Thanks for your intel. If I forgo a second battery, would you recommend both the onboard charger ie. norco genius10 AND a dual purpose start / deep cycle battery?
You’ll want a two bank charger with 10A per bank, you can just tape off the leads of the second bank separate from each other so when you do go to a two battery system you’ll have that charger there for the future or better yet get a single a Victron Energy IP67 25A / 10A charger and set it at 10A. The Victron is more expensive but it’s worth the money.
Whichever charger you choose to get, get one, install it and keep it plugged in whenever the boat is not in use. If you stay with flooded lead acid batteries be sure and check the cells monthly with a hydrometer for balance and overall correct specific gravity, then run an equalizing charge on them monthly, this will give you the best performance out of these tried and true batteries at the lowest cost. I’ve seen quite a few people add batteries they did not need because they fail to maintain their batteries correctly.
When you decide to go to a two battery set up and use the BEP marine switch
You’ll have a super compact and clean set up that only requires you to connect the batteries to. Then you can set the DVSR up to only actuate when the engine is running,
@WiskyDan did a great job on his thread of tying in the fuel pump hot to the DVSR, a simple and clean set up that once done is touch free. This will also enable you to go to a LFP Aka LiFePO4 battery and keep the lead acid start battery isolated from the LFP battery unless the engine is on and charging them both, and will keep the two batteries isolated when at home on the charger, or just stay with flooded lead acid batteries.
But before you do anything but install an onboard charger, you need to install a 500A smart shunt
The SmartShunt is an all-in-one battery monitor, only without a display. Your phone acts as the display. The SmartShunt connects via Bluetooth to the VictronConnect app on your phone (or tablet) and you can conveniently read out all monitored battery parameters, like state of charge, time to go...
www.victronenergy.com
This will allow you to KNOW what the state of charge is on your battery, and to make an educated decision on what size house battery to get. Anything else is just a guess. This shunt will show you in real time what the draw is on your battery in amps, watts, Ah and KWh, and will show you the input from your engine in those parameters and will update the SOC (state of charge) as you cruise in your boat, and the flow of energy from your charger when it is plugged in. It will also show you voltage on your house and start batteries. Both the smart shunt and the IP67 battery charger use Victron Energy’s free app and is super simple to use.