Real Submarine Technology & History Q&A

[DaveyJ576]

Originally Posted by eljeffo41

How long did a fleet boats battery last? Did they have to cut a hole in the hull to replace them? I would imagine the individual batteries were very large and heavy! Probably not a job anyone would look forward to!

A fleet boat battery cell was 4.5 feet high, and 21 x 15 inches wide. It weighed a little over 3/4 of a ton. Not your average Duracell by any means! There were 252 of these cells in two separate battery wells. Normal life span was about two years, but this could vary depending on operating conditions.

These Exide and Gould lead acid batteries achieved this fairly long life at the expense of power output. Their German counterparts had a much higher output resulting in a greater submerged speed. But, the German batteries took longer to charge, they produced high amounts of hydrogen gas, and had a much shorter life (and thus were much more expensive).

The cells themselves are contained within a multi-layer hard rubber jar. The inner layer is an impermeable soft rubber membrane about the thickness of a balloon. This membrane contains the battery acid if the outer layer of hard rubber cracks due to battle damage. This type of jar greatly increased the reliability of the battery and thus the survivability of the submarine and was a key feature of the USN boats.

Changing out a battery was normally only done during overhauls in the states. A section of the walking deck in the forward and after battery had to be removed and each indivdual cell craned out one by one. In the after battery they were simply hauled up through the access hatch and off the boat. The forward battery, however, did not have a hatch and thus a hole was cut in the top of the pressure hull so that the cells could be removed. This was a long, difficult, and somewhat dangerous process and was only done when really necessary.