Electronics > Power/Renewable Energy/EV's

EV charging - More efficient at higher (48) or lower (32) amperage with L2?

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Please help me settle this debate - Is it more efficient to charge a Rivain or Tesla at a higher 48a or lower 323a with a L2 charger?  Is charging at a lower amperage easier on the batteries?

I have a Rivian and when I charge at 48 amp my garage get very warm from the EV charger and the charging cable is warm to the touch.  While charing I hear what I think is cooling pump motor running in the vehicle which I am guessing is used to cool the batteries while charging.

I am of the opinion the heat loss and having to cool the batteries is less efficient due to all of that wasted heat energy.  And charging at a lower amperage is much more efficient as there is less heat loss even though it might take a bit longer to charge.  I’m also thinking charing at the lower amperage is easier on the batteries and will prolong there life….  But it’s probably just a little.

My opposition is saying charging at a lower amperage is 75-80% efficient where charging at 48a is 94% efficient.  Opposition is also claiming that excess heat that’s warming the garage and pump cooling the batteries is negligible and can be ignored.  As for prolonging the life of the batteries the higher current doesn't make a difference.



The Soulman:
What does the first law of thermodynamics tell you?

You tell me.  What does it say about the efficiency and battery life?

Treez tier question.
7.5 to 10kw is tiny compared to the battery capacity, so your battery charge efficiency is probably steady between the two. How are the chargers in the vehicle cooled? Battery coolant circuit?
Also given the battery efficiency remaining steady, 50 percent more power in results in 50 percent more out. Do you really even care about efficiency? Or thermal loading and peak temperature in the battery?
Does anyone have any sources for any of these efficiency numbers? 7.5kw in at 75 percent efficiency seems unlikely in both terms of regulations, and feasibility of dumping almost 2kw out of the charger.

Here’s the thing.  If I charge at 48 amps the EVSE gets very warm and heats my garage to 80 degrees if not more.  If I charge at 30a there is no temperature  difference.  That wasted heat energy has to be reducing efficiency.  Which is why I’m asking.


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