Battery Question

[drjjj]

I know that type(s) of replacement batteries has been discussed before. I know that some owners have changed to golf cart batteries (some with 2 and some with 4), and some have added a 12 volt (so that they have two 12 volt batteries). What are the pros and cons (other than cost) of 1) two 12 volt batteries in parallel vs. 2)two 6 volt batteries in serial vs. 3) 4 6 volt batteries (2 serial, 2 parallel)?

[noneck]

drjjj...its all about Amp Hour Rating and for these units we're not so interesting in Cold Cranking Amps as this specification is more for engine starting capacity. The other factor is that they should be deep cycle which means that can be drained down further than a standard battery and still be recharged...plates are thicker.

[mobrownies]

Unless the batteries are identical, not just make and model, but plate area, specific gravity, etc., they will work against each other if connected in parallel. One will try to charge the other and they won't last as long. Having said that, my truck has two 12v in parallel, but that is a different application, they are there for maximum amps not maximum amp-hours.

If you do a lot of boon-docking, two 6v in series will probably provide more amp-hours.

[OntMont]

Two 6v versus one 12v really makes no difference electrically, but for a given amp hour capacity, two 6v batteries each weighing around 50-60 lbs are easier to handle than one 12 volt battery that would weigh in at 100 to 120 lbs for the same capacity. I have two Trojan T-105 6v golf cart batteries, and find that they meet my needs for weekend dry camping in summer or over-nighting in cold weather with lots of furnace operation. Everyone is going to have a bit different lifestyle, and battery requirement.

[DonPd]

I have been thinking of changing to two 6v batteries. I would need to change the battery box. My guestion is, where to get the box?

[OntMont]

Look for "Blue Sea" brand on ebay etc. They make a good box specifically for two 6 volt G.C. batteries (T105s)

[padredw]

Several of us have used the "Bluesea Battery Box". Here is a photo:



I have also posted a one page document describing my installation in our Montana 2955RL. The same notes might well apply to other Montana models.

Battery Box Install

[Carl n Susan]

The Bluesea boxes are nice, but pricey. And if you wanted to install four golf cart batteries (my preference), they don't make one box to hold them all.

There is a company in WA that has a full range of battery boxes at a less expensive price.

http://www.alliedbattery.com/boxes.htm

I used one and I love it. Picture available as soon as it stops raining.

[illapah]

Got this from the Optima Battery site:

****QUOTE *****
Question: Are 6V batteries superior to 12V batteries for deep cycle applications?

It's popularly believed that 6 volt batteries are better for deep cycle power applications than 12 volt batteries, but it isn't true. This myth likely developed from the fact that golf carts use 6 volt systems. Because golf cart batteries were the only deep cycle batteries widely available for many years, the best way to obtain good 12 volt deep cycle power was to connect two 6 volt golf cart batteries in series (or more batteries could be connected in a combination series and parallel configuration for higher voltages like 24 volts or 36 volts.) The effectiveness of that approach owed entirely to the design characteristics and quality of the batteries used, not to the fact that the batteries used produced 6 volts.

In reality both 6 volt batteries and 12 volt batteries are simply built from 2 volt cells; if a battery is built with three such cells, it's a 6 volt battery. If a battery is built with six such cells, then it's a 12 volt battery. To make a 12 volt system by connecting two 6 volt batteries in series is to do nothing more than to build a 12 volt battery with two cases and external interconnection. In fact, every cable end connection results in some efficiency loss, so the two 6 volt batteries, because they must be connected by a cable, will be slightly less efficient than the 12 volt unit.
******END QUOTE********

[MacDR50]

I use two AGM 12 volt batteries with 100 AH reserve per battery. They are spill proof and require no special ventilation hence I do not use a battery box but only hold downs. The positive terminals are protected by terminal covers purchased at an auto parts store. They are true deep cycle batteries which can take continuous 80% draw downs. They store over the winter without hardly any loss in charge. The ones I have are designed for solar systems but can accept the charge rates from the Montana's charging system without any issues. Here is a useful reference on batteries.

http://www.rvtimes.com/columns.php?f...rticle=111#111

[OntMont]

Everything MacDR50 says above is true (at least it agrees with what I have read elsewhere), They are very good batteries for certain applications, but for sheer "bang for the buck", a T105 lead-acid battery is hard to beat. They will give you 225 amp hours per battery. It comes down to a trade off between the additional convenience and performance features of an AGM, and the lower cost and higher capacity of a lead acid. It is your choice.