Were Code 36 MXR Warranty Replacement Batteries Still Susceptible to the same Wirebond Failure?

[jaylude]

Hey all, first post here. Had a specific question I couldn't find an answer on. I'm plenty familiar with the Code 36 / wirebond issue based on readings here (thanks contributors!) and my past familiarity with Li-ion cells, building battery packs and whatnot. But for the cases where a Code 36 MXR battery had the entire module replaced under warranty, were the replacement modules also still susceptible to the issue? Or did Alta change the wirebond process / QA checks by the time the issue was recognized, rendering any warranty-replacement packs not susceptible?

Thanks,
Jay

 

[Mark911]

In my opinion, regardless of whether they changed the process or not, wire bonds to a cells shoulder are inherently more susceptible to breaking under stress than otherwise. Therefore, although reliability may be improved it’s still going to be prone to failure over time. My opinion.

 

[jaylude]

Mark - I'm in total and complete agreement, no doubt. Give me a typical spot welded nickel fuse strip to the caps over the aluminum wire / wirebond any day.

Nonetheless, my hope was to hear something may have changed process wise or QA wise, and that someone here might have something definitive as far as warranty replacements vs OEM installs.

 

[Rashid510]

Mark - I'm in total and complete agreement, no doubt. Give me a typical spot welded nickel fuse strip to the caps over the aluminum wire / wirebond any day.

Nonetheless, my hope was to hear something may have changed process wise or QA wise, and that someone here might have something definitive as far as warranty replacements vs OEM installs.

Strongly disagree. The EV industry has been moving towards wirebonding. The backyard module community does spot welding due to costs. But the risk is higher with having issues with packs of that manufacturing design. The Alta wire bonds are stitch welds which are more "reliable". But unfortunately theres only so much DOE that can be done before pulling the trigger on production.

 

[DonCox]

I agree with @Mark911 on the fact that the Wirebond will fail when a cell fails regardless of manufacturing flaws. It is the indicator that a cell has shorted, or gone bad.
My first lithium pack I built were 16 LiFePo4 Prismatic 40AH cells. If one failed, the pack would still work, at a lower voltage, since the bad cell appeared as a short or buss bar. But when you have parallel packs 2P or 20P, if a cell dies, it is a short to the other cells in that group, which could be dangerous. Here is an article I found on the web concerning Wirebonding written about Tesla's method

Beyond the simple connections, Tesla describes a design method that also uses aluminum wire connections as fusible links that allow the expected current to pass, while breaking the connection in an overcurrent condition like a short circuit. Tesla’s engineers believe that another problem with other bonding methods is a lack of electrical protection – without a fuse, a single cell can internally short due to a malfunction or damage, and render unusable all of the other cells to which it is connected in parallel.

 

[Warren]

In my opinion, regardless of whether they changed the process or not, wire bonds to a cells shoulder are inherently more susceptible to breaking under stress than otherwise. Therefore, although reliability may be improved it’s still going to be prone to failure over time. My opinion.

I think your correct Mark as my 2018 Mxr got a code 36 at 450 miles got pack replaced 2 weeks before thay closed up shop. New pack went 740 mile until one hot August day running it hard code 36 came back. I’ve been riding it ever since with code and got over 1800 miles and 160 hours all Mx riding. Still working and charging ok w/code 36 &36.

 

[privateer703]

So I just noticed my Code 37 is now a Code 37 AND 36. This is a battery that was replaced under warranty. I have all the cables, but I wasn't worried about the Code 37 so I haven't setup MT yet. Now I have a reason to. Bike charges and runs fine, didn't even notice the Code 36 since when I first saw the error it was only reading Code 37. While riding today I noticed it was flashing between Code 37 and Code 36.