PFC CHARGER &
DC/DC Converter
The PFC Charger and DC/DC Converter are both enclosed in a single splash-proof aluminum heatsink
case. The PFC Charger is completely isolated and has 1200W output charge capability and is configured
at the factory. It also receives signals from the BATMON boards to modify the charging voltage at the
battery pack from Charge to Float output voltage. While it may be noted the battery pack would become
unbalanced due to a low power 24V tap for the Power Center, the re-balancing activity during the charge
mode refreshes each battery as it reaches the charge limit imposed by the individual BATMON board
placed on each battery. Any battery that is reaches the charged voltage sooner is then placed on a
dissipative limit so the battery is not overcharged or over-voltaged. The current is then diverted to the
batteries that are not at the BATMON limit. When the charge current drops to 1.5A, it switches to Float
mode by the Charge Detector. The Charge Detector can switch between Charge and Float mode to
prevent gassing the pack from excessive charge current. The cyclic action repeats until AC power is
removed. This ensures all batteries are charged fully regardless of the unbalance incurred by circuits
connected to taps on the pack. If any battery becomes overly discharged for any reason during EV
operation, the BATMON board imposes  a power limit at the Power Center, reducing the chance of
internal damage to any battery in the string due to a reversed cell. Thus the charging process is focused on
proper feeding of the batteries while the BATMON boards watch over each battery individually during the
charge and discharge process. Power dissipation at the BATMON boards is also reduced due to the
cyclic nature of this charge methodology.

The DC/DC section is completely isolated and capable of 13.5V @ >50A output. The DC/DC section is
enabled by an optocoupler signal from the VEHINT circuit during powerup, remotely turning on the
DC-DC converter. It is fully off when the DC Enable is not powered. System protection is provided by
external fuses.

Due to the large heatsink area, a cooling fan is only needed for charging. A 120VAC fan suits this purpose
well.
Older Gen 1-1.5 Charger / DC-DC