64thunderbolt wrote:
ktmrfs wrote:
I'd go with the GC IF your typical current draw is reasonably low like 25A or less. This sounds like your case.
If you typically are going to run an inverter with a heavy load (>75A), then the 12V may work better.
GC have an advantage of having very high cycle life even down to 30% SOC or more, (hundreds of cycles) taking abuse as long as they are kept watered and properly charged etc. However, every battery design has tradeoffs, and with GC it high load current. They have fewer but thicker plates so they have higher internal resistance which compromises high current use.
Since you can repeatedly draw GC down to 20-30% SOC and still get hundreds of useable cycles, the GC wins in the "useable" AH category compared to a 12V. For example a 12V combo of 250AH has realistically 125 Useable AH at 50% DOD, the max recomended for most 12V batteries. By comparison, a 250AH bank of T-125's will give you 250*.7= 175 "useable" AH, That "extra" 50AH could give you an extra day or two of camping.
My last set of Trojan GC were quite often discharged to about 30%SOC, probably about 20 times/year and 50% another 30 times year. After 8 years they went to in-laws and are still running strong for him, better than his bank of 3 year old 12V by far. SG after 8 years is still 1.275 on each cell.
Another thing is how often will you boondock?? If it's only a few times/year, 12V may end up being the lowest cost/year choice. If in a pinch not worrying about discharging the batteries down to 20-30% SOC is important, then GC win hands down. The trojan GC have a higher cycle life at 30% SOC than the trojan true 12V deep discharge do at 50% SOC.
But in either choice the key to longevity is getting a quality battery and properly recharging them as soon as you return from a trip. And unfortunetly, the common WFCO charger in many trailers will seldom do anything near a proper recharge since they seldom go above 13.6V. And you need to get into the 14.5+ V range to properly recharge a flooded cell battery. So you need an iota or Progressive dynamics charger or better yet, the B&D Vector portable charger to get them recharged.
My WFCO 55a will charge @ 14.4 when checked @ the batt with voltmeter. I dry camp exclusively. Been in a camp ground 1 time in 13 yrs and was in a dry site. Last set of 27's lasted 8 yrs. Current toyhauler has 24's and I added a small solar maintainer. No problems staying out 5/6 days with min gen use. Maybe 2 hrs per day total. But we always have sun in Az.
your one of the few lucky guys with the WFCO. Most folks can't get them to go to the "bulk mode" charging, due to the WFCO algorithm and wire size length. If it does, your in good shape and the WFCO is closer to constant current than PD so your actually in good shape.
