Here are pictures of an Optibike battery pack that was opened up by an Optibike owner in Thailand. The Optibike owner was getting half the expected capacity out of his 3 year old pack, and sending the pack to the United States was out of the question, so he had the pack dissected and repaired locally where skilled labor is cheap. What he found is interesting and he photographed the results for posterity.
Optibike is using generic 18650 cells to make their packs. The highest quality cells are name brands made by Panasonic or Samsung and cost $10 each to buy (the packs consists of 100 cells).
Optibike is offering a 3 year warranty on their pack, but to get warranty service the entire bike needs to be hazmat shipped to Boulder Colorado at the bike owners expense. Therefore some Optibike owners are resorting to taking apart their Optibike and repairing their own pack by replacing bad cells..
This battery pack was epoxied and welded together in a way that it took hours of painstaking labor to tear and chisel the pack apart to get to the bad cells. This pack was obviously not meant to be repaired.
First the top cover was removed from the pack…an easy task:
Next the paper was peeled back, showing that the Optibike consists of 10 banks of 10 cells for a total of 100 cells (3.7 volts each, so 37 volts) to make up the 26-Ah pack.
Next the aluminum bottom case needed to be removed. Not easy, epoxy was used to bond the 100 cells to the Aluminum case. The case had to be torn apart to access the cells.
Next the metal tabs that are spot welded to each cell needed to be forced off with a chisel. Not easy work:
This is a 30 cell cluster that was broken off from the main pack to get to the two bad cells.
In the bottom of the next picture you can see two lavender cells which are brand new Samsung cells to replace the two duds.
Because the battery pack was torn apart to access these two cells, a new battery case had to be fabricated. Lucky this Optibike is in Thailand, and quality labor like this is very affordable:
Optibike has since changed the company that produces their packs (while still using the same lower quality cells), but now adds a carbon material to insulate each cell which reportedly increases cell life. Optibike calls this technology “cool carbon”.
We suspect it is the US battery manufacturer All Cell which makes the new Optibike pack. Here is an example of how an All Cell pack looks with the carbon insulator. All Cell makes custom packs for OEMs such as Optibike. They also make the battery pack for the Hanebrink and the Picycle.