Welcome to the Facebook Tesla BMS_u029/BMS_u018 Group (Group) FAQ

Compiled from research on the internet, Tesla Motors Club and the FB Tesla BMS_u029/18 Group

Original Author:Ray Johnson Taken Over/Continued by Chris (KmanAuto) islanbdbayy@yahoo.com (last edited 19 Mar 2024)

What is BMS? BMS stands for Battery Management System. Tesla Model S Battery System and

Battery Management System (BMS) for Electric Vehicles

What is BMS_u029/18 (029/18)? 029/18 is a non-specific Tesla alert that is usually accompanied by “Maximum battery charge level reduced. OK to drive. Schedule service”. In most cases your range is limited to around 60 miles. Or worse, you may completely be unable to drive.

What triggers 029/18? Based on Group feedback - just happened one morning, after OTA update, after Factory Reset, after MCU2 upgrade, after Supercharging or bad luck.

Which Teslas are affected? Currently primarily limited to 2012-2015 Model S/X’s. We are yet to hear of any 2016's being affected as they come off warranty and owners are having to pay for repairs. Neither mileage nor types of charging habits seem to be immune.

What exactly do the alerts mean? BMS_u029 = pathological reduction in brick capacity, BMS_u018 = state of charge imbalance What's it all mean?and Tale of Two Errors and Video - Tesla Error codes and what they mean BMS-U029, BMS-U018, BMS-W164 and BMS_u029 - What Exactly Is Going On?

What’s wrong with my High Voltage battery pack? The 029/18 alert is there for a reason. Only further diagnosis by Tesla or a 3rd party vendor will determine the exact issue(s) with your battery pack. For example battery imbalance, reduction in brick capacity, hardware failure, water ingress, etc. Here’s DIY diagnostics Matt's DIY Diagnostics Also Recell Diagnostics is offered at no cost. In some cases apps like Scan My Tesla will help but one needs to know how to interpret the readings. ScanMyTesla & TM-SPY

What are my options if I’m in need of a replacement pack and I’m out of warranty? Your repair decision will likely depend on both personal finances and what you want to do with the car in the long run. When selecting options, buyer beware and get testimonials. There are pros and cons to each option listed below. After determining the root cause(s) of the 029/18 alert, the following are some options.

• New or remanufactured replacement pack from a Tesla Service Center - new $21k ish USD, reman $16k ish. Both come with a 4 yr/50k mile warranty. New gives you the original 265-270 mile EPA rated range on an 85 kWh pack. Reman gives you around 240 miles rated range.

• Remanufactured replacement pack from a 3rd party - $10k for 240 mile rated range, warranty about $1250/year extra.

• Replacement pack from auto parts salvage yard - $10k for 240 mile rated range. In some cases, salvage yard may recommend installers. DIY swap project here DIY salvage yard replacement pack and More DIY

• Repair of your existing pack at the cell, brick or module level by a 3rd party - $7k-$10k. Extra warranty cost either not offered or about $1250/year extra.

• Sell your car at a loss with 029/18 alert known to buyer - currently $7K-$10K.

• If you’re comfortable around high voltage and have the tools/time/know how, remove the pack and attempt to fix yourself. Cost is your time, learning curve tolerance, and any material costs. And depends on what needs repair. CAUTION - these packs are lethal if not managed safely.

• Live with the limited range - some conjecture that living with limited range is temporary Limited Range

• 029 Reset device discussion and More BMS reset device discussion and Video - reset device owner review

• Firmware roll back discussion

Are there any recommended repair shops ? When selecting either Tesla or 3rd party vendors, buyers beware and get testimonials. The following are some repair shops recommended by members of the Group (in alphabetical order):