Welding outside terminal ring on LFP prismatic cells due to low penetration—acceptable or risky?

[zee123king]

I am assembling 12.8V 135Ah and 12.8V 150Ah LFP battery packs and using 35 mm × 3 mm aluminum busbars. For welding, I have access to a 3 kW automatic laser welding machine, which limits penetration capability for thicker busbars.

Initially, I performed laser welding directly over the marked circular zone on the cell terminal at full power. However, the weld strength was insufficient—the busbar could be loosened easily, indicating poor fusion.

To address this, I modified the welding approach by:

• Increasing the weld circumference
• Shifting the weld points outside the marked circular region

With this revised configuration, the weld appears significantly stronger. I also performed a basic mechanical check using a screwdriver to pry the joint, and the bond held firm (image attached for reference).

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My question​

Given that the welds are now placed outside the marked circular zone on the terminal:

• Is this bond electrically and mechanically acceptable for long-term use?
• Is welding outside the marked ring a valid practice, considering the limitation of laser power and busbar thickness?