6 volt vs 12 volt batteries for boondocking

[placergold]

Hi all, While waiting for our new 28' Stealth toy hauler we're trying to figure out the best batteries to get for when we're back in the hills camped off the grid.

We ordered the optional 200 watt solar panel & regulator with Power Boost. And a 1,500 watt Go Power Inverter.

I've been told the golf cart type 6 volt batteries will last much longer than the 12 volt deep cycle batteries available. Mainly because of the constant discharge/charge cycle that occurs.

But, I really have no experience in this area, so any and all input from those familiar with this subject would be greatly appreciated!

Thank you.

[OldSmokey]

marcsbigfoot20b27 wrote:

OldSmokey wrote:

All 3 of my batteries were bought in the same month....just adding them to the trailer permanently with some 1/0 cable.

not going to make much difference, 2-3 years max and you will be replacing them anyway..

Oldsmokey, still waiting to hear your reason why my brand new AGM batteries will only last 2-3 years?????

sorry for the delayed reply, I have been overseas finishing up a contract.

now back to your issue, i'll try to keep it in laymans terms.


your Duracell agm is a budget agm made by interstate, it's a 'b' grade and not
made to the best standard. battery to battery variance in internal resistance and
capacity is the issue here, when you connect them in parallel the set will behave
( performance wise ) as the worst battery. so in effect you had 2 good batteries
and one not so good and made them into three not so good batteries.

now the situation becomes worse when you actually use them and start to charge and discharge

over time.

for this example your batteries numbered 1,2 and 3 are connected in parallel string
with the take off on battery 1 to your equipment.

you now discharge at 90 Amps. you would think that each battery will supply
30 amps right ?.. well your wrong,

in practise, more current will be drawn from batt 1 than batt2 and batt 3
this is due to cable and internal resistance.
i won't bore you with complex network analysys, but the current distribution
from a 3p string is approx like:

batt 1, 41 A
batt 2, 28 A
batt 3, 21 A

so you have batt 1 doing much more work than batt 2 and batt 3
this also happens when charging, batt 1 will charge first with the others lagging
behind. now, after many cycles of this abuse, batt 1 will age much more rapidly than
batt 3. as batt 1 ages, it has the effect of dragging the others with it as they
attempt to equalize each others voltages. batt 1 drags batt 2 and 3 and batt 2 drags 3


now for fun, just imagine what happens if one battery cell develops a short ??

you guessed it.. the others dump their charge into it at a very high rate
and you get your very own firework show..

now there is a 'trick' that will mitgate some of this and it's simple..
you connect all 3 in parallel and draw positive from one end of the string
and neg from the other.. now you only have one batt underworked..
it's still not good but will give the string a better chance..


you stated you have 360 W of panels..
I can tell you right now that's not enough.. 300Ah of agm will need
at least c/10 to charge. a good mppt cc will be 90% so 360 * 0.9 = 324 W
and 324 W at 12V = 27 Amps.. so you are short even at max insolation.
you need a minimum of c/10 or better still, for agm c/6 = 50 Amps
so you need more like 720 W or so.. and that's probably wrong because we don't know
your actual usage.

and fwiw, that WFCO convertor is not woth the space it occupies and will not
charge your agm's correctly either.

if anyone needs more info on solar/RE i would be more than willing to assist.

[MEXICOWANDERER]

The EXACT positive plate thickness is a manufacturer specification. When I examined that battery I found clues not hard data. My 2013 finding provided compelling clues. Your bumped response above is what prompted me to pursue the data. I am loathe to present clues as being hard data.

Believe what you wish 🙂

You can do your own clue uncovering.

Perform a BCI recognized CCA test on the two samples. 50% of OEM rated CCA in amperes discharging for 15 seconds.

Perform an impedance test on both units.

A CCA test performed on my light 31 revealed a CCA rating of 630 amperes which was conducted at a temperature of around 65F

An inversion of an impedance test was the Lifeline battery accepts 103 amperes at 14.4 volts.

-------------------------------------------------------------------------------------------------------------------------

Is not the ultimate goal to have a product satisfy your own demands? If it works for you that's great. My great limitation is I cannot warranty a 30 day or 30 year battery. That heavily skews my product performance demands. From light bulbs to clothes to appliances that are not available down here, I have to stick with stuff that stays working. I wish it was otherwise.

[pnichols]

MEXICOWANDERER wrote:
I wish I knew the positive plate thickness of the fullriver battery. But weight vs amp hours versus CCA should serve close enough to compare it to the Lifeline.

David .... here's comments you posted on 04/22/17 at 09:56pm.

Your comments in your 2nd sentence above are why I believe that the 72 lb. Fullriver is very close in capability to the 74 lb. Lifeline.

By the way, Fullriver's AGM batteries carry a 7 year warranty:
https://www.solacity.com/fullriver/

[MEXICOWANDERER]

Lin, provided that information which I subsequently verified by telephoning an engineer friend at a battery manufacturing plant. The Fullriver, battery is made in China.

In 2013 I tore into a junk Fullriver group 24. Stripping mats from plates was a mess. With dial calipers I measured .035 or so (memory) to .039 with about 10 measurements. Sorry to be so vague but I neglected to commit data to memory.

And no, there was not an inordinate amount of material in the mats nor in the sediment chambers. That finding is what convinced me to go to Lifeline and never look back.

You do realize "proprietary information" is the sacred cow of competitive manufacturing? If you are truly interested in getting a better handle on your question, contact Concorde battery company and ask "Do you have competitors that have plates greater than .060" thickness". They may decline to answer. In that case refer to the Lifeline PDF manual.

As far as I know, Concorde and Rolls battery are the sole two manufacturers who state plate thickness for all to see. Doesn't take much imagination to see why they do it.

Summary: Even if the Fullriver was 50% of the cost of a Concorde, I would still go with the latter. It has to do with the unavailability of a warranty or getting a replacement down here. I do not wish to save money and lose in the end.

[pnichols]

MEXICOWANDERER wrote:
The Lifeline has .090" positive plates, the Fullriver you use has .040" plates. Apply 14.4 volts unlimited capacity to your Fullriver. Now do the same to a 31 Lifeline. Seeing is believing. The Lifeline will accept close to 100 amperes. Essentially a C1 rate. The Fullriver? Hmmm.

David,

Where can I go to see that Fullriver plate thickness value of 0.40" that you mention? I'd like to confirm which of their models uses that thickness. About a year ago when we last discussed Fullriver battery plate thicknesses, you (and I) couldn't find that piece of information.

I've never pushed my Fullriver AGMs with the recharging equipment necessary to see how close they could come to a C1 recharge rate. The best I've seen to date is during our last drycamping trip this past June. I had discharged the RV's two of them in parallel down to around 12.1 volts. I started up the Ford V10 and let it idle. The ammeter monitoring the Fullrivers went to slightly over 70 amps (very little was turned on in the engine compartment or RV). Not bad for an idling 130 amp alternator system. Perhaps rev'ing up the engine would have shown on the ammeter more current going into the hungry batteries.

I'm not sure I see how plate thickness is related to recharge rate? I would think that is more related to internal battery resistance combined with the capability of a charger to maintain 14.XX volts on the battery terminals while simultaneously supplying whatever current that dynamic internal battery resistance dictated in real time.

As you know, I chose Fullriver over Lifeline because of the Fullriver float voltage being the proper match to my 7345's nominal output voltage - the slight price difference between the two was not an issue.

Here's the exact Fullriver and Lifeline 12V deep cycle AGM battery models I had in mind for comparison purposes when I posted earlier. (Note the error in my earlier post - the Lifeline weighs 74 lbs., not 75 lbs.):

http://www.fullriver.com/products/admin/upfile/DC120-12B.pdf

http://lifelinebatteries.com/products/marine-batteries/gpl-31xt/

[MEXICOWANDERER]

pnichols wrote:

MEXICOWANDERER wrote:

Oooooo and dat's the rub.

There are no group 24 and group 27 batteries that have the .070" plate thickness of the most puny GC220.

Or any of the AGM batteries having anywhere near the plate thickness of the Lifeline.

Or larger batteries having .330" plate thickness of my Rolls cells.

David ... be careful about the Lifeline plate thickness as being the head-and-shoulders champion. Note that we do not know the thickness of the plates in my Fullriver AGM Group 31 115 AH batteries, which weigh a little over 72 lbs. each ... while the 130 AH AGM Group 31 Lifeline batteries weigh arouund 75 lbs. each. Which means that the amp-hours per unit of lead volume of the two brand names is VERY CLOSE. Dividing 115 by 72 equals about 1.60 amp-hours per lb. for the Fullrivers, while dividing 130 by 75 equals 1.73 amp-hours per lb. for the Lifelines.

The Lifeline does indeed win (very) slightly in energy storage per volume unit of lead ... but certain potential buyers of the two brands would have to be able to tolerate the two down-sides of the Lifelines over the particular Fullrivers I'm comparing them to before going with the Lifelines. All this means that plate thickness of the two brand names is very close to the same - since both battery brands are of about the same Group 31 dimensions.

I will try to be quite objective and reserved. The Lifeline has .090" positive plates, the Fullriver you use has .040" plates. Apply 14.4 volts unlimited capacity to your Fullriver. Now do the same to a 31 Lifeline. Seeing is believing. The Lifeline will accept close to 100 amperes. Essentially a C1 rate. The Fullriver? Hmmm. How an it be possible for a battery with a significantly higher CCA rating have a significantly inferior charging (ampacity) acceptance?

Measure 10 square inches of glass mat from each battery. Immerse in 1.300 SG electrolyte. weigh both. Then measure mat thickness. The Lifeline has a significantly inferior CCA rating as compared to the Fullriver. Keep in mind that hugely superior charge acceptance.

Plate alignment in the Lifeline is >.001< due to laser robotics. Misalign plates just .005" and see what happens.

There is a lot more involved in producing a good battery than weight, plate count, and ampere hours. Meticulous attention to construction design specifications is one key difference between an excellent battery, Trojan and a superb battery, Rolls.

The Chinese are loathe to commit AG, silver as a grain structure modifier for grids. yet it is to be honest, quite a plus.

The Mil-Spec qualification process in the USA military would not approve of many absorbed glass mat batteries outside of the Lifeline. Same thing for many commercial passenger aircraft.

My Lifelines are to be handed down to the kids. Call them heirlooms. I do indeed take good care of them.

[BFL13]

Mex, you missed the link with having your internet issues, but it said, "The industry standard is that 30 minutes of discharge time = 1 normal, 2-person, 18-hole round of golf."

ISTR in 2013 the shop said the six 8s did better than the four 12s for golfing, but this year when I went by there (no used batts on hand this summer) they confirmed they were still selling some cars with the four 12s though

[pnichols]

MEXICOWANDERER wrote:

Oooooo and dat's the rub.

There are no group 24 and group 27 batteries that have the .070" plate thickness of the most puny GC220.

Or any of the AGM batteries having anywhere near the plate thickness of the Lifeline.

Or larger batteries having .330" plate thickness of my Rolls cells.

David ... be careful about the Lifeline plate thickness as being the head-and-shoulders champion. Note that we do not know the thickness of the plates in my Fullriver AGM Group 31 115 AH batteries, which weigh a little over 72 lbs. each ... while the 130 AH AGM Group 31 Lifeline batteries weigh arouund 75 lbs. each. Which means that the amp-hours per unit of lead volume of the two brand names is VERY CLOSE. Dividing 115 by 72 equals about 1.60 amp-hours per lb. for the Fullrivers, while dividing 130 by 75 equals 1.73 amp-hours per lb. for the Lifelines.

The Lifeline does indeed win (very) slightly in energy storage per volume unit of lead ... but certain potential buyers of the two brands would have to be able to tolerate the two down-sides of the Lifelines over the particular Fullrivers I'm comparing them to before going with the Lifelines. All this means that plate thickness of the two brand names is very close to the same - since both battery brands are of about the same Group 31 dimensions.

[MEXICOWANDERER]

30 minutes for what kind of game? 18 holes of golf for a foursome is no joke. Figure 15 minutes per hole? About four minutes per person? Four to 5 strokes.

The fewer cars need the more money they make. If, they squeeze more ampere hours under the seat. Golf pros have to impress the owner with hoodoo abstract cost calculations and workups. What sells this stuff is the magical "Ooooo the cars can almost make three 36 hole rounds" ALMOST is the enemy of the golf car 3 cell. The scrubber outperforms it - at the cost of lifespan.

A new scrubber is not a bad battery. But it will misbehave when a GC220 does not. Lose cell's gravity equality and be harder to restore. But this can get to be a semantics quagmire as I am stating observations using a Trojan T-105 baseline.

It pays to keep in mind that an RV golf car or scrubber battery is subjected to a totally different environment than from their intended use. 36 holes then a recharge or 10,000 square feet then a recharge is completely different than a four day dribble discharge then partial recharge. The use permutations are endless as are maintenance permutations. How many folks bother to do anything else except ***** about campsite battery performance, then when they get home they stick the plug into a socket and walk away. Ever see the DIFFERENCE between an RV charger and professional golf or floor scrubber charger?

So if I should hear someone at a golf course spout a tangent about minutes rating of a battery I know their forte is based on comparison and has virtually nothing to do with actual values. Four "loaded" golfers veering all over the rough and plowing through sand traps could consume 5x the kWh of a normal golfer. 9 holes in Phoenix or Atlanta in July may consume a fraction of the power that would be used in Portland or Northern Minnesota. My one and only real golf game at age 18. My high school chum fancied himself as the quintessential Scottish genetic golf guru. Back and forth we went from the pin to the intended target. Silverado Golf Course. I stunned the crowd by making A Hole In Seventeen. I never looked back.

[BFL13]

Mex, my T-1275s were originally in a golf car. The golf car shop had either four 12v T-1275s for 48v or else six 8v batts for 48v per car.

They had some sort of tester, so that when the battery bank could no longer do 100 minutes, they retired those batteries. The ones I got (two years old in 2013) were supposedly good for 86 minutes. They sold those kind at a discount, and those batts with lower minutes like 70 were junked.

I see in this article, that the standard for one game is 30 minutes, but I cannot match up what they are saying in this article with what the golf car shop I was at said (as above) for the 100 minutes minimum.

http://masekgolfcars.com/battery-discharge-ratings-for-golf-car-batteries/

I know about RC rates and AH rates. Anyway, it is all very mysterious, since my T-1275s which were good to 86 minutes also tested out as approx. 86% when I did my initial 20ah rate test. (After some work I got them to 90% as reported back then. They are now back to about 86% again from four years in my Rv usage. I am very pleased with these batts for my operating style.)

Anyway, I can't quite figure out what those golf car guys actually use as a discharge rate per battery or whatever, since the 30 minutes a game doesn't seem to fit the 100 minutes minimum "my" shop uses.

Maybe for an all-day run? Three games at 30 min each is 90 minutes? Is three games a day reasonable? ( I am not a golfer)

[MEXICOWANDERER]

" Comparing apples to apples, has that definitely been proven in controlled studies between an equivalently built 3 cell (6V) deep cycle battery and a 6 cell (12V) deep cycle battery?"

Oooooo and dat's the rub.
There are no group 24 and group 27 batteries that have the .070" plate thickness of the most puny GC220.

Or any of the AGM batteries having anywhere near the plate thickness of the Lifeline.

Or larger batteries having .330" plate thickness of my Rolls cells.

And yes there are studies. For one, I conducted tests on Scrubber batteries. 6-cells.

They averaged 15% less cycle life, same brand heads up than GC220 batteries. Why? It came down to the % of electrolyte surplus in the Golf car batteries. Scrubber machines have an easier life style than golf car batteries. They get used for perhaps 4-6 hours then immediately get plugged in. Many golf course machines see three tours lasting a total of 12 hours daily. People who dress funny are hard on batteries.

This is why I chose 30" tall batteries. Tremendously thicker plates, the highest electrolyte plus percentage. Money is no object paste choice. Baby sat during greening, twice the man hours per amp hour for assembly and then finally, much larger sediment chambers. When I converted the electrolyte to Tropical Blend, I gave my choice the optimum survivability.

COST / LIFESPAN / PERFORMANCE / DURABILITY

A well-built GC-220 is perhaps the most competitively priced cyclable battery on the market. In a given environment it is easier to maintain, more forgivable and longer lived than a scrubber. But there's the rub - they have to see correct care and feeding to squeeze max kWh lifespan.

Also interesting study is the L16 versus the GC220.

Only engineers who study and record the effects of ablation and erosion are privy to some of this stuff.

[marcsbigfoot20b]

OldSmokey wrote:

All 3 of my batteries were bought in the same month....just adding them to the trailer permanently with some 1/0 cable.

not going to make much difference, 2-3 years max and you will be replacing them anyway..

Oldsmokey, still waiting to hear your reason why my brand new AGM batteries will only last 2-3 years?????

[marcsbigfoot20b]

OldSmokey wrote:

All 3 of my batteries were bought in the same month....just adding them to the trailer permanently with some 1/0 cable.

not going to make much difference, 2-3 years max and you will be replacing them anyway..

Really? Why would 3 brand new AGM batteries only last 3 years? Do tell.

[pnichols]

MEXICOWANDERER wrote:
Cutting to the chase...
The 3 cell battery offers more cycles and can take more abuse.

Comparing apples to apples, has that definitely been proven in controlled studies between an equivalently built 3 cell (6V) deep cycle battery and a 6 cell (12V) deep cycle battery?

.... Because even though each of two 230 amp hour 3 cell batteries's active electrodes have twice as much mass as that in each of two 115 amp hour 6 cell batteryies's active electrodes - the current density per unit of active electrode mass that the 3 cell battery must deal with is twice as much.

Hence, electrode life ("errosion or otherwise reduction") should be the same in each equivalent amp hour array - whether it be 3 cell or 6 cell. Of course, this is given that all other construction/design aspects are the same between the 3 cell (6V) deep cycle batteries and the 6 cell (12V) deep cycle batteries.

I see no electro-chemical reason(s) why cycle life can't be the same between a high quality 3 cell (6V) deep cycle lead acid battery array and a high quality 6 cell (12V) deep cycle lead acid battery array. It's just that the two battery types are shaped differently, so one or the other may fit better in any given RV's battery storage compartment.

[MEXICOWANDERER]

And yet...

A clinical specific analysis of wet GC vs AGM case-by-case may tilt the factor in favor of AGM. This is where an RV owner needs to use the stuff between the ears. Everything is a compromise. And everything can be biased with quantification.

I remember the shock on the owner's face when I recommended (4) 1105 Delco calcium calcium flooded (sealed) engine starting batteries for his dedicated inverter battery system. 950 CCA x (4) It was far too long a run from his L-16 bank to the inverter. An MCI conversion bus. 24 volt.