Model 3328 (105 amp or 175 amp)

Patent Pending

GPU Starting Unit Model 3328 (105 amp or 175 amp)

These ground power units are designed to perform starting, powering up aircraft systems and maintenance functions. When connected to AC power, the depleted batteries can be charged in a matter of hours with the built in power supply/battery charger.

The 3328 contains a full 28-volt portable battery pack for starting and a large power supply to provide a continuous current at 28.5 Volts DC for maintenance. This mobile GPU can be configured with either a 105 or 175 amp power supply. This will satisfy the ground power requirements of most business jets, and includes on-board air conditioning for the 175amp model.

We also custom manufacture Start Pac® units in various combinations of batteries and 28 volt power supplies to meet customers’ exact requirements.


The Model 3328 GPU is a combination battery pack and power supply.


  • 52 Amp Hours at 10 Amp rate
  • 28.5 Volt DC-30.5 Volts at rest
  • Sealed cells non-hazardous
  • Valve regulated high amperage output lead acid
  • 3200 Peak amps

Power supply/charger

  • 105 or 175 Amps DC continuous output at 28.5 Volts
  • Battery recharge time is 6 hours
  • AC input – 208 to 240 Volts ONLY


  • 250 Amps maximum continuous DC load

The following dimensions apply to each of the 3300s:
L 38″ x W 21″ x H 20″/L 96.52cm x W 53.34cm x H 50.8cm; Handle Height 48″/121.92cm.


  • The portable GPU is rated at 2800 peak starting amps. When plugged into a 220 single-phase AC power, the built-in power supply will provide 105 or 175 amps continuous 28.5 Volts DC current. The GPU is a full 28.5-Volt unit and will give faster, cooler starts on all turbine starting engines. The power supply is large enough to power aircraft on-board air conditioning systems continuously.
  • The 3328 weighs 241 lbs./109.31 kilos and is pulled by hand or tug.
  • Always recharge the GPU battery packs soon after use until the green light appears. Once charged, it is not necessary to leave unit plugged in. If heater is installed, turn unit off but leave plugged in.
  • Avoid discharging the batteries completely as damage to the cells can result.
  • Always recharge batteries soon after use.

BATTERY DISCONNECT: When operating the continuous power supply at 105 or 175 amps and below, activate the battery disconnect. Since the 28.5 batteries actually read 30.5 Volts at rest, leaving the battery disconnect connected will deplete the batteries nearly 50% before their voltage reaches 28.5 Volts. Thus in this situation only one half of the battery capacity will be available for engine starting. By keeping the batteries separated from the continuous power supply, you will have full battery capacity for engine starts. If you need more than 105 or 175 continuous amps, then use the battery disconnect and the batteries will make up any amperage needed.

There are approximately thirty 110 volt and thirty 220 volt NEMA plugs in use. Also, customers have various receptacle at their hangars and MRO facilities and may require specific AC cord length to meet their requirements. Due to these facts, we do not automatically provide AC power cords. If you provide the NEMA plug number and specify the AC power cord length you require we will build a cord to be shipped with your unit for a small fee.


For technical assistance, contact Jim Wurth, chief engineer, directly at (928) 231-4536 or at



All Start Pac™ products come with a 1-year warranty on workmanship and materials. Batteries are cycle-dependent and therefore are not covered under this warranty.

Please handle this unit in a responsible manner. Start Pac™ is not responsible for damages caused by misuse or neglect.


Batteries have no memory effect and can be recharged at anytime. Made in the USA.