Tesla Model 3 Tesla Model Y Tesla Model S Tesla Model X Battery & Low-Voltage Professional repair only

Tesla BMS_a079: Charging Limited to 50% - Cost & Fix

By the EV Fix Guide editorial team · Updated October 24, 2026 · How we estimate costs

Quick answer

BMS_a079 means the car has detected a problem inside the high-voltage battery and caps charging at 50%. The car is still OK to drive, but range is roughly halved and Tesla's usual fix is a pack repair or replacement, often covered by the battery warranty. At a Tesla Service Center this typically costs $0 (Under battery warranty) / $12,000 - $20,000 (New or remanufactured pack, out of warranty). An independent shop charges about $2,500 - $7,000 (Module-level pack repair, where available) — potential savings of 50% - 80% (out of warranty). Do not attempt this at home.

BMS_a079: Unable to Charge - Maximum Charge Level Limited to 50%

Symptoms

'Unable to charge - Maximum charge level reached' or 'Reduced maximum charge level - Schedule service' alert
Charging stops at about 50% state of charge, or will not start if the battery is already above 50%
Range roughly halved compared with normal
Often reported without any earlier warning signs

Repair cost: Tesla vs independent shop vs DIY

Option	Typical cost (USD)
Tesla Service Center	$0 (Under battery warranty) / $12,000 - $20,000 (New or remanufactured pack, out of warranty)
Independent shop	$2,500 - $7,000 (Module-level pack repair, where available)
DIY	Not possible at home (High-voltage hazard)
Potential savings	50% - 80% (out of warranty)

Ranges are US estimates compiled from owner reports and shop quotes; prices vary by region, model year and parts availability. Report your price.

Can an independent shop fix it?

If your car is still inside Tesla's 8-year battery warranty, go to Tesla first; a pack fault like this is normally a warranty repair. Out of warranty, a few independent EV battery specialists can diagnose the faulty module and repair the pack for much less than a new one, but this is lab work on a high-voltage pack, not a regular garage job.

Get matched with an independent shop →

How professionals repair it

Safety warning: The fault is inside the high-voltage battery pack (several hundred volts). There is nothing safe for an owner to repair. What you can do is document the alert, check warranty status and get quotes.

Tools a shop uses

Tesla app and screenshots of the alert (for warranty claims)
Your purchase date and odometer reading (to check warranty coverage)

Steps

Keep driving normally; Tesla says the car is OK to drive. Plan trips around roughly half your normal range.
Screenshot the alert and note the date, mileage and state of charge where charging stops.
Check your battery warranty: 8 years, with a mileage limit that depends on model and year (typically 100,000 to 150,000 miles / 160,000 to 240,000 km).
Book service in the Tesla app and describe the alert code exactly. Ask whether the repair is covered and whether the replacement pack is new or remanufactured.
If you are out of warranty, ask an independent EV battery specialist for a diagnosis and a module-repair quote before accepting a full-pack replacement.

Pro tip: BMS_a079 has drawn regulator attention in South Korea after many owners reported it. Keep records of every service visit; if the fault comes back after a repair, your paperwork makes a second warranty claim much easier.

Had this fixed? Share what you paid

Owner-reported prices keep these ranges honest. We publish only anonymous averages and email you the results.

Frequently asked questions

How much does it cost to fix a BMS_a079 battery alert on a Tesla?

Tesla Service Center: $0 (Under battery warranty) / $12,000 - $20,000 (New or remanufactured pack, out of warranty). Independent shop: $2,500 - $7,000 (Module-level pack repair, where available). DIY: Not possible at home (High-voltage hazard). Typical savings versus the service center: 50% - 80% (out of warranty).

Can I fix a BMS_a079 battery alert myself?

No, this is not a safe DIY job. The fault is inside the high-voltage battery pack (several hundred volts). There is nothing safe for an owner to repair. What you can do is document the alert, check warranty status and get quotes.

Can an independent shop fix a BMS_a079 battery alert instead of Tesla?

Which Tesla models are affected by a BMS_a079 battery alert?

This issue is reported on the Tesla Model 3, Model Y, Model S and Model X.

Tesla Model 3 fixes & recalls, by email

One email a month. New fixes, recalls, real prices. Free.

Related guides

This guide is for information only. High-voltage components (orange cables) can be lethal — leave them to trained technicians. Not affiliated with Tesla, Inc.