) and then it goes quiet until the timer kicks in. Thats all fine. However, I notice on LeafSpy that my L1/L2 figure is incrementing by 2!

I haven't noticed this will check it when I'm off shift next Thursday.

KCross · 19-08-2016 10:45am

Deleted User wrote: »

Be sure your power meter has power factor correction, this can have a big impact on Kwh meters.

I have documentation with it which gives its accuracy class as "Class B".
Does that mean anything?

Deleted User wrote: »

The BMS hides about 7% from you as kind of a reserve, that 7% should get you about 35-40 kms at 80-100 Kph. But be warned, when the battery charge % gets low it can go from 12% for example to --- very quickly if you (suddenly) drive it very hard, or harder.

So, it looks like it hides more and more of it as the battery runs down.

Deleted User wrote: »

It's about 90% but not sure how accurate this is, again you need a Kwh meter with power factor correction. Perhaps you already do.

How did you determine it was 90%? Is it just what they have in the chargers documentation? What charger do you have? Maybe Rolec are better?

Deleted User wrote: »

6 Kw is what's going to the battery the rest is lost in heat.

I'm skeptical on that answer.

I dont think the kWh figures I've given back up that suggestion.

If what you are saying were true you are saying that it is actually pulling 6.6kW's but the battery is only taking 6kW's onboard. So, thats a 10% loss at the car end plus you are saying another 10% loss at the charger end.... I'm definitely not losing 20%!

Also, I have another kWh meter on the main spur coming into the house (so it includes everything) and it does not show more than 6.6kW's when the car is charging. If the car were pulling close to 6.6kW's the main spur would be showing close to 7kW's and its not.

I think the car is pulling 6kW's and no more. i.e. LeafSpy is correct.

I'd be interested to see what others see on their cars.

KCross · 19-08-2016 10:49am

cros13 wrote: »

I wouldn't worry about it impacting resale value. It's the recorded L3 charges that people are really looking at.

The number of L2 charging events has no bearing on the condition of the battery.

I agree in general as the SOH, mileage, condition, age are more important.

However, doesnt Nissan's battery report utilise these figures to give you the "star rating".

I know that star rating report is close to useless but for someone who doesnt know about batteries or LeafSpy they will put alot of weight to Nissan's report and that then could affect resale. Perception is reality and all that?!

Either way, its a bad software error. I hope they have it fixed for MY16 cars.

19-08-2016 3:22pm

KCross wrote: »

I have documentation with it which gives its accuracy class as "Class B".
Does that mean anything?

No not to me, but I do think if it has power factor correction that it would tell you somewhere on the unit, mine does. This is important.

KCross wrote: »

So, it looks like it hides more and more of it as the battery runs down.

No , Leafspy reports the Real SOC, your dash display reports around 7% less, but at certain %, I think but don't quote me on this this that at higher charge % leafspy will report the charge % to be around the same as the dash it's only when you go low as in 30-40% it shows you got less, this is a kind of a reserve. that when it shows --- you got some left in the tank but by --- you better be pretty damn close to home or a charge point.

KCross wrote: »

How did you determine it was 90%? Is it just what they have in the chargers documentation? What charger do you have? Maybe Rolec are better?

I'm talking about the charger in the car, the EVSE or home charge point isn't a charger at all, it jsut supplies the power. It's a bit like an advanced socket if you like.

KCross wrote: »

If what you are saying were true you are saying that it is actually pulling 6.6kW's but the battery is only taking 6kW's onboard. So, thats a 10% loss at the car end plus you are saying another 10% loss at the charger end.... I'm definitely not losing 20%!

Yes the car charger is pulling about 6.6 Kw from the mains and dumping about 6 Kw into the battery. It's about 90% efficient. So 6 + 10% = 6.6 Kw.

KCross wrote: »

Also, I have another kWh meter on the main spur coming into the house (so it includes everything) and it does not show more than 6.6kW's when the car is charging. If the car were pulling close to 6.6kW's the main spur would be showing close to 7kW's and its not.

I think you read what I was saying wrong or I could have explained better.

KCross wrote: »

I think the car is pulling 6kW's and no more. i.e. LeafSpy is correct.

Just to be clear, leafspy is showing what is going into the battery, the same at the fast charge locations, it will show less going into the car than is reported by some newer triple headed fast chargers. These charger Kw displays show the consumption in total, that is, what is the output to the car including losses which is losses in the charger itself.

19-08-2016 3:22pm

KCross wrote: »

I have documentation with it which gives its accuracy class as "Class B".
Does that mean anything?

No not to me, but I do think if it has power factor correction that it would tell you somewhere on the unit, mine does. This is important.

KCross wrote: »

So, it looks like it hides more and more of it as the battery runs down.

No , Leafspy reports the Real SOC, your dash display reports around 7% less, but at certain %, I think but don't quote me on this this that at higher charge % leafspy will report the charge % to be around the same as the dash it's only when you go low as in 30-40% it shows you got less, this is a kind of a reserve. that when it shows --- you got some left in the tank but by --- you better be pretty damn close to home or a charge point.

KCross wrote: »

How did you determine it was 90%? Is it just what they have in the chargers documentation? What charger do you have? Maybe Rolec are better?

I'm talking about the charger in the car, the EVSE or home charge point isn't a charger at all, it jsut supplies the power. It's a bit like an advanced socket if you like.

KCross wrote: »

If what you are saying were true you are saying that it is actually pulling 6.6kW's but the battery is only taking 6kW's onboard. So, thats a 10% loss at the car end plus you are saying another 10% loss at the charger end.... I'm definitely not losing 20%!

Yes the car charger is pulling about 6.6 Kw from the mains and dumping about 6 Kw into the battery. It's about 90% efficient. So 6 + 10% = 6.6 Kw.

KCross wrote: »

Also, I have another kWh meter on the main spur coming into the house (so it includes everything) and it does not show more than 6.6kW's when the car is charging. If the car were pulling close to 6.6kW's the main spur would be showing close to 7kW's and its not.

I think you read what I was saying wrong or I could have explained better.

KCross wrote: »

I think the car is pulling 6kW's and no more. i.e. LeafSpy is correct.

Just to be clear, leafspy is showing what is going into the battery, the same at the fast charge locations, it will show less going into the car than is reported by some newer triple headed fast chargers. These charger Kw displays show the consumption in total, that is, what is the output to the car including losses which is losses in the charger itself.

19-08-2016 3:25pm

Bear in mind there is also some battery that is hidden by the car's BMS there is some of the battery top and bottom that is reserved to prolong life.

This won;t be seen by Leafspy nor the car's dash. Leafspy reports all that is available and that is about 21-22 Kwh on a new battery.

Some people think that as the battery ages the BMS will open up some of this hidden capacity, but that is just guessing, I guess noone will really ever know this.

KCross · 19-08-2016 4:37pm

Deleted User wrote: »

KCross wrote: »

I have documentation with it which gives its accuracy class as "Class B".
Does that mean anything?

No not to me, but I do think if it has power factor correction that it would tell you somewhere on the unit, mine does. This is important.

I cant tell if it has it or not. Its installed so I'm not pulling it out of the rail to look at it.

Deleted User wrote: »

No , Leafspy reports the Real SOC, your dash display reports around 7% less, but at certain %, I think but don't quote me on this this that at higher charge % leafspy will report the charge % to be around the same as the dash it's only when you go low as in 30-40% it shows you got less, this is a kind of a reserve. that when it shows --- you got some left in the tank but by --- you better be pretty damn close to home or a charge point.

I think we are saying the same thing here. At 100% the dash and LeafSpy are almost in sync. As you run the battery down the dash "hides" more and more of it as a reserve. LeafSpy continues to display real SOC. Makes sense.

Deleted User wrote: »

Yes the car charger is pulling about 6.6 Kw from the mains and dumping about 6 Kw into the battery. It's about 90% efficient. So 6 + 10% = 6.6 Kw.

If 6.6kW's is being pulled I am wondering why I dont see more than that on my main kWh meter.

And it would also mean that both my kWh meters are lying... i.e. this power factor thing you talk about. Thats possible I suppose.

I'll run a few more tests.

I presume the main ESB meter box is accurate?! I'll do some cross checks against that.

19-08-2016 5:03pm

KCross wrote: »

If 6.6kW's is being pulled I am wondering why I dont see more than that on my main kWh meter.

And it would also mean that both my kWh meters are lying... i.e. this power factor thing you talk about. Thats possible I suppose.

I never see 3.3 Kw being pulled from my power meter either because of the other loads in the house , mine is connected direct to the meter but it looks to be pretty close.

So to clarify, do you have a power meter connected direct to your home charge point ? and also one on the live feeding the ESB meter ?

KCross · 19-08-2016 5:13pm

Deleted User wrote: »

I never see 3.3 Kw being pulled from my power meter either because of the other loads in the house , mine is connected direct to the meter but it looks to be pretty close.

So to clarify, do you have a power meter connected direct to your home charge point ? and also one on the live feeding the ESB meter ?

Correct, I have two power meters plus the ESB meter itself... so thats 3 actually!

Why dont you see 3.3kw being drawn? You should see 3.3 plus whatever the house is using which will be at least a few hundred watts more just for pliot lights, fridge etc. If you are seeing less than 3.3 then the car isnt drawing it.

19-08-2016 5:41pm

KCross wrote: »

Correct, I have two power meters plus the ESB meter itself... so thats 3 actually!

Why dont you see 3.3kw being drawn? You should see 3.3 plus whatever the house is using which will be at least a few hundred watts more just for pliot lights, fridge etc. If you are seeing less than 3.3 then the car isnt drawing it.

Yeah exactly, I see 3.3 + the few hundred but don't know exactly and the house kw varies all the time. The meter itself updates every about 6 seconds.

KCross · 19-08-2016 5:57pm

Deleted User wrote: »

I never see 3.3 Kw being pulled from my power meter either because of the other loads in the house , mine is connected direct to the meter but it looks to be pretty close.

So to clarify, do you have a power meter connected direct to your home charge point ? and also one on the live feeding the ESB meter ?

Deleted User wrote: »

Yeah exactly, I see 3.3 + the few hundred but don't know exactly and the house kw varies all the time. The meter itself updates every about 6 seconds.

It cant be both!

19-08-2016 6:33pm

KCross wrote: »

It cant be both!

lol, no you don't get me.

I see 3.3 + the additional house consumption but can't determine the exact load from the car.

So in other words It appears as if an extra 3.3 kw are being pulled but it's hard to get the exact.

cros13 · 19-08-2016 7:27pm

BoatMad · 25-08-2016 12:26pm

Just a comment here folks

1. KW meters do not have " power factor corrections", they cant as they dont know the power factor , Good ones can read both the KW and KVA and determine KvarW ( often known as wattless power) and hence report on the average power factor. IN domestic situations you are measured for KW, i.e. reactive power is not taken into account , but the power factor of most homes is close to 1 ( 0.97- 0.99) anyway and the esb monitor the situation

most cheap KW and KWH meters as built to meet or exceed Class1 EN60136, ( I dont know what class B is ) . These again are KW and KWH meters they do not measure reactive power. ( i.e. the same as the esb meter)

There are several reasons for the anomalies

1. The accuracy of cheap KWH meters can be questionable especially in the face of harmonics on the AC line , furthermore if you are using a clip on current transformer ( or an similar internal arrangement) your measurements can be off by over 10 %

2. unless you know the providence of all the measurements including the accuracy of Leafspys ( i.e. nissans)measurements, it would be impossible to deduce accuracies any further

3. The power factor of the Nissan charger is reported as 0.99 , so reactive power isn't an issue ( and anyway you are not measuring it anyway )

4. There is an outside chance that your EVSE is set to a slightly lower duty cycle then 6kw6 and hence the car is not drawing full current. personally its unlikely though

as an aside , unless you have a logging KW meter, all you are doing to determine KWH and deducing KW and Amps is , taking the KWH over time and comparing it to Leafspy, there is easily an accumulation of errors there that could easily exceed 10% or more

and without a detailed spec, its impossible to say whether the Leafs 6kw6 charger specifications is an input power or output power specification. The discussion on MyNissan Leaf, seems to suggest that a percentage of the charger output is used to maintain the 12V dc dc convertor , hold in the high voltage contractors, so without any spec , its impossible to determine exactly whats going on

for further info http://www.mynissanleaf.com/viewtopic.php?t=8583 ( a bit dated now)

BoatMad · 25-08-2016 12:35pm

folks, this is an interesting study on a modern leaf http://www.mynissanleaf.com/viewtopic.php?t=8583 you'll notice they measured the power at the charger output , not on the onboard nisssan measurements

its worth noting that efficiency decreases as charge rate decreases ( this is a characteristic of switched mode convertors ) , so the efficiency is not linear over the charge time. Hence trying to compare average power consumptions will be fraught with issues

Id say getting within 10% testing accuracy is good going

KCross · 25-08-2016 1:19pm

I'll answer some of my own questions here after some additional "testing".

KCross wrote: »

1) Why the large difference in the car % and the LeafSpy SOC percentages in a) and b).
In a) there is an 8% difference. In b) its only 3%. Why?

As discussed earlier in the thread, the Dash SOC "hides" some of the charge, as a reserve, as the charge decreases.

KCross wrote: »

2) By my figures I used 20.59kWh's of electricity to put 19.8kWh's into the car which gives a charger efficiency of 96%. I thought I read somewhere that the chargers were only 90% efficient. Have I misinterpreted something here?

After doing a few more tests I am getting varying results which concurs with @BoatMad saying the efficiency isnt linear. I'm getting anything from 90% to 96%. I think the 96% is the least accurate as I only put in 1kWh as a short test. On the longer overnight charges I'm getting around 93%. Thats probably closer to the truth. I'm going to gather a few more samples and see what the average is like.

I'll accept that I'll never get a 100% accurate figure but it should be reasonably accurate.

FYI: I'm not using a clip on meter. Its a DIN rail type meter. Fortunately in the Rolec chargers there is space on its DIN rail next to the MCB to fit one other device so I stuck the kWh meter in there. See pic.

KCross wrote: »

3) The charge graph on LeafSpy showed the car pulling 6kW's exactly, not 6.6kW. Is this normal? Why do they say it is a 6.6kW charger if its not utilising 6.6kW's? What do other folks on here see their cars using on that graph when connecting to their home charger?

I see the same output in LeafSpy when connecting to the ESB standard chargers as well. LeafSpy never shows 6.6kw's being pulled so its not my EVSE.

KCross wrote: »

4) I use the timer to charge the car at night. However, I have noticed that when I plug it in it goes through some initialisation process for a second or two (I presume validating the charger connection) and then it goes quiet until the timer kicks in. Thats all fine. However, I notice on LeafSpy that my L1/L2 figure is incrementing by 2!

This is going to make it look my car has done twice as many home charges as I have actually done. Thats not good for resale!

I'd be interested in someone else who has LeafSpy trying this out. If its just me I need to see if its a EVSE or car issue.

I see the same issue when connecting to ESB standard chargers so its not my EVSE. Its how the Leaf works when you use the timer. So, beware when you try to interpret the L1/L2 figures as they can vary by a factor of 2 depending on whether the user is using the cars timer or not.

BoatMad · 25-08-2016 1:27pm

The DDS 253 KWH meter is a cheap Chinese job and Id question if its accuracy is better then 10%

secondly how are you measuring the KW the charger in the car is taking , how are you determining peak power, if you are just relying on Leafspy, then we know that a certain percentage of the charger output is lost in powering up the cars systems ( see the MYnissan thread)

Again, I think your conclusions are a function of inaccurate data and lack of specifications , rather then anything else

I see the same issue when connecting to ESB standard chargers so its not my EVSE. Its how the Leaf works when you use the timer. So, beware when you try to interpret the L1/L2 figures as they can vary by a factor of 2 depending on whether the user is using the cars timer or not.

This however is a serious error

KCross · 25-08-2016 1:51pm

BoatMad wrote: »

The DDS 253 KWH meter is a cheap Chinese job and Id question if its accuracy is better then 10%

Cheap chinese.... I cant agree or disagree with you!!

BoatMad wrote: »

secondly how are you measuring the KW the charger in the car is taking , how are you determining peak power, if you are just relying on Leafspy, then we know that a certain percentage of the charger output is lost in powering up the cars systems ( see the MYnissan thread)

I'm not claiming to be an electrical engineer with high tech equipment to match the folks on that thread you posted. I'll admit this is relatively rudimentary. I am relying on the kWh meter and LeafSpy. Either/both of those could be wrong. I'm not claiming otherwise.

Just reading the data and posting the question for feedback.

BoatMad wrote: »

Again, I think your conclusions are a function of inaccurate data and lack of specifications , rather then anything else

I feel like Pat Hickey now.... I'm "back in my box"!

BoatMad wrote: »

This however is a serious error

Did you confirm if this happens for you on your MY16 Leaf?

BoatMad · 25-08-2016 3:18pm

KCross wrote: »

Cheap chinese.... I cant agree or disagree with you!!

They are widely available on aliexpress.com ( under different branding ) for about $8 , they are claimed to be Class 1 , which is +-1.5%

Im not trying to be snooty, just that with the lack of specifications and the inherent inaccuracies of using KWH, you ( or I ) could easily come to inaccurate conclusions about power consumption

Did you confirm if this happens for you on your MY16 Leaf?

no not yet , but I must be interesting to see id the L1/L2 count is wrong

( arguably it would actually serve to improve the "stars" rating , not disimprove it )

samih · 25-08-2016 4:19pm

BoatMad wrote: »

Im not trying to be snooty, just that with the lack of specifications and the inherent inaccuracies of using KWH, you

Kelvin Watt Hydrogen?

BoatMad · 25-08-2016 7:24pm

samih wrote: »

Kelvin Watt Hydrogen?

Forgive my poor capitalisation KWh, kilowatt hour or a " unit " of electricity for the common man explanation !!!!!

As opposed to KVAh or KvarWh !!!

cros13 · 26-08-2016 12:16am

BoatMad wrote: »

The accuracy of cheap KWH meters can be questionable especially in the face of harmonics on the AC line , furthermore if you are using a clip on current transformer ( or an similar internal arrangement) your measurements can be off by over 10 %

In my case I use a 40A inline smart switch with metering. I use an optical meter on the ESB (and gas and water meters) and I have a second 63A inline meter/switch for the house supply. I've done a rough calibration in software where the sum of the values received from the two high amperage switch units every second are compared over a 7200 minute period against the ticks returned from the optical meter on the ESB meter. I have some metering as well back from sockets and switches about the house.

Lots of flaws in the setup, it's all a bit too relative. But largely handles what I care about.... what I'm being charged for and what proportion can be attributed where.

BoatMad · 30-08-2016 5:24pm

cros13 wrote: »

In my case I use a 40A inline smart switch with metering. I use an optical meter on the ESB (and gas and water meters) and I have a second 63A inline meter/switch for the house supply. I've done a rough calibration in software where the sum of the values received from the two high amperage switch units every second are compared over a 7200 minute period against the ticks returned from the optical meter on the ESB meter. I have some metering as well back from sockets and switches about the house.

Lots of flaws in the setup, it's all a bit too relative. But largely handles what I care about.... what I'm being charged for and what proportion can be attributed where.

I was merely pointing out that errors in current measurement , Unknown charger efficiency curves and other data make it impossible to deduce the conclusions that were reached ( or attempted to be reached )

I measure my cars KWh Consumption, I don't expect to be better then 90% accurate.

KCross · 19-09-2016 3:22pm

I dont do rapid charges too often but I did one over the weekend and I took some figures off the rapid charger before and after.

It put in 14.35kWh's in 24mins and LeafSpy showed it took in 12.9kWh which gives an efficiency of 89.9%. The charger itself also gives an efficiency figure which matched that figure of 89%.

Question.... would a lower powered charger (i.e. EVSE) be more efficient as there would be less heat given off at lower power?

Presumably there is an efficiency sweet spot somewhere whereby increasing power reduces efficiency?

19-09-2016 10:18pm

Probably higher voltage would be more efficient, would require less current which generates less heat and is less stressful on components and one reason VW want to go I think with 800 volts for 300 Kw , that's a long way off.

I used the charger in Wicklow Town last week and it said 61 Kw on the power meter, I never seen those triple headed chargers pull that before, but the battery was warm enough and I never recorded what leaf spy said was going to the battery.

BoatMad · 19-09-2016 10:31pm

I used the charger in Wicklow Town last week and it said 61 Kw on the power meter, I never seen those triple headed chargers pull that before, but the battery was warm enough and I never recorded what leaf spy said was going to the battery.

hmm, it is a fast one I notice ( and that charger was a nice quite unused secret , but not any longer )

LeafSpy, Charger efficiency and other questions

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