Vacuum Molded Battery Box
Vacuum Molded Battery Box from Timothy Halsch
Vacuum Molded Battery Box

The Electric Vehicle Team I am a member of at Rochester Institute of Technology built electric bicycles to get members around campus. The original battery and controller compartment was a flimsy bag that wouldn't keep the items secure. Since this represented our team and we all take pride in our work, we wanted to make a quality looking part.

This started with brainstorming and designing, first starting on a white board and later moving to Solidworks for final design. I helped lead the design phase since I had a more comprehensive background in manufacturing compared to some of the younger members. I was able to guide the design as to what would and would not be possible (such as incorporating draft for vacuum molding and sharp corners causing stress concentrations).

I was the most comfortable with woodworking so I made the mold for the end caps and body out of MDF. Another team member and I were responsible for the vacuum molding of the end caps, which I later milled and drilled.

MDF box to mold the body of the part.
Cardboard mock up to insure fit of batteries and controller.
Thermoforming the ABS on a strip heater to form the body of the part.
Slot in front directs air over the controller's heat sink, keeping it cool. A fine mesh will later be added to keep foreign objects out and make it harder for water to get in if caught in the rain. The wires come out through the hole in the bottom within a rubber grommet to keep from chaffing and eventually shorting of the wires.
The rear is removable to provide access for charging the batteries. The box is designed to hold between one to four batteries (either 36 or 48 volt) to provide expandibilty for the future and have the flexibility of being able to use this mold for other bikes with different set ups. Foam blocks have been constructed to take up the empty space yet keep open air flow for the controller. These prevent the batteries from moving while in use.
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Vacuum Molded Battery Box

The Electric Vehicle Team I am a member of at Rochester Institute of Technology built electric bicycles to get members around campus. The original battery and controller compartment was a flimsy bag that wouldn't keep the items secure. Since this represented our team and we all take pride in our work, we wanted to make a quality looking part.

This started with brainstorming and designing, first starting on a white board and later moving to Solidworks for final design. I helped lead the design phase since I had a more comprehensive background in manufacturing compared to some of the younger members. I was able to guide the design as to what would and would not be possible (such as incorporating draft for vacuum molding and sharp corners causing stress concentrations).

I was the most comfortable with woodworking so I made the mold for the end caps and body out of MDF. Another team member and I were responsible for the vacuum molding of the end caps, which I later milled and drilled.

Timothy Halsch
Mechanical Engineering Technology student at Rochester Institute of Technology Rochester, NY