New Beetle BMS General Design

January 2004

Overview

The intent of the New Beetle BMS is to have an integrated monitoring and balancing system. Monitoring will monitor the voltage of each battery, each pack temperature, and the charge and discharge currents. Balancing will use the battery voltage information from the monitor to determine the weak battery(s) and supplemental charge them accordingly. All information will be retained for downloading and historical analysis.

System Design

The system will be based on the Lee Hart Balancer. This design is a centrally controlled battery balancer system which controls remote relay boards at each battery pack. Each of these relays directs supplimental charge power to the individual batteries. The major design criteria is safety: no more than one battery can be charged at a time - and this is built into the hardware.

However, the circuit as is needs modeification to work with the New Beetle project. It will need the following modifications:

• Circuitry to monitor each battery's voltage independant, and at the same time as, battery balancing.
• Ability to measure temperature in each of the four packs.
• Balance up to 4 battery packs with up to 8 batteries each.