Abuse and monitor

My last couple of posts have been about batteries  - the things on boats that are a another disposable item (recyclable for money) but are essential to make being or living on a boat a bit like being in a house... It's a good thing now more houses are getting like boat dwelling in that for some or all of the time they are also now being powered by batteries. 

In the boat situation cheap solar and now lithium  - for the wise, have opened up the options of living like connected to the grid. Lithium is so powerful and so flexible in charge and discharge properties compared to old lead acid tech. 

Home systems such as ours also save money  - my return on investment is calculated at 6 years with much of the tech well able to see past 10 or even 20 years.... it is also essential to allow the grid to load balance  - in winter when little sun for the solar we load up out batteries at 9p per kw and use that all during the day... most days not needing any 29p electricity. Our last electric bill for February into March was £42 and over £15 of that was standing charge. So less than a pound a day. 

Back to the boat and I checked I added two 160a/h AGM ( Absorbed glass matt ) in February 2019 at a cost of £220 each. They are dropping to 50% on the smartgauge quite quickly after a few hours of duty. I could make them last another year and may well do so  - abusing them into the 30% range knowing they are fubarr'd. As in my last post the Ecoflow will be my backup so for now I'll abuse and monitor 

https://nbpercy.blogspot.com/2019/02/the-victron-bmv-712-and-batteries-go-in.html

I'm still unsure how to replace them. On the 12v FB group there is much talk and support on a hybrid system of lead acid and Lithium.... the lead acid being the buffer for the instant BMS ( battery management system) shut of of charging that lithiums have. The benefit of lithium is they will take as much charge as they can as their charge limit is set by the BMS - that is adjusted for temp also. They charge to full then shut off instantly which can bugger up the alternator ( my understanding ) hence the buffer lead acid to take the alternator output when the BMS shuts off. Also there is the concern about alternator over heating as they work hard instantly and stay at max output unless charge rates are adjusted in the BMS  

I'll abuse the resident batteries and watch this space  - one issue is space literally as I'm limited on Percy so that is always a consideration. The other consideration is cost... they are an investment in fit and forget which if we intend to keep the boat for any length of time makes sense... if not it'll be another brace of AGM's. 

Final question I have  - some who read this who know may wish to comment  - not good to leave Lithiums at 100% and if on a solar panel thats what the leads get. I am presuming within the BMS you can set a charge limit so if leaving the boat for a period of time and not wanting to have the Lithiums at 100% you'd set the max charge to their recommended storage setting ? 

Anyhow here is the website of the recommended supplied for interest .