[TroutRunner]

Originally Posted by Hants

I don't know the specifics of the Hellroaring system. If your main battery and alternator are both dead and you parallel the backup (self-jump), the backup is going to be drawn down by both the EFI/ECU and other "normal" loads, and ALSO "charging" the main battery.

That said, I haven't seen a high incidence of alternator failures on any forum.

My concern with the Hellroaring system is that high DOD loads (fridge is the most common example) are run off of the MAIN battery. Typical starting batteries have a very low tolerance for repeated deep discharges. ALL batteries have limited (or no) tolerance for repeated 100% discharges. You should probably consider an AGM or spiral cell battery for your MAIN battery with this system.

If your going to run other things that will draw the battery down you must get a deep cycle battery for the main. You can, however, put a starting battery in the back-up position without any problem except for maybe discharging it down during a long winch episode when both are combined.

I went dual deeps (D34M's Optima Blues). I'm assuming the main will fail first from more use. Then I will move the back-up to the main and by a new battery for the back-up. Best to keep your best battery as the back-up.

TR