Charging efficiency

[fshuk1]

I am charging my SE SR car using granny cable at home. My electricity use shows 2.3kW being used. My iSmart app shows 1.87kW charging power. This is a loss of 19%. My question is if you charge using the granny chargers what does your iSmart show as charging power and also what is your efficiency rate?

 

[Ayoull]

Efficiency rating is effected by ambient temperature of the air and of your battery and charger in the car.

What you're seeing in ismart is the final unit input after all losses are taken into account from the point of your charger that is pulling 2.3kW

This diagram gives you a rough idea of efficiencies of different "fuel" types

 

[BrenEV]

I always find it interesting that charging efficiency is rarely discussed when comparing running costs of EVs to ICE.

If you’re losing 15-20% of the energy being taken from the grid, that significantly increases the real running cost of the vehicle, but all of the discussion is just about the cars m/kwh figure usually.

 

[fshuk1]

I am fully committed to electric cars. Apart from the fact that they are much much nicer to drive, they emit no co2.
Now that we have our MG4s I was interested in what other people are getting to see if there is a problem to fix or it is what it is.

 

[Jomarkh]

Hi, is the 2.3kWH draw including the house load on your IHD?
If the car has not been used then the battery will be cold and the outside temperature is cold, there are more power losses in the cold weather.

 

[siteguru]

The efficiency of the converter in the car (AC to DC) is not linear vs the input power. There are some fixed losses in the converter (as well as variable losses based on power) thus the overall efficiency is worse at lower power than it is at higher power.

So 81% efficiency off a granny charge cable is not bad. (I get about 92% efficiency off my 7kW wall box).

 

[Oberoy]

Yeah I'm getting aroun 10-12% losses generally, one charge it was up to 22% I could have noted something wrong on that charge though to cause the anomalie

 

[Tigger]

So 81% efficiency off a granny charge cable is not bad. (I get about 92% efficiency off my 7kW wall box).

Interesting. On one test I did on my Trophy, my Pod Point charger was delivering about 6.6kw, while the car registered 6.2kw, so efficiency 94%. However, it is difficult getting the gross figure right, because I have to subtract other electrical activity in the house from the meter reading.

 

[siteguru]

In my case I just compare the total charge as calculated for the car ([end% - start%] x usable battery capacity) vs total charge as recorded by my Wallbox app.