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Sunday, December 23, 2012

Selecting the Battery Pack

Selecting the battery pack is dependent on my performance targets and the available space within the front frame triangle for the battery case.  I've used corrugated plastic, "coroplast", in the past for various automotive projects and it holds up surprisingly well to outdoor use.  I decided to construct the battery case out of corrugated plastic as it is:

  • stiff
  • light weight
  • tough
  • low cost
  • non-conductive.

Modeling the space available using the free Google Sketchup 3-D modeling tool, it is clear that the standard battery packs offered by Electric Rider do not fit within the bike frame.  Two 48V pack configurations and one 72V pack configuration are modeled and as you can see all resulted in interference with the bike frame:

I constructed the main spine of the bicycle case to obtain real world dimensions and sent the following dimensioned drawing to Electric Rider so they could design a custom triangular battery pack.  After looking at the drawing, Electric Rider advised me as to the largest sized 48V and 72V packs that could actually fit within the available frame space.

Electric Rider came back with two options both somewhat smaller than the packs I had previously modeled. The two packs that could fit within the frame were:
  • A 48V pack with 18.5Ah of battery capacity or
  • A 72V pack with 11Ah of battery capacity (not recommended since batteries would be operating close to their max current output)
Modeling the 48V 18.5Ah back performance to estimate range and top speed results in acceptable performance based on my design targets:

Flat Ground 48V, 18.5Ah Pack

3% Grade 48V, 18.5Ah Pack
As such, I have ordered the Crystalyte Phoenix II Kit from Electric Rider with a custom, triangular 48V, 18.5Ah pack.

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