Bricklin EV-1 Owner's Manual
Amps continuously. For short bursts they are capable of 1280 Amps (8C) for 5 seconds, 800 Amps
(5C) for 15 seconds and 800 Amps (5C) for 60 seconds. They have a life cycle of 2,000 at 80%
Depth of Discharge (DOD). Lower DOD will extend the life of these batteries, while 100% DOD will
shorten their life to approximately 1,000 cycles.
Battery Management System
To ensure that the expensive battery pack is properly balanced and protected, a Battery Management
System or BMS has been installed. It is critical for safety and performance that the cells be well
balanced both on charge and discharge. Every cell in the battery pack may not need the exact same
amount of energy restored when a battery pack is charged. Similarly, when cells are discharged,
some cells may be depleted quicker than others.
These conditions may be due to slight variances in the manufacturing process, or by the
interconnects within the battery pack – such as loose or corroded connections. Even subtle
differences, such as the placement of the cells can affect the performance of a cell due to
temperature. Batteries surrounded by other cells will heat up quicker and stay warm longer, while
cells on the end of the pack will generally cool quicker. Though the differences are relatively small,
over time, they can have a cumulative effect on the overall condition of the battery pack or individual
cells.
The BMS helps ensure that no cell in the pack is over charged and also that no cell falls below a
predetermined low Depth Of Discharge (DOD) state, in the case of the Bricklin EV-1 the low cut-off
discharge of each cell should be 2.5 Volts (120 Volts). For additional safety, this has been adjusted
to 2.6 Volts (~125 Volts).
Once a cell reaches 3.5 Volts the BMS shunts any current provided to a cell to other cells, or if all
cells are charged, simply signals a shut off to the charger.
When the vehicle is being driven and a cell (or pack) drops below a predetermined minimum a
audible buzzer will sound to notify the driver of the low cell or pack condition. Running cells, or the
pack, below the established minimums can seriously damage the battery pack, individual cells, and
possibly other electronic controls, and even the motor. Care must be exercised to ensure the battery
pack is maintained in proper working order.
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Illustration 2: Battery Management System - single
cell module
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