Home on a hill - regenerative braking

[KlausSimmer]

We live at about 2,500 elevation and my wife works at sea level - so the M3LR is charged (currently limited at around 70%) when she leaves the house - going down the hill she'll get the reduced regen braking alert at some point. Battery is still only at the limited charge amount.

Is there any way to program/set up the charging so the battery can charge beyond the limited charge level with regenerative braking? I.e., if the charge is limited to 70% during plug in, it allows for charging beyond that during driving?

 

[LoudMusic]

Are you certain it's reducing regen due to charge limit and not something else like temperature?

 

[KlausSimmer]

Are you certain it's reducing regen due to charge limit and not something else like temperature?

Not sure but our temps are generally in the 70-80's... In that regard perhaps a better question on my part would be whether or not a given charge limit applies only to plug in?

 

[father_of_6]

I was under the impression that the charge limit refers strictly to plugging in and charging. It would be bizarre to me if regen braking didn't kick in until you're below the charge limit (unless your charge limit is 100%).

I think it's something else. I've read that ideal battery temp is about 104 degrees Fahrenheit... perhaps in the early morning your battery is colder than you think.

 

[father_of_6]

Will regenerative braking go over 'charging limit'?

Hi, We live on a steep hill. So I unplug the car and leave the house. The car has charged to my personal choice of 80%. I only have to leave the garage, coast down and out of the driveway, and I'm on a steep down (15%) for about 1/2 mile. Does regenerative braking pay attention to the...

teslamotorsclub.com

 

[LoudMusic]

Looks like there's two threads on this topic.

limited regenerative charging (not cold, not fully charged)

We have a 2015 Model S. Example of problem. It is 60 degrees outside. The car is only 50% charged. The regenerative charging shows yellow dashes. Even starting at a high speed it charging is limited to only 20-25 wh. Everything I read says the problem is that its cold or fully charged...

teslamotorsclub.com

Will regenerative braking go over 'charging limit'?

Hi, We live on a steep hill. So I unplug the car and leave the house. The car has charged to my personal choice of 80%. I only have to leave the garage, coast down and out of the driveway, and I'm on a steep down (15%) for about 1/2 mile. Does regenerative braking pay attention to the...

teslamotorsclub.com

Second one I actually commented on. Ha ha! My memory is failing me

I'll leave it up to you to scan through those threads for your answers or lack of.

 

[Big Earl]

The charge limit has no effect on regenerative braking.

 

[XPsionic]

Like others said, charge limit doesn't stop the car from regenerating past that limit. What I have found though, is that at 75f, dry weather, just going down a 600' hill can trigger "Regen limited" warnings near the bottom of the hill.

 

[LoudMusic]

That seems weird to me. I drove down Pike's Peak and don't recall getting regen limited. From 14000+ to about 8000 feet. But I was at pretty low state of charge (having just driven UP Pike's Peak).

Regen can produce a lot of electricity. Supercharging at high state of charge gets reduced down below 30kw. The motors can produce way the heck more than that.

 

[Gauss Guzzler]

Yes, the charge limit will affect this, albeit indirectly.

The standard regen setting produces over 80kW of power - on par with a Supercharging station. And just like Supercharging, the battery needs to be low and hot to accept the charge.

Your options are to either find a low enough state of charge to get down the hill without brakes and/or preheat the battery with "scheduled departure" charging. Preheating the battery will cost you in electricity of course, but you'll make much of it back by being able to charge more down the hill and not wearing out your brakes.

 

[Soul Surfer]

Not sure but our temps are generally in the 70-80's... In that regard perhaps a better question on my part would be whether or not a given charge limit applies only to plug in?

True about the temp, but having visited Hawaii, I did find that when going up in the mountains, the temp would drop by as much as 20˚F?

 

[charlieaf92]

I would guess it is related to battery temp - not the charge limit. However I think there is a simple test you can do. Unplug your car in the morning - bump up the charge limit to +10% or so, or just take it all the way to 100 for the purpose of the test, and then do your drive down the hill.

Somewhat related, and interesting, my brother has a one wheel, which has regenerative braking built into it. I don't believe there is a user setting for charge limit, but there is a 'hill' setting for people that start their day at the top of a hill. It limits the charge so that you have available capacity for the regen on the way down the hill. Unlike the Tesla, the one wheel relies 100% on the regen capability for braking, so in this case it is much more important that it is available.

 

[jrweiss98020]

Try turning on the climate ~10 minutes before she leaves the house. Newest firmware is supposed to improve preconditioning as well.

 

[iwannam3]

Set navigation to the nearest supercharger, it will precondition the battery for charging.

 

[RayK]

Set navigation to the nearest supercharger, it will precondition the battery for charging.

I don't know who you are actually responding to, but the OP is reportedly on Maui. As far as I can tell, there are no Superchargers on that island at the moment. The closest ones are on O'ahu, two islands to the West.

 

[LoudMusic]

I don't know who you are actually responding to, but the OP is reportedly on Maui. As far as I can tell, there are no Superchargers on that island at the moment. The closest ones are on O'ahu, two islands to the West.

From Arkansas I just selected Aiea, HI supercharger in the car and the car tried to navigate there for a moment and then just exited the navigation sequence and returned to showing my location on the map.

So yeah, if you live somewhere that has no roads to the supercharger, this probably won't work

 

[RayK]

From Arkansas I just selected Aiea, HI supercharger in the car and the car tried to navigate there for a moment and then just exited the navigation sequence and returned to showing my location on the map.

So yeah, if you live somewhere that has no roads to the supercharger, this probably won't work

Maybe your car's navigation has been set to avoid toll roads and ferries?

 

[KlausSimmer]

Thanks so much for all the replies and info - you guys are awesome - no superchargers on Maui and considering the limited distances here it wouldn't make much sense. And yes, at 2,500 el temps are some 7-8 deg cooler than at sealevel...

Knowing more now about the battery temp issues and the reduction in charging speed/capacity as you approach 100 %, I'm guessing the combination thereof is the issue - especially since I have not seen regen limited at lower battery levels... all this assuming that regen will charge over and above the set limit - has anyone seen information from tesla directly to that effect?

 

[RayK]

<snip>... all this assuming that regen will charge over and above the set limit - has anyone seen information from tesla directly to that effect?

Should be easy enough for you to verify yourself. Before leaving home (high elevation) with much less than a full charge (~80-85%), move the charge limit down to 50% and then watch the regen / power used display as you coast in sections going downhill. Green bar indicating regen should be readily visible.