Reasons to charge at 50% rate?

I just completed wiring a dedicated 230v circuit in the garage for charging. Now when powering up the charger, it defaults to 50% power, as is normal per the manual. My question is why would one want to charge at the 100% rate, unless, of course, you’re in a hurry.

One thing I know about rechargeable batteries is that, because of heat buildup, they generally don’t like to be charged at a fast rate. But the manual doesn’t advise one rate over the other. If one is not in a hurry to complete a charge, does the 50% rate make sense? It seems odd that the unit defaults to that setting at power up if that’s not the preferred rate, and after recovering from a power failure, that’s were it will be.

My thinking is that under normal overnight charging conditions, one might be better off charging at the slower rate. Another question. Will the climate control still come on and efficiently preheat/cool the cabin if the charger is set at this 50% rate? And how long does it take to charge at the 230v 50% setting. The manual doesn’t say.

Enquiring minds want to know.

Great question! I’d also like to know the answer!

Jbon":iihpnv4d said:

My question is why would one want to charge at the 100% rate, unless, of course, you’re in a hurry.

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From a system efficiency standpoint (highest percent of energy coming out of the wall winding up as useful capacity in the battery) charging quickly is more efficient than charging slowly, and charging Level 2 is more efficient than charging level 1.

The extra overhead of running the cars inverter longer, the control computers and the cooling system reduce the percentage of power that actually makes it into the car when you take longer to charge. This can be a big hit when charging on 120V at less than full amperage since the control/cooling systems use up the first few hundred watts of available charging power.

I base my comments on some testing Idaho National Labs did.

https://avt.inl.gov/project-type/vehicl ... em-testing

Sample findings for 2012 Volt, smallest battery they tested.

I hadn't thought about the charger system overhead. That makes some sense, though it doesn't appear to be a big hit. I wonder if the battery cares one way or another.