The uStart is a simple replacement for a standard lead acid battery but reduces the number of batteries a truck would require through its 15 year life from 30 to 5. For a large fleet this would replace thousands of lead acid batteries saving millions of dollars and would eliminate thousands of tons of lead from the environment.
The module works by monitoring the vehicle's electrical bus, providing and absorbing power when required. Using just batteries can result in a wide range of results depending on load, age, temperature, and current state of charge. As a start is initiated, terminal voltage drops and the battery will discharge. The lower the voltage drops, the more current has to be supplied, further stressing the battery and starter.
In typical delivery operations the battery cannot recover from the previous cycle in the time between stops, resulting in the batteries operating at a low state of charge (SOC) all of the time, and exponentially accelerating the wear of the batteries and increasing the functional resistance (ESR) of the batteries, lowering the voltage further under load.
The current from the ultracapacitor provides rapid, full recharge of the system from the alternator up to 12.5V, giving enough energy for the next stop/start event within 15-30 seconds.
Next: trial results