INTRODUCTION 



This report discusses the suitability of lead-acid batteries 

 for use as a power supply on the bathyscaph TRIESTE during 

 decents into the hostile pressure and temperature environ- 

 ment of the deep sea. Further information concerning the 

 bathyscaph itself and its operation is contained in another 

 report. ■"■ 



The bathyscaph is not, in some ways, a weight -limited vehicle. 

 It has been designed with buoyancy to support additional bal- 

 last for deeper dives and the heavy KRUPP sphere. Operating 

 in depths of 20, 000 feet or less and utilizing the lighter TERNI 

 sphere or cabin, the bathyscaph has buoyancy to support 

 additional payload. The main problem is space limitation. 



The power supply of the TRIESTE formerly consisted of 

 small silver-zinc batteries. These were extremely expensive 

 and occupied a large part of the available cabin space. An 

 externally mounted power supply would free this valuable 

 cabin space and greatly increase the power which can be 

 carried. Only the limitations imposed by the structural 

 space available to mount the power supply externally and by 

 the weight which may be carried restrict the amount of power 

 supply available. The weight limitation does not become 

 important except during extremely deep dives. Another 

 advantage of the externally mounted power supply is the elim- 

 ination of the need to carry high currents through the wall 

 of the cabin. With the primary power supply outside the cabin 

 only small control currents are required for even the heavy 

 duty propulsion motors. Small control wires may be used, 

 which require less space in the available penetration and 

 eliminate heavy power cables inside the cabin. The present 

 size and number of penetrations in the cabin are fixed, and 

 as more and more scientific equipment is added, more cabin 

 space and penetration are required. 



These factors, the extreme urgency of acquiring a larger 

 power supply, and the much lower cost of lead-acid batteries 

 prompted the initiation of the tests which will be detailed in 

 this report. 



Navy Electronics Laboratory Report 941, The 1957 Diving 

 Program of the Bathyscaph TRIESTE , by A. B. Rechnitzer, 

 28 December 1959. 



