Do you plan to boondock? If so, install as many amp-hours of storage as will fit the compartment without overloading the weight capacity. Use what ever voltage maximizes capacity.
Deep Cycle Marine type EverStart 12 volt battery, available at WalMart with a 2 year warranty. Get one with the newest manufacture date on the top.
My posts shouldn't be taken for factual data. They are purely fictional, for entertainment purposes and should not be constituted as actually related to scientific, technical, engineering, legal, spiritual or practical advice. Amen.
Absorbed Glass Matt batteries (I am not sure what kind Sears sells, and have not looked at the link) tend to cost more than lead acid batteries on a capacity per $ rating. The AGM battery also tends to last less time. I don't plan on buying them.
However they do have a good use. Such as my portable starer booster, with a 400 watt inverter and air compressor built into it. It has a pair of 10 amp hour batteries built into it.
Also there is a guy building a trailer to take to ski trips, and if mounted in a warm area, the AGM battery will provide more amp hours than one mounted in the cold area and vented outside. The AGM will not need to be vented, and can be put under the couch, inside without a problem, where it will be warm, and perform very well on a 10F night.
My batteries are outside, so they get cold, and have reduced output. Yet I am not to worried, because I have 440 amp hours, and a 415 watt solar system to recharge them the next day. Usually I go through about 120 amp hours per day when dry camping. This is easiely made up with the solar system.
When my Trojan T-105 golf cart batteries go bad (the first set lasted 9 years, and I gave them to a friend who kept using them) in another 8-10 years, I plan on replacing them with the same kind. So I can highly recommend them.
Because I use Hydrocaps, I only need to add water about every 6 months, and it does not take a lot of water then. I treat the batteries well, and don't run the charger at to high of a rate, usually letting the solar charge at 2- 20 amps.
I guess another reason to use a AGM battery is if you have a problem with theft. Because they can be mounted indoors, no problems.
But the trade off is a pair of 100 amp hour 12 volt batteries might cost as much as my 4 batteries, (440 amp hours total) and will only last about 1/2 the time. Making them four times as expensive to run over 10 years.
Gel batteries require different charging rates than flooded or agm batteries. They would be my last choice.
AGM would be a better choice and are sealed.
It is better to have one very large AGM than two smaller ones. The fewer the number of cells, the less likely statistically speaking there is to be a failure. Look to see if an 8d jar will fit.
ReverendCharles wrote: I am looking for a sealed gel battery like Sears has, no acid mess or fumes. I need to figure the size out or will 2 smaller one work better?
A single 12V Deep-Cycle battery, designed for Marine/RV use, will be adequate for operating all the necessary 12V systems in the TT. The electrical system must have this one battery, even when hooked up to the 110V/30amp power source in the campground. Without being plugged in to the grid, you should still be able to use the lights, radio, ceiling vent fans, water pump, slide-out motor, and perhaps, the furnace blower, just on DC battery power. I would be very suprised if your unit did not come equipped with this single unit. I added a second Deep-Cycle 12V battery, wired in parallel, so as to double the amp-hours of use. Some would claim this double set-up might last 4-5 days without recharging. We've never had to use them in extreme boondocking situations, but the peace of mind in knowing the power is available is priceless.
* This post was
edited 10/08/11 02:51pm by wilcamp *
Wil, Tara, Nakeeta (Alaskan husky 6 yr.-old), and Keeko (Jack Russel/Chihuahua mix 3 yr.-old)
(Joey our 6-yr. old Jack Russel mix, passed over the Rainbow Bridge 12/19/09.)
2008 Jay Flight 24RKS; 2006 Chevy Suburban 1500 4X4 Z71
Be cautious when buying marine type batteries at Wally World etc., if the word "start" appears in the name it is not a deep cycle battery, it is a cross between a starting battery and a wanna be deep cycle. Batteries on a TT need to be pure deep cycle as they have no starting function whatsoever. Deep cycle batteries have thicker plates and can be more deeply (and often), discharged. The best deep cycle batteries are AGM's. While initially pricy over the long term they are superior to any other. They can be more deeply discharged than conventional wet cell batteries, are far more efficient, they are sealed and can be placed almost anywhere including on their sides back etc and they can be charged like a conventional wet cell though some new chargers actually have dedicated AGM charging cycles.
If money is no object get a pair of AGM's but bang for the buck it is hard to beat a couple of 6 volt golf cart batteries wired in series, I like Trojan's with the T-105 and T-125 being their most popular models. Don't waste you money on Gel's.
The whole battery discussion swings on what the goals are.
If you want the minimum number of cells then six individual two volt cells is the best of all worlds (600 amp-hours per cell, and up).
If there is room for an odd number of batteries and the choice is between six volt and twelve volt jars, twelve volt wins on capacity.
If there is room for only two batteries twelve volt wins on redundancy and six volt wins on the number of cells.
If a large inverter (1500 watts and up) is to be run at "full bore" then twelve volt wins even against six six volt (assuming equal amp-hours of capacity), due to the larger voltage drop exhibited by the thicker plates.
Flooded cells remain, for the time being, the "best bang for the buck", but the trade off is regular maintenance and a pair of wool pants.
If one does go to agm chemistry, it would be wise to heed the advice of the particular maker on charging parameters, given that the cost of such batteries may far exceed the cost of a good converter.
Most RV's are woefully low on amp-hours of capacity, and many folks abuse their battery bank by going to far lower states of charge than is good for longevity. To me, it is a no brainer to maximize the capacity.
Balanced wiring for battery banks is often hit and miss (mostly miss, I fear). It should be addressed.
No matter what voltage or chemistry is used, good charging practice need to be followed. If that is done, 2 volt, 12 volt, and 6 volt battery banks may last many years.
So, find out the goals, use what ever works for a battery bank, and go camping!
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