My wife and I have been hiking up at Mt Charleston weekly to avoid the heat down in the Vegas valley. The climb is 5700' to the trails above. I was not paying much attention to the battery, but my wife noticed last week that the battery % was actually increasing on the drive back down the mountain. That surprised the heck out of me! I knew the regen braking would add some charge back into the battery but never expected that just driving down the mountain would do the same! I am use to driving an ICE car up the mountain and using the brakes most of the way back down. It is so nice to not need to ride the brakes going down the mountain. Anyway, I did a short video yesterday to demonstrate the results of our ride up/down the mountain and to show the battery % change. I was also surprised at the huge demand in power going up the mountain, nearly 3 times the normal wh/mile going up. This is kinda useful to know for anyone planning a trip up a mountain to avoid running the battery down too low or possibly even to 0%.
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Model Y Regen Braking and Charging up/down a Mountain
- Thread starter Curious Nomad
- Start date
Quick Question: During the above video the Model Y made a beeping noise twice on the way down the mountain. You can hear this at 4:10 in the video. It sounds similar to heavy equipment when backing up. Both times this occured it stopped after around 20 seconds. It has not done it since and no alarms were shown on the screen. Does anyone know what this beeping is or what it means? Thanks for any advise.
Yep... 4000Lbs is a heavy load to bring up hills, physics indicate it takes a lot of energy. Same for an ICE car, you probably just never checked it. Physics also indicate there's a lot of potential energy in that 4000lbs mass that's up the mountain, just waiting to go down. Regen can capture 70-80% of that energy as you go down, unless something heats up and regen must be limited somehow.
TomServo
Active Member
ChadS
Last tank of gas: March 2009
Here's a picture of my wife's Model S on Pike's Peak in 2014:
There is (or at least was) a checkpoint on the way down where they check the temperature of your brakes. The guy checking was astounded at how cool the S's brakes were - he wasn't familiar with regen.
A decade ago owners of the Model S (with weight pretty similar to a Model Y) figured it would lose 10 miles for every 1,000 feet of elevation gain (for example, see THIS thread, in the "Elevation" section). That number is fairly well-fixed unless you are carrying a lot of weight, but the amount you get on regen is more variable as it depends on speed coming down, braking, amount lost to wind, etc. But usually you can get back around 2/3 of what you lost going up.
HERE is another thread with numbers on elevation gain for a Model 3.
And HERE is another Model S thread, this one on Haleakala.
There is (or at least was) a checkpoint on the way down where they check the temperature of your brakes. The guy checking was astounded at how cool the S's brakes were - he wasn't familiar with regen.
A decade ago owners of the Model S (with weight pretty similar to a Model Y) figured it would lose 10 miles for every 1,000 feet of elevation gain (for example, see THIS thread, in the "Elevation" section). That number is fairly well-fixed unless you are carrying a lot of weight, but the amount you get on regen is more variable as it depends on speed coming down, braking, amount lost to wind, etc. But usually you can get back around 2/3 of what you lost going up.
HERE is another thread with numbers on elevation gain for a Model 3.
And HERE is another Model S thread, this one on Haleakala.
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Mateo83
Active Member
Good stuff, thanks. My trip up the mountain used around 2% of battery for each 1000' of elevation gain, so 6000' of elevation needed an extra 12% of battery to compensate. Lots of other factors to consider speed and battery % charge, but that is probably the rule of thumb I will use for trips up mountains. I did see another video on YouTube where the driver had over 90% charge on his battery before going down the mountain and got very little regenerative braking. Batteries that are close to full seem to have more resistance to being charged the closer they get to 100%.
Regen is charging, and it can push more than 60kW into the battery. As you charge your battery, say at a supercharger, the rate of charge (kW) lowers to protect the battery. Past 80% SOC I don't think you'll get 60kW while charging. It's possible that the car accepts a regen power of 60+kW over 80% SOC for a short period but after a while it would certainly reduce that power. Higher SOC should see even lower regen.
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