House Battery Replacement

[Wolfpack Fan]

Might have to replace the house batteries. Current configeration is 2 6v wired in series. Considering the same replacment with Trojan 6v golf cart batteries or maybe to 12v Optima blue tops wired parallel.

Thoughts? Opinions? Past Experience?

[Tincup]

I have always used Trojan T105's and swear by them. I just replaced my house batteries with 8 T105 RE 6V Trojans (we FT and only boon dock:-)) and expect to get 5-6 years out of them. Optima's are a good battery but I don't have any first hand knowledge of them.

[BryanL]

don't expect miracles as lead acid batteries are more the same than different

Find replacement batteries from a reputable dealer who sells a lot to folks like you and will stand behind what he sells.

Use only those things the dealer or manufacturer will put their money on like warranty, cost, and data sheets. Do not be swayed by marketing hype, brand names, or other such things that have no specific, measurable, meaning.

The best life for your batteries will be based on your use and maintenance. That means not running them down below 50% state of charge, recharging promptly with a decent multiple stage battery charger proper rated for your battery bank, and applying a maintenance charge with a sulfation inhibiting technique on your batteries when they are not in use.

[paz]

If you're looking at Trojan golf cart batteries and you boondock a lot, you may also want to consider T-125s or T-145s if you have the room. They have the same footprint as the T-105, but they're taller and have a little more capacity.

Also check out Costco or Sam's Club. They sometimes have golf cart batteries equivalent to T-105s at significantly lower price (around $80).

[ralper]

There is more available amp hours in two 6 volt Trojan T-105s than in two 12 volt batteries. When boondocking more is better.

[BryanL]

re: "There is more available amp hours in two 6 volt Trojan T-105s than in two 12 volt batteries."

do not fall for this! -

you don't want amp-hours, you want watt-hours. The usable energy density of all wet cell lead acid batteries is about 12 watt hours per pound and voltage or brand or model does not make any significant difference.

As Paz notes, you can find battery models where the manufacturer has changed the balance in the cost, capacity, and ruggedness trade-off but even then the differences are within the inherent variability in batteries due to temperature, age, cycle to cycle variations, use profile, and other factors.

There are no magic bullets when it comes to batteries (yet. the rumors are fierce about what might be - real soon now! as always).

[coffeeman]

I too in need of house batteries. Here are my local choices:

Trojan T105 $139

Trojan T605 $115

US 2200 $115

Interstate 27 12 volt $115

Exide GC 110 $80

The US Battery will prob be my choice. Local Walmart doesn't carry golf batteries and Sams to far away.

[bob109]

Quote:

Originally Posted by Wolfpack Fan Might have to replace the house batteries. Current configeration is 2 6v wired in series. Considering the same replacment with Trojan 6v golf cart batteries or maybe to 12v Optima blue tops wired parallel. Thoughts? Opinions? Past Experience?

Suggest you read the following before you make a decision

The 12volt Side of Life (Part 1)

http://www.marxrv.com/12volt/12volta.htm

[RJay]

Wolfpack,
Do yourself a favor, fit the largest size batteries in the space you have available. It may not give you all the capacity you need but at least you will have all the capacity you can carry. The rest is up to you to use good energy management. Whether you go 6 volt or 12 volt batteries look at the dimensions in the manufacturers specifications and choose the configuration that gives you the most amp/hour capacity.

[coffeeman]

Quote:

Originally Posted by coffeeman I too in need of house batteries. Here are my local choices: Trojan T105 $139 Trojan T605 $115 US 2200 $115 Interstate 27 12 volt $115 Exide GC 110 $80 The US Battery will prob be my choice. Local Walmart doesn't carry golf batteries and Sams to far away.

Found US2200 locally delivered for $95 each,

[pkmesser]

Quote:

Originally Posted by ralper There is more available amp hours in two 6 volt Trojan T-105s than in two 12 volt batteries. When boondocking more is better.

Consider this:

There are walls between cells (plastic). 2, 12 volt batteries have twice the intercell walls that 2, 6 volt batteries have. Walls take up space. Therefore, for the same real estate, more lead and more acid can be put into the same volume with the 6 volt, vs the 12 volt option. You need to evaluate the numbers, but this is the reason that the 6 volt option can be better.

[wirelessenab]

Quote:

Originally Posted by BryanL re: "There is more available amp hours in two 6 volt Trojan T-105s than in two 12 volt batteries." do not fall for this! - you don't want amp-hours, you want watt-hours. The usable energy density of all wet cell lead acid batteries is about 12 watt hours per pound and voltage or brand or model does not make any significant difference.

I must be ignorant about something! What is the difference between amp-hours and watt-hours other than the circa 12 volt multiplier?

In my education 1 amp-hour at 12 volts equals 12 watt-hours.

Ok so our "12 volt" batteries actually run at 12.5 volts or so. Adjust the equation for the actual voltage of your batteries.

[hamguy]

Quote:

Originally Posted by BryanL re: "There is more available amp hours in two 6 volt Trojan T-105s than in two 12 volt batteries." do not fall for this! - you don't want amp-hours, you want watt-hours. The usable energy density of all wet cell lead acid batteries is about 12 watt hours per pound and voltage or brand or model does not make any significant difference. As Paz notes, you can find battery models where the manufacturer has changed the balance in the cost, capacity, and ruggedness trade-off but even then the differences are within the inherent variability in batteries due to temperature, age, cycle to cycle variations, use profile, and other factors. There are no magic bullets when it comes to batteries (yet. the rumors are fierce about what might be - real soon now! as always).

Amp hours-ARE = Watt-hours at the same voltage.

One watt = 1V * 1A.

[BryanL]

oh my. I wonder why the topic gets so heated.

The problem is that many forget to take into account the voltage when thinking about battery bank energy capacity and that can lead to errors (such as above). By multiplying the amp hours for a battery times its voltage, you do get watt hours and watt hours can be directly compared.

There are other advantages to using proper energy units such as watt hours. For instance, in regards to lead acid batteries, the available energy capacity is about 12 watt hours per pound when energy is drawn (i.e. power) at a watt per pound.

The same sort of thing goes with loads. There, the comparison is usually between 110v circuits and 12v.

Then there are the solar panels, which are rated in watts and, with modern controllers, an amp view on input and output can also be highly misleading.

Then there is your electrical power bill at home. That is for kilowatt hours and, by using the same units for your RV energy store, you can better compare the energy constraints in your RV to something you experience every day.

And, of course, there is the expression of the 'true deep cycle 6v golf cart battery' mythos which has cost a lot of RVers unnecessary expense and effort because people seem to like myths rather than measurement and reason - but that's a whole 'nother topic ...

Of course, if you want to, you could use food calories (a 2,000 Calorie diet implies 100 watts over 24 hours) or ergs or something and your speed in furlongs per fortnight and so forth.

But if you want to avoid errors and be able to figure things out easier and to fit with what you know, proper units can really help in the effort.