DC/DC Converter
Gen 2
The PFC Charger and DC/DC Converter are both enclosed in a single splash-proof aluminum heatsink
case with a DC cooling fan. It eliminates the cross bracket fan support with a new direct fan mount and
enclosure mounting scheme. The PFC Charger is completely isolated and has 1200W output charge
capability and the charger is configured at the factory for a given battery pack voltage. Gen 2 also supports
the full International voltage range of 120-240VAC, 50-60hz.
The charger receives signals from the individual BatMon boards to modify the charging voltage at the
charger output depending on the activity on the BatMon OVP signals. While it may be noted the battery
pack would become unbalanced due to tapping the pack for bias voltages for the Power Center and fan,
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 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. For Gen 2, the Charge Detector
circuit is not used. Instead, the charger maintains the cyclic voltage at the battery pack until the charger is
unplugged. This ensures all batteries are charged fully regardless of the unbalance incurred by circuits
connected to taps on the pack. Thus the charging process is focused on proper recharge of the batteries
while the BatMon boards watch over each battery individually during the charge and discharge process.
The BatMon compensates for temperature variation within the pack, even if the batteries are located in
warmer (interior) and colder (exterior) areas of the vehicle. Over temperature variations the charger voltage
will vary accordingly.  

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 48V fan powered from the
charger suits this purpose.
Older Gen 1-1.5 Charger / DC-DC Info