All portable electric devices, from cell phones to electric
cars, require a battery. For economy, rechargeable batteries are
better. In simple applications these can be used as dumb power sources
but when performance is an issue a "smart battery" (a battery with a
management system) is preferred.
A battery management system monitors the state of a battery and has
control over charging and discharging. The purpose of the device is
- Reduce the risk of damage to the battery.
- Make the most efficient use of the available energy
- Provide information about the battery state
A battery will last longer if used properly. The BMS should prevent overcharging, overly deep discharge,
excessive current draws and high temperature situations. This is
especially important with Lithium Ion batteries where misuse can end
in thermal runaway, explosion and fire.
Some BMS include a DC/DC converter output to the load. This
enables the system to supply the correct minimum voltage required,
instead of wasting energy over the whole voltage discharge curve.
A BMS will try to track its battery's State of Charge (how "full"
the battery is). This is required to control the charge/discharge
process, and is also useful information to pass onto other systems or
the user in the form of a remaining energy indicator. A sophisticated
BMS will track the degradation of the battery over its lifetime.