Swapping out a Tidalforce hub battery

The Tidalforce M-750X bike I picked up had a supposedly weak front hub battery. I swapped the front hub with my red S-750X front hub just so it would have a known good battery. I then took the supposedly weak battery and replaced it with the other known good front hub battery I have. I opened up both and took a couple of pictures of the two packs as well as close ups of the suspect pack from the silver M-750X.

The bad battery was supposedly replaced with a reconditioned one and from the looks of it, wasn't soldered particularly well. There are lots of uneven solder joints and lots of bubbles in the solder. Typically this is caused by an inadequate soldering iron (not enough wattage) or bad soldering technique. I prefer smooth, even, shiny and bubble free solder joints.

Side by side (good on the left, bad on the right)

Good battery with center axle nut and wheel bearing mounted

bad battery without center axle nut or wheel bearing

Solder joint on bad battery

Solder joint on bad battery

Solder joint on bad battery

Solder joint on bad battery

Solder joint on bad battery

Solder joint on bad battery

After swapping out the center axle rod and nut, it was pretty smooth sailing.