Should you charge slower with your wall charger in the summertime?

[tnt1971]

Really interesting data from Sorka. I have a 2016, with a max of 40 amp on one inverter. I charge at 30 most of the time to put less strain (and heat) on the inverter. I understand they go and I plan on keeping my car for 5-6 years. I did not buy the extended warranty.

 

[sorka]

Really interesting data from Sorka. I have a 2016, with a max of 40 amp on one inverter. I charge at 30 most of the time to put less strain (and heat) on the inverter. I understand they go and I plan on keeping my car for 5-6 years. I did not buy the extended warranty.

That is the best reason to charge slow. The on board charger is not covered by the 8 year infinite mileage warranty while the battery is.

 

[aerodyne]

Interesting tidbit for those that are charging slower...

Did you notice the rating on Gen 2 mobile connector adapter? It says 30A, not 32A. Called Tesla Support and they said it was good for 32A, "But the regulators made them label it 30A"

Not the most satisfying answer.

To preserve my single charger and Gen 2, and keep the cables a little cooler, I charge at 27A....10% safety factor, and gives me an even 20 miles of range per hour.

 

[sorka]

When I'm at work charging, the 208v 40 amp plug I can use is limited to 3 hour time slots, so I charge at 40 amps every single time because I have to.

At home, I start at 11 pm (offpeak) and set the charge as slow as I can get away with to finish by 7 am which means changing it all the time since I never start at the same SOC.

 

[SSedan]

That is the best reason to charge slow. The on board charger is not covered by the 8 year infinite mileage warranty while the battery is.

So the point about the charger not being covered is reasonable but the statement. "while the battery is not" would seem to suggest 40amps is hard on the battery and I think we have made a solid point that it is not. Taking 8+ hours to charge a battery from dead to full is not in any way hard on it especially not when equipped with cooling which will balance temp even if cooling isn't necessary.

 

[sorka]

So the point about the charger not being covered is reasonable but the statement. "while the battery is not" would seem to suggest 40amps is hard on the battery and I think we have made a solid point that it is not. Taking 8+ hours to charge a battery from dead to full is not in any way hard on it especially not when equipped with cooling which will balance temp even if cooling isn't necessary.

My statement had nothing to do with the battery. My point is that 40 amps is hard on the on board charger which is not covered by the 8 year infinite mile warranty.

 

[Shoobydoodoo]

When charging at the same voltage, there's very little difference in charging efficiency. If anything, it's a little less efficient at 80 amps because the pumps and fans are sometimes going:

View attachment 396170

I have hundreds of charging sessions logged from 20 amps to 80 amps and unless the cooling system turns on, it's always right around 90%.

Some might confuse longer charging with efficiency since that's often associated with lower voltage. Charging at 110v *IS* way less efficient because the inverter's overhead to step it up to 400v is far higher than stepping up from 245 volts.

View attachment 396176

Over 50+ charging sessions at work on 110v, my average efficiency is about 71%.

Is this data from TeslaFi?

 

[jerry33]

When I'm at work charging, the 208v 40 amp plug I can use is limited to 3 hour time slots, so I charge at 40 amps every single time because I have to.

At home, I start at 11 pm (offpeak) and set the charge as slow as I can get away with to finish by 7 am which means changing it all the time since I never start at the same SOC.

208 V @ 40 amps is not going to be hard on the onboard charger, wall connector, or mobile connector. Residential standard is 240 V. So charging at 208 V @ 40 amps is 87% of normal 40 amp residental charging.

 

[sorka]

208 V @ 40 amps is not going to be hard on the onboard charger, wall connector, or mobile connector. Residential standard is 240 V. So charging at 208 V @ 40 amps is 87% of normal 40 amp residental charging.

The onboard charger has to work a little bit harder to step the voltage up to 400+. Also, the main thing that determines how much stress the charger is under is current, not volts. Higher volts and lower amps is easier than lower volts and higher amps.

 

[sorka]

Is this data from TeslaFi?

Yes.

 

[Barry]

208 V @ 40 amps is not going to be hard on the onboard charger, wall connector, or mobile connector. Residential standard is 240 V. So charging at 208 V @ 40 amps is 87% of normal 40 amp residental charging.

It's the current that generates the heat - I squared R.

 

[Silicon Desert]

Really interesting data from Sorka. I have a 2016, with a max of 40 amp on one inverter.

Well, if you are talking about the energy transfer unit ("Charger") in the car, then technically speaking it is not an inverter. It is more like a full-wave rectifier (in electronic terms). An inverter only converts DC to AC.

 

[Rocky_H]

Well, if you are talking about the energy transfer unit ("Charger") in the car, then technically speaking it is not an inverter. It is more like a full-wave rectifier (in electronic terms). An inverter only converts DC to AC.

Thank you--that one kind of bugs me. I frequently see some of the same people who hassle folks for saying "charger" as the external equipment, then refer to the thing in the car incorrectly as an "inverter".