Our move to lithium with specific questions relating to keeping existing components

[Chaff]

Hi everyone,

I have been doing lots of 'internet research' as well as discussing with some electricians. I think I have settled on our 'solution' however due to the desire to recycle existing components from our comprehensive(ish) 1120Ah AGM system I would welcome feedback on some of our specific decisions.

Outline of current system:
L421, 40Hp Yanmars, Standard Hitachi 80A (yeah right) alternators, two x AB12210s, 50Ah 750CCA starters, single 1120Ah AGM bank running everything, Mastervolt Mass Combi Ultra 3000, charging one start and house, other start gets charged from AB12210 only. Mastershunt 500 for house, other battering monitoring is both Lagoon factory system, and a Mastervolt BTM-III, 800W of solar through two MPPTs charging house only. All our various batter monitoring says different things and the Shunt does pretty dubious Ah tracking

Our intentions currently:
Moving to 900-1000Ah lithium (depending on battery type and number). Due to VERY restrictive AUS/NZ standards pretty much must be Victron, adding a Victron BMS.
Adding a further 800W-1200W solar.
Replacing AB12210s with Orion 30A chargers (start to house).
Keeping running ALL systems other than start off house. Direct from house switchable emergency start option retained.

Why this plan?
This appears to be the cheapest way to transition us, initially, to Lithium. I believe all existing components will manage the move, with the possible exception of some cabling. DC to DC will protect the alternators and get 'some' use out of engines when running.

Observations.
Our alternators currently provide very little to no charge to house (probably heat/ age?). Whilst we will get this looked at by the electrician prior to the work being done, I am not after a big alternator upgrade and subsequent alternator regulation at this stage (probably stage II). We will definitely upgrade solar, and don't want to do it all in one go and find out the alternators aren't really required anyway. If we do choose to do the Alternators, then we 'could' swap the DC to DC around at the same time, and go regulated and protected alternators to house, then house to start using the same Orions.

Questions/ concerns.
Are our existing systems suitable for the change? Is there any harm in mixing MasterVolt and Victron?
Is there any problem with my 'wait and see' approach to the Alternators/ DC to DC plan?
Should we go Victron 330Ah or 200Ah and does it matter?
Can I put a switch in so that we can alternate which of our Start Batteries the Mass Combi Ultra charges?
We will replace start batteries at the same time. Can I downgrade the size as they seem pretty chunky currently to JUST start the engines.

I welcome any other comments, concerns, ideas. I appreciate that there may be a desire to post 'just spend the money upfront and do it all/ build perfect solution from the start', believe me we've considered it.

Thanks for any help provided, sorry if this reads like 'just another lithium thread' I have tried to make it specific to us.

Al

[chris in SG]

You don't mention a generator, so I assume you don't have one. If that's the case, I really think you should go ahead with the alternator/regulator upgrade. If you are hoping that the new battery bank will see you through days or weeks of overcast weather, I think you will be disappointed. On the other hand, 1,000 Ah is an impressive reserve, but what is your daily Ah usage? I predict that you will shortly receive alot of expert advice on this thread and most likely you will be asked to explain your 'energy balance'..

[Chaff]

Thanks Chris yes good point. We only run a portable 2kw genny we clag into shore power if required.

Overcast days even with 1600 to 2kw solar is a concern good point.

I must admit we are probably oversized the bank for usage. It's partially based on our current size (knowing we should get waaaay more usable from lithium. I wasn't planning on running all the numbers... haha.

Yes better alternators vice genny for when we need a massive boost is a good point.