What is the most efficient charging power?

[zdre]

Does anyone know what is the most efficient charging power for a single charger?
From my experience with computer power supplies, the highest efficiency is achieved at around 50% load.
The issue is that we don't know how much the Model S charger's max load of 10kW is already de-rated from the real maximum.
It would be great if Tesla provided an efficiency curve for the Model S chargers like the one below:

 

[schueppert]

I have seen charts like that for PC power supplies too. I believe more efficient modern designs tend to retain their highest efficiency up to much higher loads. In Model S you also have to consider that charger losses are about equal in magnitude to internal battery losses, and these battery losses are probably proportional to current. I suspect these two effects more or less cancel out so that efficiency doesn't vary too much with charging power. But as you say, it would be nice to have some real data.

 

[stopcrazypp]

Your overall charging efficiency will depend on your wiring for your charger too (since you care about from the meter to your car, not just from the charging socket). So even if you find the most efficient point for the onboard charger, that's not necessarily the same overall.

So it'll probably trend somewhere slightly lower than the most efficient charging load.

 

[markwj]

This has been discussed in a few threads.

Conclusion was that you need to balance the efficiency of the charging system against the use of HVAC and fans during charging. Lower currents are more efficient from an electrical losses point of view, but HVAC/fan losses are greater. Depending on individual situation, electrical losses from meter to vehicle may also be significant,

Charging in High Temperature environments 13A vs 32A vs 70A: cost of air conditioning
You might consider charging slower

(Edit: to add links to relevant threads)

 

[darthvdr]

This was very informational for me.

[url]http://www.teslamotorsclub.com/showthread.php/17152-What-should-my-ideal-charge-percentage-be-(FWv4-5)[/URL]