When charging at home is the rate of charge constant?

[lencap]

Greetings!

I couldn’t find an answer to this question when I searched. If it’s available and I missed it, I apologize.

When I plug my 2023 Tesla AWD Y into my home charger at 32amps it provides 30 miles of range per hour. Does it continue to charge at that same rate until it reaches my targeted battery percentage, or does it taper and charge more slowly as the battery fills, as it does while on a SuperCharger?

I’m trying to determine the optimal charging time/utility rate at home, and knowing if there is a linear or tapered charging cycle is helpful information to minimize charging time/costs.

Thanks for the help.

 

[E90alex]

It’s constant unless the EVSE gets overheated or detects some problem and starts ramping down the amperage.

 

[StanMI]

I don't think there is any taper until you start getting close to 100%.

If I'm wrong, others will post.

 

[jcanoe]

I have never observed any tapering while charging my 2020 LRMY using Level 2 charging. My 2017 Chevrolet Volt would taper the charging amperage just before charging had been completed. The only time the Tesla Mobile Connector or Tesla Wall Connector will lower the charging amperage is if this equipment detects a problem such as a power plug that has become too warm or a voltage sag.

 

[Sophias_dad]

Tapering definitely occurs but only very close to 100%, certainly 95% or more.

 

[lencap]

Thank you for the replies - they are very helpful.

 

[Rocky_H]

@lencap Well, the answer is both yes and no. The tapering curve is always there, but you will almost never see it when charging at home. It would hypothetically be lowering the charging power from 70, 60, 50, 40, 30, etc. kW, but your home charging is so low power, like 10kW, so it wouldn't have to be limited until you are probably over 95%.

 

[exxxviii]

When I plug my 2023 Tesla AWD Y into my home charger at 32amps it provides 30 miles of range per hour. Does it continue to charge at that same rate until it reaches my targeted battery percentage, or does it taper and charge more slowly as the battery fills, as it does while on a SuperCharger?

Ditto some of the above... I have a 48A rate. Mine charges at 11.5 kW until I get into the 90% range, and then it slows way down, like into the low single digits in the last few steps to 100%.

 

[lencap]

A small taper at the end of the cycle won't affect me much at all. The key is to be sure I can get the constant 30 mile MPH charge rate. My capacity is only 279 miles, so 8 hours would almost always be enough time to manage the best utility rates.

I'm also impressed with the Y's efficiency compared to my 2018 M3. The weather conditions are nearly ideal today - 73 degrees, little wind. HVAC turned off. I've averaged almost 4.5 miles/KWh today, and in the 8 days I've owned the car, in mostly cooler temps than today, the overall efficiency is just about 4 miles/KWh, mostly on local streets with normal stop/go traffic for a mid sized city.

Thanks again!

 

[archae86]

I have a model 3 RWD, with the "iron" battery. So I'm supposed to charge to a full 100% weekly. Even though I use a 27 A maximum charge rate (down from the 32 maximum available for this model) when charging with my Wall Connector it slows down right near the very end. As I normally charge our model 3 LR to 80% I don't see any taper at all, even thought I've got that one charging at 40A.

 

[E90alex]

I have a model 3 RWD, with the "iron" battery. So I'm supposed to charge to a full 100% weekly. Even though I use a 27 A maximum charge rate (down from the 32 maximum available for this model) when charging with my Wall Connector it slows down right near the very end. As I normally charge our model 3 LR to 80% I don't see any taper at all, even thought I've got that one charging at 40A.

100% charge will always be slow at the end as the BMS is trying to calibrate and balance the pack.

 

[TomServo]

For most of the time I get a rock solid 11 kWH from my Gen 3 HPWC, but if the voltage should drop I have seen it drop to 10. At my residence I usually get between 232 and 240v but every once in a while I’ll see it drop to below 230 for a few minutes, that’s when I see the kWH drop. I assume this is common and not something I should be alarmed about In a new home and subdivision.

 

[davewill]

For most of the time I get a rock solid 11 kWH from my Gen 3 HPWC, but if the voltage should drop I have seen it drop to 10. At my residence I usually get between 232 and 240v but every once in a while I’ll see it drop to below 230 for a few minutes, that’s when I see the kWH drop. I assume this is common and not something I should be alarmed about In a new home and subdivision.

The number that the Tesla shows on the screen is rounded to the nearest kW. Since watts are volts times amps, a slight dip in the voltage can cause that kW number to suddenly flip one digit lower. I think that's all you're seeing.

Finally, a quick thing on units. Charge rates are kW. The amount of energy your battery holds, or the unit your utility bills for, are kWh.

 

[fhteagle]

I have observed (via amps/watts telemetry on my OpenEVSE, recorded by HomeAssistant / Influxdb)

- Taper begins more than a half hour before charge to 100% completes:

- Taper in the last few minutes of a charge that targets less than 100%

- Amps reduction when the supply dropped below 220V, due to other electrical equipment in the house failing.

Vehicle is 2023 MYLR

 

[TomServo]

Not in my experience. Just watch the available incoming VOLTS when charging. I see fluctuations as much as 14 VOLTS depending on time of day and other appliances using electricity while charging with my Gen 3 HPWC pulling 48 amps.