Re: Building a New battery system, need ALOT of help
Always best to have a battery bank or the same type of batteries and ideally the same age/condition. 2 new batteries would be better for the house bank.
If the electronics are powered by the same bank that is used for starting there can be issues with the electronics dropping out, especially if the bank is small.
An Echo Charge doesn't split the charge. It wires directly between the battery banks. All charge should go to the house bank as that is where it is most needed. The Echo Charge will, when it sees a voltage increase to charge levels, pass up to 15 amps of current to the start/auxiliary battery as needed. A start battery if only used for starting is seldom down more than 1 or 2 AH.
What kind of battery switch do you have? If it is the standard 1/2/both/off switch it can stay. I suggest putting the house bank on #1 and the start on #2.
Run the alternator output directly to the house bank, fused near the battery with an ANL fuse.
The Echo Charge has a ground and 2 fused wires - one to house positive and one to start positive. It will take care of the start battery automatically.
With an Echo Charge as the only link between battery banks the charger/alternator only sees the house bank. The Echo Charge lets you use different battery types so AGM and flooded can co-exist.
With the above suggestions I would run both alternator and shorepower charger direct to the house bank.
To keep things super simple you can use the house bank for all your needs, both house loads and starting. This turns the start battery into an emergency battery - always charged by the Echo and ready for starting or house loads.
I would also suggest a good marine battery charger - its output to house bank only. Iota makes good chargers at reasonable prices.
Living aboard in Victoria Harbour