6 Volt Battery Question

[GaDawgFan]

If it was not for bad luck, I wouldn't have any at all. I am finally ready to take the plunge and trade out by two 12 volt house batteries for 4 Trojan T-105 6 Volts. I just went and measured the slide out battery tray in my motor home and discovered that the width of the tray is too narrow by 1.25 inches. I went on Kwikee's website (manufacturer of the tray) and the do not offer any alternatives that will work. The only other option that I can think of is to find another 6 volt battery manufacturer that may make something that will fit in the available space in my battery tray. The tray measures 13 !/4 by 21 1/2.

If anyone has any suggestions I would love to hear them.

[BryanL]

Don't get stuck on 6v. There is no advantage despite all the hype. You get the same energy capacity per pound of battery no matter the voltage and the life span has more to do with how you use and maintain your batteries than anything else.

Modifying the existing tray can be rather expensive so it is usually best to find batteries that fit what you have.

You can probably find a lot more variety in 12v battery sizes and that will give you more options about how to get the most capacity for the space available.

[Jerry Kraft]

GoDawgFan, I bought 6 volt golf cart batteries at Costco. They were $75 each.
They measure 7-1/4 inch by 10-1/2 inch. That still may be a big large, but I think it is closer. Are you sure you can't cut out one side of the tray to gain enough room? Good luck. Jerry Kraft

[DaveyD1]

GaDawgFan,
We have a 2007 Itasca Meridian and switched from the 3 12volts to 4 6 volts.We got them at Costco as was said in pior post.They fit in the current tray with no mod's made.I have found that they do last a lot longer than the 3 12 volts.Did not need to buy more cables just use what you got and good luck.Search the Winnebago site for batteries and you will find some good pic's on how to do it

[MrTransistor]

To get real technical, you actually do get more battery with 6 Volt. For the same technology and the same manufacturing technique, if the battery dimensions are exactly the same and the weight is exactly the same, the 6 Volt battery has three cells with 2 dividers and the 12 Volt battery has 6 cells with 5 dividers. Those three extra dividers take up space and weight that could be used for lead and acid. Oh, give me a break, what, a quarter Amp./Hour at best?

Now for a little sanity on my part. For all practical purposes, there usually is no advantage to going with 6 Volt batteries unless you are going to install four instead of three 12 Volt. The wiring is easier to balance with the four 6 Volt. Also two 12 Volt are easy to balance. Three 12 Volt batteries will not exactly balance (lead resistance) but close enough for RV use. I would not use three in parallel for starting purposes because the high current exacerbates the resistance problem.

The 04 Horizon house battery tray is 14 ¼ x 22 ½ inches and therefore allows for four Lifeline 6 Volt AGM batteries to be installed. That extra inch in width is screwing you up. I would recommend sticking with three 12 Volt batteries and if you really want AGM (my personal favorite), then try a Group 31 like the Lifeline GPL31T. These should fit nicely and will give you 315 Amp./Hour of capacity compared to four of the GPL4CT at 440 Amp./Hour. Seems like the newer coaches are using the slightly larger trays.

Could you get more Amp./Hours with flooded? Yes. Probably as much as 360. But then you loose the advantages of the AGMs. If the flooded batteries can be discharged to say 50% for 500 cycles, that equals 90,000 Amp./Hours. If the AGMs can tolerate 75% discharge for 900 cycles or more then they yield 212,000 Amp./Hours. or more than twice as much. Base your choice more on how you will use them. If you are a once a year camper or even once a month, then flooded is the way to go financially. If, on the other hand, you travel almost weekly and live in the RV pretty much full time and use the batteries a lot, then the AGMs may prove to be more economical in the long run.

[D in Davie]

Thanks MrTransistor
That was the best explanation I have been able to find. I will replace my 2 dead 12 volts with the same type until I am ready to go full time. If that ever happens I'll just trade the whole coach.

[BryanL]

To get real technical, you actually do get more battery with 6 Volt.

anyone who looks at a spec sheet can see that this is not so.

It is amazing how these myths continue when the readily available specifications show just how wrong they are.

If you want to make good decisions, go by actual measurements and not bald assertions based on false rationalizations.

Also keep in mind that nearly everything battery - cycle to cycle variance, temperature, age, and load profiles - can make a difference of ten percent or more. Splitting nits is not going to help decisions.

[jdsr]

I could be wrong but its not that the 6 volt will give more but I believe it can take more(charges that is). Maybe some of the sparky's out there can correct me if Im wrong but arnt the golf cart(6 volt) batt's able to take more charges and discharges and last longer than the 12?

[BryanL]

re: "its not that the 6 volt will give more but I believe it can take more(charges that is)." - the best answer to this is at the Az Windsun FAQ and the answer is that it depends upon the battery and not the voltage.

The fact is that even SLI batteries will cycle more than most RVers need for a typical 5 year lifespan. But there are reasons why it is difficult to find ratings for number of cycles as the variance between batteries can be large and there are a lot of variables to consider. That is why warranty is the most useful indicator in this area for a prospective battery buyer.

The fact is that cost, capacity, and ruggedness are the main trade-off factors in batteries. Compare the T105 and T145 for 6v Trojans and the SCS200 and SCS220 for 12v. Voltage is only a factor as far as bank wiring, not anything else. Retailers often choose which batteries in a manufacturer's line to offer but that doesn't mean that what you can get in a particular store is all there is.

Check the hard data and you'll find those 6v myths often bandied about in these forums have no substance.

[DAN L]

GO D...
I was able to use 2 gpl-6ct 6v lifeline 300 amp hr batteries in series on their sides in the same space of the original 2 12v 200 amp hr setup, a 50 % increase in capacity.
they are tall batteries laid on their sides. 10.22 X 7.06 X 12.65". The top (end in my case) actually needs 13" for cable clearance. i use wood strips cut to size to hold them in place.
i got my batteries from bd batteries online. they were expensive, but their price includes shipping. they have been working well for over 2 years. they should last 10+ years. i don't ever have to add water either.

[wa8yxm]

Far as I'm concerned the major difference between 12 volt and six volt is final cost, plus perhaps a bit of life.. Now,, I'm not that keen on Trojan's though they are the Cadillac of the industry. I"m not sure the additional quality of a Trojan is worth the additional price when compared to say Johnson Controls from Costco.

Is it possible to modify your battery tray? If you have the clearance you can simply lay wood or plastic (Plastic is best) in the tray to bring the bottomup higher than the lip.

Extend the base of the tray out and glue/attach a rail on the end of the platform. then set the batteries on it.. (This assumes a tray, not a box)

I can draw a picture if I must but basically is is like this

|==-==========-==|

Now.. Johnson Controls, it seems, is also now days making a maintence free DEEP CYCLE 12 volt.. I think it's a group 31 profile (But am not sure) Wall Mart sells it.

This battery makes no mention of CRANKING amps (CA or CCA or MCA) nor does the word MARINE appear on it's label.

[ChasA]

Dan L
Sorry to rain on your parade. But two six volt 300 AH batteries wired in series only gives you 300 AH at 12 volts. And two 12 volt 200AH batteries wired in parallel give you 400 AH at 12 volts. You therefore have lost 25% of battery capacity.

[MrTransistor]

Hi Chas,

I think what Dan was referring to was two 12 Volt 100 Amp./Hour batteries in parallel for a total of 200 Amp./Hours. which would be a 50% increase to two 6 Volt 300 Amp./Hour batteries which would be 12 Volts at 300 Amp./Hour.

I wish that 12 Volt 200 Amp./Hour batteries that were the same size as GPL-6CTs were available. That would be about a 50% increase in energy density. The only way I know of to get these numbers is with Li ion but now we’re talking big bucks!

[DAN L]

Originally Posted by MrTransistor

Hi Chas,

I think what Dan was referring to was two 12 Volt 100 Amp./Hour batteries in parallel for a total of 200 Amp./Hours. which would be a 50% increase to two 6 Volt 300 Amp./Hour batteries which would be 12 Volts at 300 Amp./Hour.

I wish that 12 Volt 200 Amp./Hour batteries that were the same size as GPL-6CTs were available. That would be about a 50% increase in energy density. The only way I know of to get these numbers is with Li ion but now we’re talking big bucks!

you got that right! the key words were "200 amp hr. setup" on the old sulfated 12v deka flooded cell batteries that were in the moho when i bought it.
the lifeline 6ct's were expensive enough without even thinking about li ion batteries. the extra capacity was what made it worthwhile imho.
if my battery compartment could hold the weight (90# each) it would be possible to shoehorn 2 more 6ct's into my battery box if i moved the starting battery.

[dengraham]

Mr Transister,
If I go from my 3 12volt at 100 amp/hr (which I think is a total of 300) and, instead, put in 4 6 volt at 225 amp/hr. Would I then have 450 amp/hr total which should be close to a 50% gain?? It just seems like the way to go??

[capt mav]

Im jumping in with this question, hope its ok
Im replacing my 2 12 volt house batteries this week, had two marine deep cycles in there from prev owner.
I occasionally (once or twice a month) dry camp on beach for a day or two at a time otherwise its parked or plugged in.
WHats the best 12 volt deep cycle out there for me at a good price?
I dont want to hassle with a 6v conversion, just want 2 new 12's
thanks capt mav

[BryanL]

going from 300 AH @ 12v to 450 AH@12v would be close to a 50% gain in energy capacity _and_ in battery bank weight _and_ in battery bank physical size. Battery voltage in the bank is irrelevant. The actual realized capacity is going to have more to do with use and maintenance, temperatures, and age.

WHats the best 12 volt deep cycle out there for me at a good price?

Buy from a retailer who sells a lot to folks that use them like you do and will stand behind his warranty.

If you want your batteries to have a long and useful life, then put your money into upgrading your converter to one that will charge them properly and provide good storage management to assure a top charge and inhibit sulfation.

[capt mav]

Originally Posted by capt mav

Im jumping in with this question, hope its ok
Im replacing my 2 12 volt house batteries this week, had two marine deep cycles in there from prev owner.
I occasionally (once or twice a month) dry camp on beach for a day or two at a time otherwise its parked or plugged in.
WHats the best 12 volt deep cycle out there for me at a good price?
I dont want to hassle with a 6v conversion, just want 2 new 12's
thanks capt mav

thanks for the advice on buying quality, but again does anyone out there have a specific retailer/brand they use at a reasonable price. thanks

[wa8yxm]

Originally Posted by dengraham

Mr Transister,
If I go from my 3 12volt at 100 amp/hr (which I think is a total of 300) and, instead, put in 4 6 volt at 225 amp/hr. Would I then have 450 amp/hr total which should be close to a 50% gain?? It just seems like the way to go??

I will say only this Dengraham......

You seem to have a good understanding of both the math and the facts... Yes, you are correct.

[wa8yxm]

Originally Posted by capt mav

day or two at a time otherwise its parked or plugged in.
WHats the best 12 volt deep cycle out there for me at a good price?
I dont want to hassle with a 6v conversion, just want 2 new 12's
thanks capt mav

Best: Flooded wet cells' Trojan
AGM: Lifeline

They are also the most expensive.

Best bang for the buck may be the big Deep Cycle Maintenance free by Johnson Controls Wall Mart sells (You can also check sam's or costco)

RE: 6 volt conversion hassel

To replace 2 12 v's you need to connect 2 service cables and 2 jumper cables

To replace them with six volt you connect the two service cables and ONE jumper.. So 12's are the greater hassle

And once you are done the two sixes become, electronically one 12 volt battery so you need make NO changes otherwise

NOTE: the "Two service cables" may be half a dozen wires.

Suggestion: 1 day before you start get two small cans of spray paint, One red, One black

On the positive terminal where the service cables are connected (That's the cables that run off to the coach and stuff) spray red paint on the wires

On the negative service cables.. black.

Then go shopping for new batteries, by the time you return the paint should be dry.

Don't forget to turn the old ones in for CORE