Wall Connector Amp Setting

[DoubleACL]

I recently installed the signature Wall Connector and had planned to set the amperage to 40A since I have a 50A breaker on the line and had previously been using that line for a NEMA 14-50 wall outlet & achieving 40A+ charging speeds.

My father, a retired electrical engineer, recommended I set the WC at 32A because as long as I didn't need the faster overnight charging speed of 40A (which I don't) the 32A setting would improve the longevity of the charging components and battery as it produces less heat and stress, similar to the justification for "trickle charging" in many rechargeable battery chargers.

Does this principle have any validity or applicability to the Tesla WC & the Model S charging components/battery?

 

[davewill]

Not really. Both 40a and 32a are really slow for this enormous battery, and the wall connector is designed for 80a, so once again 40a is already a low rate. I'd go ahead and bump it back up, myself.

The other thing is that it makes more sense to dial the car down rather than the wall connector. That way if you suddenly need the higher rate, you can just dial it up in the car vs. opening up the wall connector and changing the setting.

 

[ucmndd]

The other thing is that it makes more sense to dial the car down rather than the wall connector. That way if you suddenly need the higher rate, you can just dial it up in the car vs. opening up the wall connector and changing the setting.

This. Set the WC to match the circuit. If you want to charge slower, adjust at the car.

 

[henderrj]

We have 168th K on our model S. Probably half the charging done on our wall connector at 80 amps. Haven't had a single problem of any sort. I think 32 to 40 amp isn't enough difference to amount to much. But I understand the principal for sure.

 

[Rocky_H]

My father, a retired electrical engineer, recommended I set the WC at 32A because as long as I didn't need the faster overnight charging speed of 40A (which I don't) the 32A setting would improve the longevity of the charging components and battery as it produces less heat and stress, similar to the justification for "trickle charging" in many rechargeable battery chargers.

Does this principle have any validity or applicability to the Tesla WC & the Model S charging components/battery?

As @davewill already said, it doesn't make sense to put that mechanical hard limit in your wall connector, because you can't change it easily later if you want to.

But let's look at that idea. There is a tiny grain of possible truth there, where power electronics running near their maximum rating can have significant heat, and heat cycling can be hard of the lifetime of electronics. But let's see if it's applicable:

1. Wall connector--they are made to run up to 80A maximum, so 40 or 32 is already lots of margin--not applicable.
2. Internal charger in the car--Do you have a relatively new Model S with the 48 amp charger? If so, then 40 or 32 are already leaving margin, so not applicable. If it were an older S with the 40A charger, then maybe, but you could turn that down a little bit in the car if you want.
3. Battery--definitely not. The batteries can take Supercharger rates of over 100kW of power. You're talking about messing around with the difference between 7 or 10kW. It's all so low that the battery won't care in the least.

 

[DoubleACL]

2. Internal charger in the car--Do you have a relatively new Model S with the 48 amp charger? If so, then 40 or 32 are already leaving margin, so not applicable. If it were an older S with the 40A charger, then maybe, but you could turn that down a little bit in the car if you want.

Not a newer Model S -- Dec '17 Model S, 2.0. I set the WC at #8 for 40A on a 50A max circuit; will set down to 32A for everyday use, and kick it up if I'm feeling the need for speed.

Appreciate all the great answers & hope this discussion might help others as well contemplating the same question. /DoubleACL