Although there was some variation in the GUPPY conversion programs, generally the original two Sargo batteries were replaced by four more compact Guppy (GUPPY I and II only) or Sargo II batteries via significant re-utilization of below-deck space, usually including removal of auxiliary diesels. All of these battery designs were of the lead-acid type. This increased the total number of battery cells from 252 to 504; the downside was the compact batteries had to be replaced every 18 months instead of every 5 years. The Sargo II battery was developed as a lower-cost alternative to the expensive Guppy battery. All GUPPYs received a snorkel, with a streamlined sail and bow. Also, the electric motors were upgraded to the direct drive double-armature type, along with modernized electrical and air conditioning systems. All except the austere GUPPY IB conversions for foreign transfer received sonar, fire control, and Electronic Support Measures (ESM) upgrades.