Wdeertz
Senior Member
Last year I upgraded my house bank to 600Ahr @ 24V LFP batteries. I have Maretron Alerts for monitoring high/low voltages, temperatures and loads with very conservative parameters such that I’d be notified well before the BMS shutdown the house bank. In the event of any catastrophic event my plan was to isolate the LFP house bank and parallel the house bus bar with the start battery. This task could literally be done in under 30 seconds but in some scenarios (think coming into an unfamiliar harbor with heavy fog and the house bank bms craps out from some catastrophic event) leaving the helm might not be possible. As such I am contemplating removing my critical loads (Chartplotter, radar, vhf, running lights, etc) from the LFP house bank and running from AGM batteries.
See attached file for a portion of my electric schematic.
Option #1 is to remove 24V NAV Panel and 12V DC converter loads (see bottom right of picture) from house bus bar and wire into the parallel switch (middle left).
I would wire into the starter battery side so I’d retain the ability to parallel the house loads in an mergency. These loads typically average 20-30amps while underway so the 80A dedicated alternator should be able to keep the batteries fully charged. While at anchor the loads are maybe 2-3amps so going between generator runtimes shouldn’t be an issue. There is a dedicated 60A AC battery charger to charge while on generator. If I go this route I’d like to add a battery monitor shunt to monitor this battery. Would a 500A battery shunt be able to handle the short surge draw of 700-800A during starting?
Option #2 is to take the 24V NAV panel and 12v DC converter loads to their own dedicated 100Ahr AGM battery bank. I’d add a DC to DC charger to keep this new bank charged. Downside is yet another bank (24V house, 24V start, 24V NAV/COM and 12V generator).
I’m leaning towards option #1 but appreciate inputs. Let me know if you think I’m overthinking this and this risk mitigation change is unnecessary.
See attached file for a portion of my electric schematic.
Option #1 is to remove 24V NAV Panel and 12V DC converter loads (see bottom right of picture) from house bus bar and wire into the parallel switch (middle left).
I would wire into the starter battery side so I’d retain the ability to parallel the house loads in an mergency. These loads typically average 20-30amps while underway so the 80A dedicated alternator should be able to keep the batteries fully charged. While at anchor the loads are maybe 2-3amps so going between generator runtimes shouldn’t be an issue. There is a dedicated 60A AC battery charger to charge while on generator. If I go this route I’d like to add a battery monitor shunt to monitor this battery. Would a 500A battery shunt be able to handle the short surge draw of 700-800A during starting?
Option #2 is to take the 24V NAV panel and 12v DC converter loads to their own dedicated 100Ahr AGM battery bank. I’d add a DC to DC charger to keep this new bank charged. Downside is yet another bank (24V house, 24V start, 24V NAV/COM and 12V generator).
I’m leaning towards option #1 but appreciate inputs. Let me know if you think I’m overthinking this and this risk mitigation change is unnecessary.
