Costing It Out

A project log for Power Pack: Diversifying the Automobile

Powering the future is about diversifying our energy sources, including the vehicles that power or lives.

james-neeJames Nee 04/21/2016 at 03:340 Comments

In parallel to the enclosure design I wanted to get a sense of how much this project will cost me. The goal is to get a donor vehicle, convert it to electric, and then use that as a test bed for various module types.

Realistically I would not go from 0-60 right away, but would test the components piecemeal - build a scale version of the enclosure to test the design to see where things could improved. Such unknowns like the epoxy bond, the EPDM bulb seal, anchor points for the enclosure, and more need to be tested before a full scale version is built up.

Additionally, the cost of building a full scale prototype is not realistic at first. The current goal is to operate at roughly 375 V, which is similar to what other OEM vehicles operate at (BMW, Nissan, Tesla) meaning their electric motors and inverters are designed for those voltages and should lead to a lower cost price point for power electronics at that voltage range. Unfortunately, not being able to operate at the economies of scale available to OEM manufacturers, building a lithium ion based battery pack to that voltage would cost around $18000 USD before shipping (for a 30 KWHr pack based on Panasonic NCR18650B cells - 28 cells in parallel per group, 100 groups in series). This could be certainly be made more cheaply with used Nissan Leaf cells which could be had for ~ $10000 for a 30 KWHr pack.

Instead it would probably be wiser to go for a lower voltage, and a measly range. 144V is common voltage among motors used by the DIY community, and by virtue of needing less cells in series to achieve that voltage is much cheaper to build.

Finally, I wanted to keep the big picture in mind as well. Though I passionately believe in a pure electric future, I completely expect automobiles to be powered by fossil fuels for a long time yet. Through the budget planning process I began looking into a gasoline powered module, built from readily available single cylinder, four stroke engines. As expected, it is significantly cheaper to run on gas. :(

More on the gasoline module, and the associated super capacitor module, soon!