The Charger and Batter y Management System • • • • • • • • •
Power factor > 0.99 Maximum charging current: up to 25 A (NLG511) Maximum charging voltage: up to 720 V (NLG514) Accuracy of charging voltage: ±1 percent Short-circuit- and open-circuit-proof Overtemperature protection by linear derating Reverse-polarity protection by internal fuse Switches off at mains with overvoltage Battery temperature monitoring
Additional Functions and Interfaces • Power multiplying can be done by connecting multiple chargers together. • Control pilot enables accelerated charging (mode 3, according to SAE 1772) using the dedicated infrastructure. • All types of charging profiles can be programmed by PC via a serial RS232 interface. • Charging voltage is temperature-compensated. • Actual firmware can be downloaded by PC. • A CAN interface is included. • There is a built-in status display (five LEDs). • There are four analog inputs (three temperature sensors, one power control). • There are four digital inputs (charging profile control and battery current sensor for internal Ah counter). • There are four open collector outputs (three programmable) that can drive relays, lamps, fans, etc.
Battery Management Systems and Battery Balancers The battery management system (BMS) and battery balancers are a few other ways to monitor and/or control your batteries. I feel that this is an important topic to touch on. It could have been placed in Chapter 7, but I think it better suited here. Below I will explain and give a few examples of these two basic systems. For the most part, your EV will not need a BMS; rather battery balancers would work just fine. A BMS may be needed only if you choose to use an exotic battery pack with multiple batteries. For my purposes, I will stick with balancers.
Battery Balancers Since one or more batteries in a series string of batteries can discharge lower than the other batteries, it is important to ensure that this weaker battery receives extra charging. This will ensure increased life of the pack because a weaker battery will drag the pack down and shorten the life of the other batteries in the string. In the worst case, you
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