The June/July 2015 Professional Boat Builder has an article called "chemical conversion"
It is about someone who converted a 53.3' Beneteau 2004 Oceanis from an AGM house bank to a Lithium house bank.
It is by Mark Lenci who is a retired CO of the USS Houston and recently worked on cloud services for Microsoft. So I suspect his skills and access to people with skills are a little better than the average guy.
He was able to reduce his generator run time by 70+% which was a primary goal.
He installed two 12V/5,000W batteries.
The article if very detailed. He is expecting the batteries to last 20 years.
It was an amazingly complex project but Mastervolt supplied the batteries and a lot of software and and Electomaax alternator.
The following is a partial list of issues that had to be sorted out.
- Electronic control of the charging system so the system can sense any problems and stop charging.
- Charging profile for AGM is radically different than Lithium. The Lithium wants full amps and volts right up till it is done not the three stage charging we are used to.
- Charging for the AGM start battery for the engine, for the generator and two for the windless.
- Thermal load issues for the alternator.
- Ability to cut back on amps when recharging on low power docks.
In short he apparently pulled it off but mastervolt said they had never worked with an owner before.
The lithium batteries are exceedingly expensive but if they last 3 to 4 times longer and you are keeping the boat the battery is not the issues but the charging and monitoring equipment costs.
The big thing is that you run the generator at full voltage and current until the batteries are full. This puts a bigger load on the generator which is good for it and it is for a much shorter time. Also the lithium can be filled up with a generator as they don't need an all day float to top them off.