Quote:
Originally Posted by matoolie
Yep. A proper dual system should prevent drain, but you have to be prepared for when a starter battery suddenly takes a dump. I woke up one morning with my truck completely dead. The starter battery was only at 6v. It had dropped cells overnight. I was able to start the truck with auxiliary battery. In my opinion not having that capability when you have two batteries is not smart. And it can be done with typical solenoid dual systems or jumper cables. Just make sure you have the capability.
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There are some OEM loads that can help run down the starter…. Leaving doors open, lights on, radio on.
I do use my stereo often when camping and because of that moved the main power feed for the head unit to the AUX battery side. It is more work but it was part of my design to ensure that there isn’t anything that I can really do under normal operating conditions that would leave me without power to start the truck.
If you find you use a lot of OEM loads and are unable to re-wire those circuits, then you should consider:
Adding a low voltage disconnect to the starter side
Adding solar to charge the starter to provide supplemental charge
Adding a basic DC-DC converter to charge from AUX to Starter to help supplement those loads.
Use a BlueSea BatterLink ACR which allows you to lower the disconnect voltage, essentially creating a bigger battery as both stay in parallel longer.
Here is a link to a basic DC-DC which would work very well for this.
For $65 bucks, you can have this on a switch to provide 9 amps of charge current from the AUX to the starter. It’s got a remote port so you don’t have to worry about any relays or high current switching.
Victron Energy Orion-Tr 12/12-9A (110W) Isolated DC-DC converter