[388991]

All of these replies are not helping your situation. Let me tell you what is going on. You have a variable voltage charging setup in your vehicle which in turn does not properly charge your aux battery. In order to properly charge the aux battery you need a way to get around this. You need a proper DC-DC charger like a Red Arc setup. https://ok4wd.com/brands/redarc/redarc-dual-input-25a-in-vehicle-dc-battery-charger-1 .

I have a National Luna auxiliary setup with a group 31 Odyssey battery that is the older style split charge style isolator and even this setup is not ideal. I just brought this over to the my truck from a previous vehicle and will only use it until I have the time to upgrade to a proper DC-DC charger.

To circumvent the charging issues I have with the National Luna setup/isolator type charging with the variable voltage charging alternator I run my headlights on while driving and make sure to plug into solar while camping or to a proper battery charger when its sitting at home in the garage. You need your alternator to ideally hit 14+ volts to properly charge your aux AGM battery.

The key to fixing your issue is getting a good DC-DC charger (like the RedArc one) and a solar panel. This will bypass the issues you are seeing because the RedArc system is a dual input device. The RedArc setup will pull power from your solar panels first (it has a built in MPPT) before tapping into your vehicle battery. Blows my mind how much wrong information is out there yet people speak like experts on topics they have no clue about. BTW You can buy all the fancy high end batteries you want, if you aren't properly maintaining the battery it all means nothing.

Watch this..