Solved

Why does Kaluza app have a massive variation between the energy imported and exported even when the EV is connected 24h to the charger? Kaluza AMA


Userlevel 6
Badge +1

Kaluza app has a massive variation between the energy imported and exported even when the EV is connected 24h to the charger.

If that’s the level of loss - I am seriously out of pocket. If the data is incorrect then it should be correct. No one is expected to check the SMETS if they have an app/portal.

icon

Best answer by Tim_OVO 3 November 2020, 16:10

Here’s a short and sweet one from our Kaluza app product managerL

 

 

Hi @sylm_2000,

 

As both @philsquared and @TeaTimeSoon mentioned, the roundtrip losses are probably more than you might expect. We typically see about 10%. However, if you're seeing >20% difference, I would reach out to our support team to investigate. You can do so by emailing smarthome@ovoenergy.com.

 

Thanks,

Josh

View original

44 replies

Userlevel 2

Kaluza app has a massive variation between the energy imported and exported even when the EV is connected 24h to the charger.

If that’s the level of loss - I am seriously out of pocket. If the data is incorrect then it should be correct. No one is expected to check the SMETS if they have an app/portal.

In terms of energy I’ve been finding a 10-15% difference, which I understand is in line with what’s expected due to the inefficiency of charging and recharging a battery. If you’re seeing substantially different to that you should probably get it looked into.

Userlevel 3

Kaluza app has a massive variation between the energy imported and exported even when the EV is connected 24h to the charger.

If that’s the level of loss - I am seriously out of pocket. If the data is incorrect then it should be correct. No one is expected to check the SMETS if they have an app/portal.

Yes the losses are quite large, but are in line with expectations. I do think Kaluza could be more transparent about this BEFORE people sign up to the trial - it would be easy to think that what goes in will come out (or at least with only a few percent variation).

Userlevel 6
Badge +1

Kaluza app has a massive variation between the energy imported and exported even when the EV is connected 24h to the charger.

If that’s the level of loss - I am seriously out of pocket. If the data is incorrect then it should be correct. No one is expected to check the SMETS if they have an app/portal.

In terms of energy I’ve been finding a 10-15% difference, which I understand is in line with what’s expected due to the inefficiency of charging and recharging a battery. If you’re seeing substantially different to that you should probably get it looked into.

so here’s an example from the last few days (unable to take a download, error on Kaluza app, anyway). All 24 hours the EV has been connected to the V2G charger.

Day      i/p       e/p (kWh)

Thurs:  11.4     8.6

Wed:  11.7      8.6

Sat:     11.1       8.1

Tues   12.3    8.0

and the list goes on, it is an almost consistent trend everyday same trend for 24 hours cycle.

Statistically, I am having a 28% loss on a regular basis?? That’s just rather high to be considered efficient and smart charging model.

Userlevel 7

Here’s a short and sweet one from our Kaluza app product managerL

 

 

Hi @sylm_2000,

 

As both @philsquared and @TeaTimeSoon mentioned, the roundtrip losses are probably more than you might expect. We typically see about 10%. However, if you're seeing >20% difference, I would reach out to our support team to investigate. You can do so by emailing smarthome@ovoenergy.com.

 

Thanks,

Josh

Userlevel 6
Badge +1

Thanks @Tim_OVO 

 

I have sent an email as I am averaging at 25% loss on a monthly basis. Below is my summary for the last four months.

All units in kWh

Energy Imported

Energy Exported

EV Consumption

Consumption + Export

Loss

October 2020

398

217

90

307

91 or 23%

September 2020

333

170

70

240

93 or 28%

August 2020

336

213

36

249

87 or 26%

July 2020

337

240

13

253

84 or 25%

 

Userlevel 7

@sylm_2000 I know it’s not good stats here being reported, but it’s really handy to have this data available and laid out like this. Very interesting! 

 

I’m really keen to hear what you get back from that email. 28%.… that’s high. 

 

There might be some other trialists here that would be interesting in seeing this table above, and the reply to that email @D10hul @djriot @ArundaleP @Mikeyoung @aaronr @jp1 @Jequinlan @Andras - I’ve tagged you all as you were the top 8 exporters in this August competition...

Userlevel 7
Badge +2

My loss is much nearer 10% max . I burned roughly 100kwh on fuel in travelling in october:

 

 

So loss is trivial but not zero

Userlevel 4
Badge

@sylm_2000 Hi I’m pretty close to those figures too, although 28% does seem high.  I assumed everyone was getting similar.  Does that include electricity used in your house?  I assumed if my cooker and tumble dryer are on during 4-7pm then the house consumption could be a few kWh too?  I assume that the Energy Exported column is from the app not your meter?  @Tim_OVO would be nice to know what the net export is on the app too, would that be possible? or am I about to get a fright when you tell me it already is?

 

Most interesting was during lockdown when the car consumption was very low, I would still see losses of the same sort of order, see May for me

All units in kWh

Energy Imported

Energy Exported

EV Consumption

Consumption + Export

Loss

May 2020

266.6

204.4

6.5

210.9

55.7 or 20.89%

Userlevel 6
Badge +1

@sylm_2000 Hi I’m pretty close to those figures too, although 28% does seem high.  I assumed everyone was getting similar.  Does that include electricity used in your house?  I assumed if my cooker and tumble dryer are on during 4-7pm then the house consumption could be a few kWh too?  I assume that the Energy Exported column is from the app not your meter?  @Tim_OVO would be nice to know what the net export is on the app too, would that be possible? or am I about to get a fright when you tell me it already is?

 

Most interesting was during lockdown when the car consumption was very low, I would still see losses of the same sort of order, see May for me

All units in kWh

Energy Imported

Energy Exported

EV Consumption

Consumption + Export

Loss

May 2020

266.6

204.4

6.5

210.9

55.7 or 20.89%

 

thanks @jp1  the import and export measurement are from the kaluza app so should be directly linked to the EV. The consumption data is from Nissan EV app so reasonably reliable and reflects limited use in the months of lockdown and increased slightly in September and October. 

 

In the grand scheme of things it is about £20 per month but then again it is 25% of the energy lost when we focus on driving efficiency and sustainability. 

Userlevel 4
Badge

thanks @sylm_2000, that’s really disappointing, maybe I need to send an email to support too then

Userlevel 7

Send that email, @jp1 and please come back to update us. 

 

28% is higher then the standard and expected amount detailed by our expert Josh (above). 

 

Can anyone explain this from a technical perspective? Why is 10% normal? 

Userlevel 4
Badge

Yes @Tim_OVO just sent it, will try and remember to post back here

Userlevel 1

hi, I am getting similar figures. I sent this to support:-

3rd to the 11th sept our Leaf was permanently plugged into the V2G charger, climate timer was off. According to the app we exported 101Kw, imported 129 (78% efficient )I have a energy monitor on the V2G supply and that recorded 104Kw export 150Kw import.

 

they sent this reply:-

"Its because the car is left plugged in permanently - the efficiency loss is the LEAFs overhead of being powered on for 24 hours which is just over 1kWh per day. The ENV200 is much worse due to battery heating/cooling.

Standby consumption of V2G should be about 60W - might be worth the customer checking that.

 

Also, the discrepancy between his energy monitor and data in the app are because charger’s CT clamps may not be well calibrated, and there could be around 5% difference. This imprecision does not influence charging and exporting of the V2G. The customers smart meter is precise and they will be charged according to the smart meter readings not V2G's"

-----------

According to my energy monitor the V2G takes 50W when idle - so 1.2kW per day, and their stated LEAF loss of 1kW means there's a 2.2kW a day parasitic loss. Take those into account and the round trip efficiency is not bad, but the system as a whole isnt great.

It also means that if you unplug your car when its not charging, everything gets better, the V2G load when its off is 2W, and the car losses are much less.

 

Adam

 

Userlevel 6
Badge +1

@Josh_OVO , @Tim_OVO, @jp1 So this is the response I received today from the OVO customer care team. I think my query is not understood. Needless to say I have responded that I wished my monthly domestic electricity consumption was 100kWH but that’s not the case!

Await response.

 

“The difference between energy exported from the vehicle and energy exported from the property is due to energy consumption at the property. The amount of energy lost between exporting from the charger and exporting from the meter will vary from household to household depending on energy consumption.

We are able to measure the amount of energy exported from the vehicle and the amount exported from your property, and this is how we can tell how much energy is absorbed by the property before exporting. Unfortunately we have no control over the amount of energy your property absorbs, or any visibility as to why it absorbs as much as it does.”

Userlevel 6
Badge +1

@adz - agree however shouldn’t the energy consumption as measured by the Nissan EV app to include the idle or stand-by consumption therefore shouldn’t be outside the “consumption” reading. Marginal I agree of 1 to 2kW, still ...

 

 

Userlevel 4
Badge

Hi @sylm_2000, in case you were interested I got a response from Ashley (been useful before) today…

To better understand your usage, I have asked our Platforms team to pull the telemetry from your V2G for diagnosis. Once we've taken a look over this, we will be in touch to update you accordingly. 

 

In the meantime, could you please confirm where you are pulling the figures for your calculation from? In case you weren't aware, the figures shown in the app only show exports from the vehicle and do not account for property energy usage that is used prior to export from the grid.

will update when I get more news

Userlevel 7

Thanks for these posts, @sylm_2000 

 

I think the OVO Smart Home team might have an email from you, which is being looked into. So you can expect some account-specific advice shortly. As usual sharing the insights and conclusions here will help everyone. 

 

As for the advice from our Support team (which you quoted above), I can confirm it’s correct in saying that energy exported from your battery is used in property usage, with any excess counting as meter export. I must admit that I wasn’t aware of this until your post prompted me to double check!

 

 

Userlevel 6
Badge +1

Thanks @Tim_OVO - very helpful. 

Trying to understand the units reported in the Kaluza app and how it interacts with the home consumption as actuals.

It is all part of the trial and learning process, no problem. Look forward to explanation from the smart home team.

My overriding concern is if the energy loss is 25%, then we are definitely missing the objective on carbon emission and energy reduction. 

Userlevel 5
Badge +2

There are several reasons for round trip losses. It takes a certain amount of energy to keep the V2G charger connected to the vehicle and is fairly constant. There are losses incurred with the actual charging process (inverter efficiency, chemical efficiency of battery charging etc). 
I believe (but please don’t quote me) Indra are working on a lower power mode for the V2G charger itself which should produce some round trip efficiency gains. 

Userlevel 6
Badge +1

@ArundaleP , @Tim_OVO, @jp1 - heard back from the smart home team.

Been advised to complete a recalibration of the V2G charger so it can reset how it's reading the CT clamp data. 

Let’s see what happens following the investigation. I will revert back after the exercise. 

Appreciate your input.

 

 

Userlevel 4
Badge

Hi @sylm_2000, had a further response from the support team…

I'm getting in touch with an update on the round trip efficiency of your V2G charger.

We've monitored the round trip efficiency of your charger over a 7 day period from the 25th of October to the 31st of October. During this period the round trip efficiency was around 81.5%, meaning around 18.5% of the energy was lost.

The typical round trip efficiency of the V2G charger is between 80% and 90%, so this is within the range that we'd expect.

The round trip efficiency is dependent on different factors, including temperature and the rate at which charging/discharging occurs.

I hope this helps.

 

not sure if the period of time was cherry picked ;) but there you go, if the expected efficiency is 80%plus then I think I’m just about creeping into the expected range based on ad hoc observations I have made. 

 

Userlevel 7

Hi @sylm_2000 @jp1 @ArundaleP @adz @TeaTimeSoon @philsquared 

I’ve got an update on this from Mike Schooling, the founder and CTO of Indra:

 

There's some interesting changes in behaviour that come out of lockdown. I have personally seen efficiency drop below 90% when leaving the car plugged in all day. I was previously getting as good as 94% round trip when using the car - its plugged in for much less time when commuting.

 

Firstly. The app only shows the device metering - ignore the house loads and external CT for the data shown in the app. The external CT clamp is not used in any of the main data recording or logic/decision making for either the device firmware or Kaluza control. If of interest, the house CT data can be downloaded as a CSV in the app but beware it’s not calibrated for the trial units (we also have smart meter data so not necessary).

 

Efficiency of the unit should be around 90% round trip in typical use when the car disappears for several hours per day (e.g. to work).

 

Charging/discharging at low power is not good for efficiency, best to avoid the top 5% where current starts to drop (so bring charge range preferences down to 95%)

 

When plugged in for 24 hours, the standby consumption of the unit becomes a bigger problem - It's typically 30-60w when connected to the car but idle depending on when the unit was built. Indra has developed a deep sleep mode which is imminent and will power down the unit for long periods of inactivity to help address the standby consumption issue.

 

The car consumes around 1kWh per day when powered up but idle (e.g. when fully charged and connected to V2G.

 

I have no idea what is meant by recalibrating the V2G as advised by OVO Smart Home team. No calibration that affects the precision of data shown in the app is possible outside of the factory.

 

Best.

Mike

Founder and CTO at Indra

 

 

Userlevel 5
Badge

 Indra has developed a deep sleep mode which is imminent and will power down the unit for long periods of inactivity to help address the standby consumption issue.”

Can this be done with a software update? I` would like to see the deep sleep mode instead of idle when no charging or exporting happens for hours.

Userlevel 7
Badge +4

Hi,

I’ve just had a read through the reply that Tim posted from Indra. By the sounds of things, it should be possible to have the chargers pull down a software update that enables the deep sleep mode feature once it’s ready.

It’s a bit like how your computer goes to sleep if you leave it alone for a while and leaving it off for even longer makes it go into an even deeper power saving state and eventually (in some cases) completely turns itself off. It’ll still wake up when you want to use it, but won’t guzzle as much power in the meantime.

Back in the old days (such as in the 1990’s), even if a computer tried to shut itself down, you still had to press the off button yourself once you got a message like It is now safe to turn off your computer. I miss those days! These days however, most computers are able to flip the off switch themselves once the operating system has gotten into a safe state and you don’t get that message anymore.

Since I’m pretty confident that the chargers Indra makes behave more like the latter, this should (hopefully) work in a similar way.

In practice, it’s a bit more complicated than that, but I hope this helps with the concept.

Userlevel 5
Badge

Yes, that is correct. Round trip losses are somewhere around 15%, but there are also idle losses that are not insignificant. I think both the charger and the car draw about 1kW per day (and the former may not be fully reflected in the Kaluza app). 

That explains your numbers nearly perfectly:

12kW import

-2kW idle draw over 24h

-1.5kW (15% round trip losses)

8.5kW export

So while the round trip efficiency is 85%, the system efficiency is only 70%. Which is a bit meh.

I hope that the update comes out soon, because cutting those idling losses would really help quite a bit. The 15% are in the nature of power electronics, and it would be quite expensive to use high efficiency components. 

PS: Is it normal that the forum editor is flickering like a hummingbird? 

Reply