Dual purpose marine lithium batteries now becoming available to replace two 8D wet acid batteries. Will have cranking and house capabilities without lead acid battery needed. To protect marine engine alternators when under way is there a Victron dc to dc charger that will work with only two li batteries in the system?
If you don’t tell them they’ll all work as expected.
The Orion DC to DC should have a lead acid buffer battery to dampen down the response of the alternator regulator. Some people have reported voltage cycling without a battery and it is not recommended. You might be lucky but might not. Some companies sell alternator to battery chargers for use without a buffer battery.
Which Victron dc to dc charger would do the best job with only li batteries in my boat’s 12v system?
Ok. Orion 50amp and set to approximately 50% of alternator amp output. Would it be safe to monitor system w/o a lead acid battery to see what happens in the first spring boat trip…a 2 to 3 hour cruise with a return to home base the next day? I could leave AC charger off over night when on marina 110v shore power so there could be a clear picture of any possible charging issues during the 4 to 6 total hours under way.
Yes I think an Orion xs set to half alternators rated output and monitor for temperature and voltage fluctuations. That’s probably your best bet to make this work without a battery on the alternator side.
It’s unfortunate at this day and age that nobody seems to offer an alternator that would be suitable for lithium batteries!
Thank you, Dave.
My Leece-Neville has no problems, delivers ~ 50a to the chassis and 100a to my battery bank.
All lithium batteries including starting battery?
100Ah lithium starter with 1500a ccp.
2x240 Ah lithium leasure batteries, all with internal, silent bms.
From a german Manufacturer with 15+ years experience.
How long of a life span do you get out of alternators in this configuration?
We run leece Neville alternators on a lot of equipment with lead acid batteries and they tend to fail within a year if they are running near full load for any lengths of time (mostly high intensity led lighting being the issue these days)
These are 170-210a alternators too, and they get incredibly hot under loads anywhere near rated output, which is no wonder why they don’t seem to last
I guess it really more so depends how often the engine is run and how big of a bank it’s charging especially from a low SOC where it’s going to load the alternator to 100% for hours on end. Not really an ideal situation IMO
You’re probably right, i seldom drive more the 2-3 hours, and i have an extra air inlet pulling air directly from the ground to the alternator.
But worstcase placement of engine, spartan me chassis with cummins isb 5.9 “shrink to fit” 
Ludo, could you tell me what dc to dc charger you are using?
None, my batteries are directly connected to the alternator.
Thank you. That is awesome. Do you believe it has anything to do with the type of engine alternator?
No, i think my driving profile and the extra cooling do the trick.
Ludo, your first comment post said “if you don’t tell them”. What do yo mean by thst?
I just connect them like any other battery, generally don’t speak with alternators and ofc also not with batteries 