I've more or less decided on a particular brand of battery
however just pondering the number, AH and voltage to get. I have a large battery box
so thats not really a limitation. I'm looking at between 400 and 600AH total for a house bank. I thought I'd be paying the same $ per AH but the cost varies significantly depending on the battery
Option 1 - 2 x 400AH 6v (400AH total) $942 ($2.36 AH)
Option 2 - 4 X 120AH (480AH total) 12v $1340 ($2.79 AH)
Option 3 - 2 x 260AH (520AH total) 12v $1608 ($3.09 AH)
Per AH having 260AH batteries are just over 30% more expensive than the 400AHs in option 1. Is there any reason to pay the additional 30% per AH for the 12v 260AH batteries? I've heard that if a cell fails in a battery in series the whole bank fails where as a bank in parallel is more forgiving but is that risk worth paying 30% more.
Or is going with option 2 where you have more batteries in parallel a better option. At least would be a easier to lift
in and out of the boat.
Also the 400AH 6v batteries provide 3.5AH per kg where as the 260AH provide 2.9AH per KG.
On the face of it the 6v batteries in series are significantly cheaper and lighter than the 12v batteries on an AH basis.
Am I missing something? Is there some other issue with 6v batteries. For this particular company they must be cheaper to manufacture and more efficient than 12v batteries.