From The Encyclopedia of the Arab-Israeli Conflict [4 volumes]: A Political, Social, and Military History 1st Edition by Spencer C. Tucker. ISBN 978-1851098415
From page 961:
Syria acquired three Romeo-class submarines from the Soviet Union during 1985-1986. An older Whiskey-class was also transferred to Syria in 1986 but to server as a battery-charging hulk to support the Romeo boats.
Obviously, the Whiskey class submarine was not acquired to serve in a combat role alongside the Romeo class submarines.
What is meany by "battery charging hulk"? Is there a need for additional charging capacity in some circumstances? Is the vessel able to move under its own power? Are the electrical systems of the two classes compatible? Are they any vessels produced explicitly as battery charging vessels?