1. A wet cell bank of 260 amps will draw itself down by more than that each day. If you have a concern about leaving the boat unattended and without shore power for long periods of time, I would suggest a 20 watt solar panel to keep things topped off.
2. Once the alternator starts charging...the echo charge will sense over 14V rather than the actual state of charge of the house bank. So...both will be charged with the alternator on.
3. Suggest you get a voltmeter or Link system to monitor each bank. From my point of view, I don't care to monitor my start battery as it uses so little current and can thus be checked infrequently as long as I KNOW that my house bank is in good shape...'cause I can always start with my house bank if there is a problem. Still...a small voltmeter is cheap and easy to install if you need that assurance.
Go with the echo charge!
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