technomadia Posted May 19, 2008 Share Posted May 19, 2008 As full-time technomads, it is very important for us to be able to squeeze as much battery capacity into our trailer as possible. I built a custom battery setup for our current Tab Clamshell that incorporates two 6V Trojan T-145 batteries, for a total capacity of 260 amp hours. Robert tells me that the Oliver's battery tray is 14.25" x 14.25", and he guesses that 11" would be the maximum height you could fit. I've been researching batteries and options to best fill this space. Here are my notes so far. Comments, thoughts, and suggestions are appreciated: ====== Batteries: To get the most capacity for boondocking, maximizing the number of amp hours is key. It is also important to have a high quality battery that can withstand being discharged below 50% capacity repeatedly without damage. Most batteries, particularly "cheaper" ones, are damaged by deep discharge. True deep cycle batteries are better able to handle this. AGM or Flooded Lead: AGM batteries do not need (much) ventilation, and they also do not need to have their water levels occasionally checked. The downside of AGM batteries is that they cost more, require a quality "smart" charger that will not dry them out prematurely, and they tend to have less capacity than an equivalently sized flooded lead battery. The Oliver's battery compartment slide out drawers should makes battery maintenance easy - so quality lead acid batteries are probably not nearly the hassle they would be on a Casita. One question though - how well ventilated is the battery compartment? From Trojan: "Generally, gel and AGM batteries have about 20% less capacity, cost about two times more, and have a shorter cycle life than comparable flooded lead acid batteries. However, Gel and AGM batteries do not need watering, are safer (no acid spilling out), can be placed in a variety of positions, have a slower self-discharge characteristic, and are more efficient in charging and discharging than flooded batteries." Efficiency difference: Flooded is 89% vs AGM is 99%. Self discharge per month 13% for flooded vs 3% for AGM.... This means that an AGM battery will require less solar power to charge, and they will hold their charge longer in storage. Another important trait of AGM batteries is that you can charge them MUCH faster off of a generator, thus needing less run time. But to do this you will need a powerful and very smart charger, the Oliver default 45A is probably not enough to really take advantage of this. 2x 6V or 2x 12V: Six volt "Golf Cart" batteries are common, cheap, and tend to be excellent deep cycle performers. Two 6v batteries wired together in series can often give you more capacity cheaper than two 12v batteries in parallel. The Trojan brand batteries are particularly well regarded. I used two 6V T-145's in my Tab, for a total capacity of 260AH. They are 11 5/8" tall though, potentially too tall for the Oliver. 12V batteries do have an advantage of better redundancy though. If one of your 6V batteries dies, your whole system is useless. But you can still run on a single 12V battery. Trojan Flooded Lead Acid Battery Options: (all 6 volts) T-145 -- 260 Amp Hours - 10 3/8" x 7 1/8" x 11 1/2" x 72lbs -- Too tall for an Oliver? T-125 -- 240 Amp Hours - 10 3/8" x 7 1/8" x 10 11/16" x 66lbs -- Will two of these fit OK? The width may be a tight fit... T-105 -- 225 Amp Hours - 10 3/8" x 7 1/8" x 10 11/16" x 62lbs -- The same physical size as the T-125, but cheaper and less capacity. This battery is very common and easy to find. T-1275 -- 300 Amp Hours - 12 7/8" x 7 1/8" x 10 17/25" x 82lbs -- Two of these 12V batteries will give 300 Amp Hours of power. Based on the Oliver dimensions, two of these should fit, right?? This would be the maximum possible capacity in an Oliver. Trojan 12V AGM: 31-AGM --110x2 Amp Hours - 13 /16" x 6 7/8" x 8 11/16" x 71lbs Concord / Lifeline AGM Battery Options: Concord makes the LifeLine batteries, so they have much in common. These are the best known and most highly regarded AGM batteries available. Concord B-2240 -- 220 Amp Hours (6V) - 10.5" x 7" x 11" x 68 lbs -- 6V / aprox $295/each Lifeline GPL-27 -- 100x2 Amp Hours - 12.01" x 6.6" x 9.25" x 65lbs ($256) Lifeline GPL-31 -- 105x2 Amp Hours - 12.9" x 6.75" x 9.27" x 69lbs ($259) Lifeline GPL-4C -- 220 Amp Hours (6V) - 10.27" x 7.12" x 10.24" x 66lbs ($239) Fullriver AGM: FR31 110x2 Amp Hours / 13" x 6.8" x 9.7" x 78lbs -- Cheaper AGM alternative, new to the US, popular and highly regarded in Europe. Charge efficiency 97%... ===== Concluding Thoughts: It looks like if capacity is your ultimate goal, two Trojan T-1275's will take up all the space in your battery box, and will give you 300 amp hours of glorious power to play with. Trojan T-125 or the cheap and common T-105's are also good options. Going AGM though does have some nice advantages. Two Lifeline GPL-31 batteries will give you 210 amp hours, and two 6V Lifeline GPL-4C's will cost a bit less, and give you 220 amp hours. Fullriver's FR31 is also a good choice, and will give 220 amp hours potentially a bit cheaper than Lifelines. I need to research the quality and price differences a bit further. Thoughts? Comments? Any other ideas? - Chris // http://www.technomadia.com Link to comment Share on other sites More sharing options...
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