I am planning to install two victron 200ah lithium battery (in parallel - 12v system), I understand re the External BMS . I am planning to charge the lithium from the AGM starter battery with a 50A victron DC to Dac charger ( my alternator is 115A, No external regulator).
I also have 2 SLA batteries in the bow of the boat for the bow thruster ..
Can I charge the thruster batteries with a second DC to DC charger from the starter battery ?
My set up would have two DC to DC chargers coming from the starter battery ..
Yes you can. The DC to DC for the bow thrusters may be better closer to the thruster batteries.
Great , Thanks for the info ..
moving the DC ToDC Charger near the thruster batteries makes sense ….
Final Q , I know the victron lithium are v reliable but to avoid a boat blackout in the event of the lithium shutting down I am planning a separate 110AGM house battery for the critical loads (Autopilot , nav Instruments and nav lights) .. I plan on using a DC to DC charger to charge this secondary house battery from the lithium bank.
With this set up I would have a small reserve to allow the critical boat systems to function for a period of time ….
The result of this system would be one DC to DC charger charging the lithium form the starter AGM, a second DC to DC charger charging the thruster batteries ( located near the thruster batteries ) and a final DC to DC charger charging the critical load House AGM 110Ah battery ..
This second house AGM battery should never discharge as the lithium should always keep it charged - good for that AGM battery health ….
Does this sound logical ???
Sounds logical even though it is a fair bit of kit.
You could simplify the bow thruster charging by using a battery combiner like the Victron ArgoFET or a voltage sensitive relay as they are both lead acid. The back up AGM needs more of a trickle charge function but I have only seen one that does lithium to lead acid here in the UK and it is as expensive as a DC to DC.
Thanks .. the current set up has a VMR to charge the bow thruster batteries - it has worked v well.. Maybe I should keep that for now …
I know the other setup is a bit more expensive but I would be more comfortable at night with protection from lithium shut down …
Thanks again