What Advice Can You Give Me About Installing a 72 Volt System on My Steel Sailboat?

Question:

Hi Jeff,

 

First, thanks a million for all the great informative material you are freely sharing with the world. That's the true spirit of the web!  

I have a 20 thousand pounds displacement steel sailboat, I want to replace my failing diesel engine with an electric propulsion system. The replacement system/motor I'm looking at runs on 72V. I would like to feed it from a battery bank made out of 6 G31 Firefly batteries connected in series.  Is this doable?  The reason I'm asking is because I can't find any info on the web about a 72V AGM battery bank. But I find a lot of information about 12, 24 and 48V battery bank. It makes me wonder if there is something technical or theorical going against such a setup?  This would be a battery bank dedicated to propulsion.  It would be recharged by means of a mix of solar, wind turbine, hydro regen, genset and shore power.  - Ben

Answer:

You are correct, a 72 VDC battery bank system is very rare. Personally, I have never seen nor heard of one until this email.  Anything is doable, but you'll be heading into unknown territory  so be prepared to uncover unforeseen situations with a 72 VDC system.  Is there any equipment supporting this system, chargers, controllers, DC to DC converters, etc? - Jeff

You might also enjoy our Tech Talk article published in Pacific Yachting Magazine, "Eco Boating with Electric Propulsion", https://www.pysystems.ca/resources/tech-talk/eco-boating-with-electric-propulsion/