Tesla
Oct 22, 2021

Why Does My Tesla Battery Limit Decline Over Time?

Some owners have found that they will consistently charge to a certain battery limit, say 90%, however over time the range will drop significantly.

Why Does My Tesla Battery Limit Decline Over Time?

As a Tesla owner, are you concerned with the long term longevity of your Tesla battery?  Maybe you, like other Tesla owners, have been following the charging recommendations through the Tesla owner’s manual, only to find that your Tesla battery limit has declined significantly over a short period of time. For example, some owners have found that they will consistently charge to a certain battery limit, say 90%, however over time the range will drop significantly.

If you're active in the Tesla Forums, you’ve definitely seen these user accounts circulate on the forums. One particular Tesla owner purchased a S60 in 2016 and after only driving their Tesla for 8000 mile, consistently charging to 60% resulted in a loss of battery capacity where the driving range dropped from 210 mile range to a 195 mile range. This might not seem like a lot but this is a 7% reduction in range! More here. So, what’s going on?

Tesla’s Battery Algorithm

If you’re consistently driving within a specific range, it may be that your Tesla’s charging algorithm is misrepresenting the true range your Tesla is capable of on a given charge rather than your Tesla battery is actually sustaining a significant loss of capacity. When you constantly charge your Tesla within a specific range, your Tesla’s charging algorithm can actually begin to misrepresent your Tesla’s total range through mis-calibration. Your Tesla’s advanced charging algorithm is projecting a driving range based on analysis of many confounding factors such as charge time, driving time, historical Tesla battery charging data, and battery age to name a few. The challenge here is if you drive within a specific SoC or State of Charge (the lower and upper limit of battery charge), your Tesla’s charging algorithm will slowly mis-calibrate the true range. How to fix this?

Deep Discharge

Luckily for Tesla owners that are experiencing these driving range challenges there is good news. Performing a deep discharge can result in a higher projected driving range effectively calibrating how your Tesla is estimating driving range.  A deep discharge is just what you may think, discharging your Tesla battery to somewhere around 15%, a lower bound charge state than your Tesla algorithm is accustomed to. In performing a deep discharge and then charging your Tesla battery a safe upper limit of 80 - 90%, you’ll allow your Tesla charging algorithm to assess the charging capacity of your battery more effectively.

Here are some examples of Tesla owners reporting a higher range after a deep discharge:

  • One user on the Tesla Forums reported a 2% increase in range after performing a deep discharge.  Here
  • Here’s another example of a Tesla owner who performed a deep drain and recalibrated their range to 300 miles here.

Other Considerations

One thing to keep in mind is to make sure you are not confusing reduced range with phantom draining. Phantom draining occurs when your Tesla is not plugged in and some energy from the battery is used for Tesla services while the car is off. This is when your Tesla periodically uses energy from the battery for system tests and charging the 12V back-up battery when necessary. If you are finding challenges around phantom draining, check out this video from the guys at TeslaLoop who worked through some steps to stop phantom draining here.

Next Steps

To learn more about your Tesla’s battery read our article “The Comprehensive Guide to Maximizing your Tesla’s Battery Efficiency and Battery Life”.  Also, if you’re looking to optimize your cost savings, track exactly how much you spend charging your Tesla, or just want to do your part to minimize the load on your utility grid, then check out the free app Optiwatt.

Tesla Model 3 Battery Calibration

You can calibrate your Tesla 3 battery by driving until you're down to a single-digit percentage range. Then let it sit for one hour while pinging periodically with the app or door handle to keep the car awake. Charge it fully, then do the same thing.

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