Full Regen at 90%?

[Rootbeard7]

I got my car in December so the weather has been colder than the norm since then. I usually charge to 90% and don’t get much regen until I’ve driven the car to about 80%.

However, now that it’s been warmer out (70s/80s) I figured it’d be a good test when I took it out this afternoon. However, still no full regen.

So here’s the question: is it possible to get full regen at 90%?

 

[gaM3changer]

Yes, my daily charge is 90% and I get full regen. I'm in socal, car is garaged and I time my charges to complete within 30 of my departure for work to ensure a warm battery.

What is the temp when you first start driving? Do you park outside? When do you charge? Your battery might be cold soaked from the overnight temps, even if it's hitting 70-80° during the day.

 

[Rootbeard7]

Yes, my daily charge is 90% and I get full regen. I'm in socal, car is garaged and I time my charges to complete within 30 of my departure for work to ensure a warm battery.

What is the temp when you first start driving? Do you park outside? When do you charge? Your battery might be cold soaked from the overnight temps, even if it's hitting 70-80° during the day.

When I first started driving today it was around 75-80 degrees. I do park outside. I last charged yesterday around noon. I leave the car plugged in when it’s not in use, but if it got down to 50-60 degrees overnight it’s possible the battery was cold soaked. I just figured by the time I finally drove it this afternoon that would no longer have been an issue.

Around what temperature can I expect to get full regen without having to worry about timing my charges to warm up the battery?

 

[gaM3changer]

I'm not sure about the temp, but the battery has optimal performance around room temp (~70°F). The battery is around 1000 lbs so it has a lot of thermal mass and will take time to warm up.

I've had my car since Nov and have only experienced limited regen a few times due to a cold soaked battery. During these instances, I either turned up the heat and/or did a few hard accelerations and was able to restore full regen fairly quickly.

The 2 methods above wastes energy to heat the battery, but timing the charging cycle seems more efficient as the process of charging heats up the battery anyways.

Also, timing my charges just worked itself out as my cheapest electricity rate is overnight. No extra work is needed, I just set it to start charging 3 hours before my departure time. I don't know when your best rates are, but maybe try charging it in the early morning and have it finish by sunrise. That way, the battery will heat up during charging and can continue to warm as the day progresses.

 

[Rocky_H]

So here’s the question: is it possible to get full regen at 90%?

Generally not--it's still going to be a little bit limited. More on that in a second.

Yes, my daily charge is 90% and I get full regen.

It's probably not showing the dotted indicators on the display, but almost certainly is still somewhat limited because...

The tapering curve of charging slowing down as the battery gets more full is something people are familiar with at Superchargers, but it applies in ALL situations. Regen charging power has a maximum of about 60kW. There is no way you would still be getting 60kW at a Supercharger when your battery was up to 90% full. It's no different with charging power coming from the regen system. So it's probably partially limited down to 30 or 40kW, but they don't seem to show the limitation all the time on the display if it's just a little bit limited like that.

 

[Zoomit]

The tapering curve of charging slowing down as the battery gets more full is something people are familiar with at Superchargers, but it applies in ALL situations. Regen charging power has a maximum of about 60kW. There is no way you would still be getting 60kW at a Supercharger when your battery was up to 90% full. It's no different with charging power coming from the regen system. So it's probably partially limited down to 30 or 40kW, but they don't seem to show the limitation all the time on the display if it's just a little bit limited like that.

Supercharging is a constant power, whereas regen is a limited duration. This allows different power levels for each. Case in point: the Bolt EV will do 70kW of regen at over 90% SOC. It's peak DCFC power is 55kW at about 55% SOC.

I wouldn't be surprised if the Model 3 can do 70kW regen at 90%, where it's optimal Supercharging taper is about 30kW.

 

[Rocky_H]

Supercharging is a constant power, whereas regen is a limited duration. This allows different power levels for each. Case in point: the Bolt EV will do 70kW of regen at over 90% SOC. It's peak DCFC power is 55kW at about 55% SOC.

I wouldn't be surprised if the Model 3 can do 70kW regen at 90%, where it's optimal Supercharging taper is about 30kW.

OK, that really does make sense, and I guess I'll stand corrected. Yeah, the continuous flow up to that point from a Supercharger would mean everything is hotter, so it would need to keep it toned down.

 

[Rootbeard7]

OK, that really does make sense, and I guess I'll stand corrected. Yeah, the continuous flow up to that point from a Supercharger would mean everything is hotter, so it would need to keep it toned down.

So are we back to full regen at 90% being a possibility?

 

[Zoomit]

OK, that really does make sense, and I guess I'll stand corrected. Yeah, the continuous flow up to that point from a Supercharger would mean everything is hotter, so it would need to keep it toned down.

Well, since you mentioned it...Supercharging taper is not due to battery heating. In fact, the battery warms up much more during the high power, lower SOC phase of the charge cycle. As an example, you can plug in a cold battery at high SOC and it will still charge slowly. The charging is limited at high SOC due to the limited voltage that can be applied to the battery. As it charges up, the battery voltage and charger voltage converge, which means lower amperage is used which in turn means lower power.

 

[Zoomit]

So are we back to full regen at 90% being a possibility?

Yes, as @gaM3changer claimed.

 

[abasile]

So are we back to full regen at 90% being a possibility?

With a warm battery and for short periods of time, yes.

However, if regenning down a big mountain as we do regularly, you won't get anywhere near full regen all the way down if you start at close to 90%, even with a warm battery. We normally start down with closer to 80%, and although regen still gets limited, we're able to make it all the way down without touching the brakes if we're careful.