Battery Health Notification From BMS

Common Symptoms

• Yellow or amber notification banner appears on the touchscreen
• Touchscreen notifications panel shows a message about battery health or capacity
• No reduction in power or acceleration is noticeable
• Estimated range display may show a slightly lower maximum than when the car was new
• Car charges, drives, and operates normally in all other respects
• Scan My Tesla or TM-Spy logs BMS_w033 with no accompanying fault shutdown codes
• Notification may reappear after being dismissed if the underlying condition persists

Probable Causes (Ranked by Likelihood)

• Normal long-term lithium-ion cell capacity degradation reaching a BMS reporting threshold Very Likely
• Frequent DC fast charging (Supercharger) sessions raising pack temperature history and triggering a charging-habit advisory Likely
• Battery consistently charged to 100% or discharged below 10% repeatedly, prompting a state-of-charge habit notification Likely
• Minor cell-group imbalance detected by BMS during a balancing cycle, logged as informational before it becomes a fault Possible
• Firmware update recalibrating pack capacity estimate, causing BMS to log new baseline and issue notification Possible
• Extended storage at high or low state-of-charge affecting cell chemistry tracking Less Likely
• Single weak cell in a module pulling down the estimated usable capacity just enough to cross the w033 reporting threshold Less Likely

Step-by-Step Diagnostic Procedure

1. Open the touchscreen notifications panel by swiping down from the top of the screen. Read the full text of the BMS_w033 message. Tesla often includes specific guidance in the notification itself, such as adjusting charge limits or scheduling service.

2. Navigate to Controls > Software > Additional Vehicle Information and note your firmware version. If a software update is pending, install it. A firmware update can recalibrate the BMS and clear erroneous notifications.

3. Check your daily charge limit. Go to Charging > Set Limit and confirm it is set to 80-90% for daily use, not 100%. Charging to 100% every day accelerates cell wear and can repeatedly trigger this notification.

4. Connect Scan My Tesla using an OBDLink MX+ or Veepeak adapter. Navigate to the BMS live data screen and review the cell voltage spread. A spread greater than 50-80 mV between the lowest and highest cell groups at rest suggests imbalance that goes beyond a simple informational notice.

5. In Scan My Tesla, check the pack State of Health (SOH) percentage if your adapter firmware exposes it. A value above 80% is generally acceptable. Below 70% on a car under 100,000 miles may warrant a Tesla service appointment to check for premature degradation.

6. Review your Supercharger session history in the Tesla app under Charging. If you DC fast charge daily and the car is your primary vehicle, consider mixing in Level 2 home charging to reduce cumulative pack heat stress.

7. If the notification reappears within a few days after dismissing it and nothing else changes, schedule a service appointment. Bring a screenshot of the notification text and the Scan My Tesla cell voltage log. This gives the technician something concrete to work from without requiring Tesla Toolbox 3 access on your end.

8. If you observe any accompanying codes such as BMS_f series faults, reduced range warnings, or power limiting messages alongside BMS_w033, treat the situation as more serious and contact Tesla Service immediately. BMS_w033 alone is informational but should not be ignored if it arrives in a cluster of other BMS alerts.

Frequently Asked Questions