Main Battle Tank — Main Engine Off, Systems On During Silent Watch

A leading Turkish main battle tank modernisation contractor approached TEDEG Defence for an auxiliary power unit (APU) for the tanks in its modernisation programme. The modernisation package added new weapon system electronics, communications equipment and climate control to the vehicle, all of it supplied from the 28 VDC vehicle bus.

On watch and standby missions the only way to keep these systems running was to leave the main engine at idle. The contractor passed TEDEG the field feedback from the units together with the electrical requirements of the modernisation programme. The request was for an APU integrated into the hull, needing no separate fuel tank or batteries, with a low acoustic signature, 10 kW at 28 VDC and a fault log for the maintenance crew. The imported APUs evaluated earlier did not connect to the vehicle's control architecture or climate control management, and they added a new external dependency for supply and spare parts.

The field feedback and the contractor's integration team's assessment made the cost of an engine-based watch routine plain:

• Fuel and engine wear: the main engine idled for hours just to supply auxiliary loads. Fuel was burnt for that alone, and engine hours and service intervals accumulated on a vehicle that was not moving.
• Acoustic and thermal signature: the idling main engine was the vehicle's most obvious source of noise and heat at the watch position, which was unacceptable on missions that call for discretion.
• An external generator was no answer: a portable generator cannot move with the vehicle, needs its own set-up and its own refuelling, and creates a second signature at the position.
• Loss of power during maintenance and refuelling: throughout engine maintenance or refuelling the weapon systems and communications went dark and had to be brought back up every time.
• Imported APU integration: the imported units evaluated needed a separate fuel tank and batteries and did not fit the limited volume in the hull or the control architecture.
• No diagnostics: the maintenance crew had no recorded data to point to the source of a fault.

The contractor decided to have TEDEG build an APU that met these requirements.

TEDEG Defence brought the contractor's requirements together in the PowerGuard YGG-DS11 Military APU: 10 kW at 28 VDC from a water-cooled diesel power unit, an IP67 control panel next to the APU and a remote controller that also manages the air conditioning. The unit was laid out for integration into the vehicle design, with no separate batteries or fuel tank.

The YGG-DS11 was delivered to the contractor's tank modernisation programme, and on watch missions the auxiliary loads moved from the main engine to the APU.

• Main engine off on silent watch, with weapon systems, communications and climate control kept running on 28 VDC / 10 kW.
• The APU instead of idling: fuel savings, less engine wear and a low acoustic signature.
• Continuous power to critical systems during engine maintenance and refuelling.
• No separate fuel tank or batteries; the unit is integrated into the vehicle design.
• With the fault code indicator and the latest 500 log records the maintenance crew finds the source of a fault quickly.
• The same architecture, adaptable from 2 to 100 kW, is open to the programme's other platforms.