Dual battery system.. help!!

Mounted one in the back before, won't do it again. You would be looking at long runs of #2 or #1 wire if it is set up as a dual system. A stand alone lithium with solar panels would work better. You will also have to get a solar controller and monitor and perhaps an inverter.

 

roadkill used to run red and yellow tops in all their projects because optima was a sponsor. they once said that all of the batteries they got were returns. they went through a lot of batteries...

the main advantage to optima batteries is the capability to run them in any orientation other than vertical-up, due specifically to their gel absorbed glass mat technology. but the main issue with AGM tech is that it doesn't allow the electrolyte to flow as easily between plates as a typical 'wet/flooded' type battery, and lacking the typical liquid flow characteristics, the gel format can't supply as much power for as long before the gel must cycle itself out to continue generating a voltage differential.

if you're not running the battery sideways or upside down, and the install location allows for a proper battery box to control the gasses or liquids of a typical flooded battery, there's really no reason to run an optima besides show-truck bragging rights.

 

Ok. Now do odyssey batteries.

 

i honestly don't know much about odyssey.

i came onto the scene where mini trucks ruled the shows with wild paint jobs and air bags. and no one would complete a build without a crazy diagonal battery stand to showcase they BOUGHT optima batteries... so most people i knew, myself included, bought optima if we wanted to go big. i had a yellow top in my chrysler lebaron, because i thought that was what it took to be cool. it didn't last as long as a conventional battery, but cost far more, and had no advantage to the 3,000 watt audio system i had in the car.

browsing their site, i think this diagram sums it up nicely


i would agree that flat plates are better than spiral-wound for surface area capacity within the form factor. though it's fun to read optima's battery tech 'benefits' at the same time.
https://www.optimabatteries.com/innovation


oddysey also notes that the battery slowly tapers off towards the end of it's life, where a standard battery just falls flat, and somehow it's better for it to slowly taper.

that's going to be an artifact of the AGM technology, and what i already talked about how the electrolyte can't easily flow between cells to provide voltage.

again, if one's battery is installed in a weird/odd location that venting or orientation is a problem, AGM is a solution to that problem. but if battery positioning and venting isn't an issue, there's no benefit to the extra cost of an AGM over a typical flooded battery.

this was one of the points i learned after i bought that yellow top, trying to be cool. there's a reason that battery manufacturing has stayed mostly the same for so many years, with alternatives with similar power output costing significantly more, not less for the same power output. if the same battery tech could be advanced with more modern materials or designs, the cost would drop, not go up.

flooded plates just plain work, and they work really well. anything beyond that design is suited to a different application that the flooded design has to fight physics to work in, which is why the alternatives cost more to suit the different requirements.

 

Depends on what you do. With a 20a DC-DC You dont need that large of wire. 8ga is plenty for a 20amp system up to 20ft (25ft IIRC), and 20 ft is more than enough to put a battery in the bed (front side of the bed at least).

Flooded are fine if you don't see rough terrain, but start get off the pavement and they often times start leaking. I had a brand new flooded in my trailer when I first built it, one trip to Washington and it was showing signs of leaking, and the starting battery in my truck is showing signs of leaking after a trip to Moab, so both have been swapped to AGM.

 

absolutely where my caveat comes into play.

i'm in the midwest which is so flat, the most 'violent' angle i come across is a boat ramp at any given lake.