<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PhilD:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Jesse:
I have seen some setups where there is an isolator installed. Even a switch in the cabin for which batter to use. </div></BLOCKQUOTE>I have a similar setup on my boat, one cranking battery and one deep cycle with a switch (1 - 2 - Both). Something like that would work better for you and allow you to isolate the cranking battery and use the deep cycle for running your stuff. A few leads and a switch/isolator added to the above setup would work fine. </div></BLOCKQUOTE>
And I've looked into some voltage sensing relays that route charge to both batteries when you have charging current going to the main batter, but disconnect the relay when the charging current goes away. There are some fancy (somewhat pricy) variants of this which add a manual override to connect the backup battery to the starter battery even if charging current is absent so that you can leave all your accessories wired to the main battery, have a second battery getting charged all the time, and beable to use the second battery in a pinch.
I think the vendors call these battery combiners. West marine has one but it isn't rated for starting current. Xantrex makes one called
the PathMaker. You could surely wire up something from cheaper components if you wanted to save your money.