[PSUBS-MAILIST] Electric Battery Power

[Sean T. Stevenson via Personal_Submersibles]

Diesel engines can only run when a combustion air source is available, which means the submarine must be surfaced or running at shallow depth with an air induction snorkel.  When running engines in either mode, the engine output shaft may be connected to propulsor shafting directly for maximum efficiency, or as is more typical, directly connects to electrical generator(s).  The AC power output of the generator(s) is then rectified to DC and used to charge the batteries, or to power the DC electric motor(s) that drive the propulsor shafting, or both, depending on operational requirements.  When submerging, the engines are stopped, the air induction shafting is closed and mast(s) retracted, and the batteries alone power the electric motor(s) on the propulsor shaft(s).  This pure electric mode of operation is near silent.  Diesel-electric boats are quieter than nuke boats when running submerged for that reason, absent a number of elaborate and very expensive mitigation measures.  Power from the batteries is also drawn off for vessel system and hotel loads, so when the available battery power is low, the sub needs to surface in a safe place, or ascend to snorting depth in a safe-enough place, and run the engines to recharge the batteries.

That's it in a nutshell.

Sean

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Friday, January 11, 2019 8:27 PM, Christopher Cave via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

> Can anyone tell me how diesel/electric submarines, old or modern, convert the battery power to run the engines and provide power for boats systems? A flow chart or schematic included would be very helpful.
>
> Thanks,
> Chris
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