Sailboat with LiFePo4 for house AND Starter

DIY
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1

Good day, all

I’m an ex-drafter who understands diagrams just fine, but I’m not an electrical guy. I’ve got a small liveaboard sailboat and I’m converting it from AGM Lead-Acid batteries to LiTime LiFePo4 lithiums. There are multiple wiring diagrams here on Victron’s site around using lithium batteries, but they all assume that the starting battery is still going to be a lead-acid battery. Charging tends to thus run from the source(s) to the lead-acid starting battery, then on to the lithium house bank. Does anyone have one showing using the lithiums for both banks?

FWIW, this is what I have:

2x165 AH LiTime batteries for house bank

1x165 AH LiTime Dual-Purpose self-heating lithium for starter battery

Yanmar 3GM30F 27hp Diesel with 80A Hitachi alternator

Zeus External Alternator Regulator

Planning on…

Smart IP43 Charger

MPPT 100/30 for solar (2xRenogy 115w panels)

Probably a Cerbo GX Mk2 for system monitoring.

I know I’ll need a shunt (or two?) for battery monitoring.

Anyway, not looking to design anything particularly high tech here, just a robust system that will support a relatively simple boat. Any help with existing diagrams would be amazing.

Thanks!

SV Shrike

2

There are several reasons for sticking with lead for the starter battery, one of which is that should the starter battery disconnect from the alternator whilst the engine is running at speed, then the Stored energy in the alternator can cause a massive, destructive voltage spike (up to 80V). The other reason is normally the CCA rating of the battery.
Should the starter battery disconnect, then the voltage spike will probably destroy all electronic equipment connected, unless it is adequately protected. The protection would need to be able to dump the max current from the alternator - e.g.100+A.
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A single shunt will monitor the house battery for current and voltage, if you don’t have access to the BMS data (always a good idea). It will also monitor the voltage of the starter battery - which is usually sufficient.
The Cerbo will also process the BMS data. See Battery Compatibility [Victron Energy] for BMS compatible batteries.