iV Battery Capacity vs Charging Confusion

[GarySN]

I’m confused. The battery capacity on the iV is 13kWh, yet when I charge it using the OVO Charge Anytime app, I see charging sessions well in excess of this, often to get the battery to 80% charge. The highest I’ve seen, for a full charge, is 78 kWh. I’m not complaining, as Charge Anytime credits my bill to apply a lower rate for all those kWhs, but I’m not sure what I’m missing.  Surely a full charge should be 13kWh?

[Warrior193]

Hello Gary - it would be around 13KWhr if the charging process was 100% efficient - which will not be the case.

Not sure what the actual charging efficiency of Lithium batteries is, but I would be more than disappointed if it was as low as that.

 

One thing to remember is - secondary batteries (of any chemistry) are not actually 'energy storage' devices - they generate electricity by a reversable chemical process.

 

Could the excess energy use be going towards pre-conditioning?  

Edited 8 November, 2023 by Warrior193
added information

[GarySN]

1 hour ago, Warrior193 said:

Hello Gary - it would be around 13KWhr if the charging process was 100% efficient - which will not be the case.

Not sure what the actual charging efficiency of Lithium batteries is, but I would be more than disappointed if it was as low as that.

 

One thing to remember is - secondary batteries (of any chemistry) are not actually 'energy storage' devices - they generate electricity by a reversable chemical process.

 

Could the excess energy use be going towards pre-conditioning?  

Thanks for the info. Your explanation re chemical process makes sense. The charging time has always been quoted as about 5 hours, which is how long mine takes (using a 3-pin plug), so I assume all is in order.  Just seems it’s costing me more than I’d realised. 

[MarkyG82]

Sounds like something is set up wrong with the charger wiring maybe.  A CT clamp in the wrong place or configured wrong.

Just seen your reply above and that you are using a granny cable.  It's worth you having a look on various forums on the benefits of using a wall box and the safety issues over using a granny cable.

That aside it may well be some preconditioning set wrong in the car that is constantly drawing from the grid.  Do you have anything you can look at the power consumption with to see when that power is being used?  78kw seems quite a lot.  That's the most our box can supply for 11 hours straight!!  Are you sure it's not 78kw over a week or more?

[Warrior193]

From a quick read on Google, lithium battery efficiency can be as low as 80% - up to a max. of over 95% - do you use battery or vehicle pre-heating - or are they available only on full BEVs?

Do you actually measure the units consumed during charging - or are you assuming max. current for full charge period?

[D402]

33 minutes ago, GarySN said:

The charging time has always been quoted as about 5 hours, which is how long mine takes (using a 3-pin plug)

Max power from a 13A socket is 3kW so it can't have used more than 3kW x 5 hours = 15kWh so I'd suspect a problem with the electricity meter or, more likely, the app. 

[GarySN]

34 minutes ago, MarkyG82 said:

Sounds like something is set up wrong with the charger wiring maybe.  A CT clamp in the wrong place or configured wrong.

Just seen your reply above and that you are using a granny cable.  It's worth you having a look on various forums on the benefits of using a wall box and the safety issues over using a granny cable.

That aside it may well be some preconditioning set wrong in the car that is constantly drawing from the grid.  Do you have anything you can look at the power consumption with to see when that power is being used?  78kw seems quite a lot.  That's the most our box can supply for 11 hours straight!!  Are you sure it's not 78kw over a week or more?

Definitely a figure for each charger by session…

 

[GarySN]

39 minutes ago, Warrior193 said:

From a quick read on Google, lithium battery efficiency can be as low as 80% - up to a max. of over 95% - do you use battery or vehicle pre-heating - or are they available only on full BEVs?

Do you actually measure the units consumed during charging - or are you assuming max. current for full charge period?

The car is capable of pre-heating, but I only ever use it when the car is plugged in.  I don't think this power would register on the app, as it controls when the car is charging, thus tracking what to the apply the lower tariff to.

Edited 8 November, 2023 by GarySN

[J.R.]

5 minutes ago, D402 said:

Max power from a 13A socket is 3kW so it can't have used more than 3kW x 5 hours = 15kWh so I'd suspect a problem with the electricity meter or, more likely, the app. 

 

You could pull 30 amps from a socket on a ring main although I'm sure the charger would limit the current to 3kw and be protected by a 13 amp fuse.

[GarySN]

9 minutes ago, D402 said:

Max power from a 13A socket is 3kW so it can't have used more than 3kW x 5 hours = 15kWh so I'd suspect a problem with the electricity meter or, more likely, the app. 

Thanks, that's the sort of knowledge I'm lacking.  Will check actual usage on my account.

[MarkyG82]

2 minutes ago, GarySN said:

Definitely a figure for each charger by session…

 

But how are those measured?  What physical equipment is installed to assess the power passing through your granny cable?  If those are figures from the app then is that talking to your car or via a smart plug?  Does it have a more detailed view than a simple total figure, like a start end end time and rate during that time?

[GarySN]

3 minutes ago, GarySN said:

Thanks, that's the sort of knowledge I'm lacking.  Will check actual usage on my account.

So the day-by-day usage on my account (for all electricity) is significantly lower than the Charge Anytime app is showing.  This is quite a relief!

 

[GarySN]

5 minutes ago, MarkyG82 said:

 

But how are those measured?  What physical equipment is installed to assess the power passing through your granny cable?  If those are figures from the app then is that talking to your car or via a smart plug?  Does it have a more detailed view than a simple total figure, like a start end end time and rate during that time?

As I understand it, the app is granted access to my Skoda Connect account, so can control when the car draws from the granny cable.  I had assumed the car could therefore tell the app how much it had consumed for any given session.

[MarkyG82]

Sounds like there is an issue with the backend somewhere which is causing the wrong data to be displayed.  The fact you are being charged the correct amount shows you are receiving the correct amount and that they are controlling it correctly.

I would report it as a bug and keep an eye on it.