Originally Posted by Canibul
People on this forum told me that I should expect some battery issues after lightning
fried just about all the 12 volt systems on board. Two years later, they're failing. 105 AH lead acids.
So, I need to replace them. What with? Anyone know of any clear winners in the battery replacement game
? We can probably buy more deep cycle lead acid batteries locally at a huge cost, or could import
what we want knowing it will take a week or two to get here.
Is there any way a new Outback MPPT
could fry batteries through a stupid setting on my part? I'd hate to buy four new batteries and then find out the solar
sytems are cooking
12V flooded batteries, in the group 24, 27 & 31 are really deep cycle imposters
including the Trojan 12V G-24, G-27 & G-31... This means they are labeled
as deep cycle
but are really not much more than a label when compared to a GC2 6V.
Some brands will give more "cycles" than others in these group sizes but none really compete directly with a 6V GC2 in terms of cycle life.. As an example Trojan rates their 12V SCS series at roughly half the expected cycles as their own T105/GC2.
batteries it is best to be cognizant of the fact that you are not just buying Ah capacity
you are buying cycle life
too. May boat owners often over look the cycle life
There are 12V golf cart batteries such as the Trojan T1275, and they do have the same cycle life as a 6V, but they are also taller, like the 6V, and a built to use the same plates as a GC2 battery. Most G-24, 27 & 31 flooded batteries simply do not have the plate thickness or cycle life that a GC2 battery does.....
For example in the Deka / Sea Volt / West Marine
line you have three versions all in the same case. Starting
, Dual Purpose
and Deep Cycle
G-24, 27 & 31 12V batteries. However they are only really deep cycle
when compared to the starting or dual purpose batteries with which share the identical case. They are not "deep cycle" when compared to a 6V GC2 or other purpose built deep cycle
Here's the data across the Deka / East Penn / West Marine
Flooded Batteries - Group 24, 27, 31 & 6V GC2
12V Starting - Cycles to 50% = Not Rated
12V Dual Purpose - Cycles to 50% = 200
12V Deep Cycle - Cycles to 50% = 350
6V Golf Cart - Cycle to 50% = 700-1000
*Note: The above are LAB RATED cycles. Expect at least 50% less in the real world..
As one can see the 12V "deep cycle" battery is only a "deep cycle" when compared to the starting or dual purpose batteries it shares a case with.
If you absolutely must buy a 12V G-24, 27 or 31 buy the deep cycle version. In many cases this is all that will fit so a battery such as a US Battery DCXC or the Trojan SCS series will generally be about the best you'll get.. It is easy to see that these are not deep cycle
when compared to a purpose built deep cycle battery.
batteries like Odyssey and Lifeline, in the G-24, 27 & 31 are deep cycle
when compared to other deep cycle batteries in their respective line ups. Most flooded batteries, not so much.
The only batts that have lab rated cycles
the same or close, to their own brands 6V batteries, are Lifeline and the US Battery DCXC 12V series (at least those are the US Battery claims).
I know of no other brand that will rate their G-24, G-27 or G-31 at even half the cycles of their GC2 6V batteries. The 12V Deka / East Penn / WM product is less than half the rated cycles of their own 6V batts...
So it it not just the Ah capacity that winds up being cheaper it is also how long of a life you get that counts too.
In the abusive marine environment real world
I do not see double the cycle life from 6V GC2 batts but I do see longer life, often measured in years. This longer life coupled with GC2's already being less money
than 12V, Ah's to Ah's, means a much lower $$ to watt hours or $$ to lifetime Ah's comparison.
If you can fit the height of 6V flooded batts they are a tremendous value and tough to beat. If you can get to L-16's (considerably taller) even better....