12v vs 6v

[ststefan]

What is the advantage if any of 2 6volt batteries over 2 12volt batteries? One would be hooked up in series and the other in parallel, but other than that what are the advantages of one or the other?

[Byron Kinnaman]

Originally Posted by ststefan

What is the advantage if any of 2 6volt batteries over 2 12volt batteries? One would be hooked up in series and the other in parallel, but other than that what are the advantages of one or the other?

2 12 Volt in parallel increase the available current/time by sum of rating on the two batteries.
2 6 volt in series you have the current/time rating of the lowest of the two batteries.

[madjack]

12v hooked in parallel must be bought at same time and be as "twin" as possible...if one goes bad, both will have to be replaced...WHY. ..because the stronger of the two will be in constant discharge into the weaker battery...PRO...if one goes bad, you will still have one to power your 12v systems and you can possibly get a set up with more amphours for your usage.........

Two 6v in series do not have the discharge problem, so, you don't have to be as concerned about twinning as with the 12s...if one goes bad, you will be stuck without 12v power.....

IMO, if you can afford the cost, weight, real estate and the twinning problems, two 12s are a better setup for heavy duty boony camping..if you will have power available on occasion, whether it be solar, gennie, campground or ???, a single 150ah 12v Trogan batt maybe a better choice......

You never actually stated your intended camping style...being specific will get more specific answers............

madjack

[Byron Kinnaman]

Originally Posted by madjack

12v hooked in parallel must be bought at same time and be as "twin" as possible...if one goes bad, both will have to be replaced...WHY. ..because the stronger of the two will be in constant discharge into the weaker battery...PRO...if one goes bad, you will still have one to power your 12v systems and you can possibly get a set up with more amphours for your usage.........

Two 6v in series do not have the discharge problem, so, you don't have to be as concerned about twinning as with the 12s...if one goes bad, you will be stuck without 12v power.....

IMO, if you can afford the cost, weight, real estate and the twinning problems, two 12s are a better setup for heavy duty boony camping..if you will have power available on occasion, whether it be solar, gennie, campground or ???, a single 150ah 12v Trogan batt maybe a better choice......

You never actually stated your intended camping style...being specific will get more specific answers............

madjack

The idea of batteries being "twins" is a myth. Even if one is smaller you'll still have the combination of the two Ah of usage available.

Many if not most people have a maximum of 2 weeks in the summer and a couple week-ends of camping. Some have a week-end every other year or less. Having large amounts of battery power just doesn't make sense to me.

We spend 90 to 100 days without hookups in the winter. We manage with a single "Marine" battery 74amph and a 65watt solar panel that's hidden away most of the time. I take it out and charge the battery every 3 or 4 day.

It can be done easily without huge expenses. I spent a whole lot less than the Honda generator set.

[Joe Romas]

Originally Posted by Byron Kinnaman

The idea of batteries being "twins" is a myth.

Maybe not.
Do a google search and you'll find the thinking is 50/50 and some that say it's not necessary throw in something like "it's so small it's not a problem".

They also add that when home seperate them and charge them seperatly.

But if you can find someone that owned a 1980's Oldsmobile diesel powered car ask them about it as they had two 12 volt batteries in parallel.
The common senarro was they replaced the bad battery and shortly the new battery was bad too.
They don't have to be twins but the weaker lesser voltage one will eventually take down the higher voltage stronger one.

[Byron Kinnaman]

Originally Posted by Joe Romas

Maybe not.
Do a google search and you'll find the thinking is 50/50 and some that say it's not necessary throw in something like "it's so small it's not a problem".

They also add that when home seperate them and charge them seperatly.

But if you can find someone that owned a 1980's Oldsmobile diesel powered car ask them about it as they had two 12 volt batteries in parallel.
The common senarro was they replaced the bad battery and shortly the new battery was bad too.
They don't have to be twins but the weaker lesser voltage one will eventually take down the higher voltage stronger one.

I know you read it on the internet so must be true.

[ststefan]

Thanks all. Most of my camping would be boondocking. I am thinking of getting a 90 watt solar panel. I am new to rv-ing and would like to gather as much info as possible. If my current battery and 90 watt solar is good enough I will stay with it. Otherwise I think I would go with the 2 12 volt batteries for the added benefit of still having 12 volts if one battery dies.

[Byron Kinnaman]

Originally Posted by ststefan

Thanks all. Most of my camping would be boondocking. I am thinking of getting a 90 watt solar panel. I am new to rv-ing and would like to gather as much info as possible. If my current battery and 90 watt solar is good enough I will stay with it. Otherwise I think I would go with the 2 12 volt batteries for the added benefit of still having 12 volts if one battery dies.

How long do you plan on camping at one time?

[ststefan]

Probably 4 to 5 days at a time

[Perryb67]

After this decision is made, the next question you need to ask/argue/answer is:
Flooded or AGM?

Enjoy,

Perry

[Joe Romas]

Originally Posted by Byron Kinnaman

I know you read it on the internet so must be true.

No that's a real myth

Sparky, what if a cell in one 12 volt battery shorted out, that can and does happen.
Then you would have a ten volt battery discharging a 12 volt battery

Go to a library and find some good textbooks an the subject.

[Franswa]

like they have a heart attack and...poooof...they're gone???

there can be a WHOLE LOT of factors that would influence one's decision of wether to go with two 12s or two 6s.....but the idea that one battery will suddenly DIE right at dinnertime and you will be marooned with NO power sounds a little funny to me.....

IME, other than a dead short and a battery exploding.....batteries die a really slow death....as in, you will notice that your batteries don't quite last as long as you sort of remember....a few outings like that and you will go to the trouble of testing your batteries at home and discover that, indeed, one of them is "dying" the slow death...(and if you had that exploding battery syndrome happen, having 12 volt power or not one night will be small on your preocupations list)

space, weight, your power consumption and how much solar recovery you can expect from your panel(s) are real considerations and worth investigating.....especially in a "smallish" trailer (add weight distribution to your planning)

the internet is flooded (pardon the pun) with opinions on the old "6 vs 12" issue.... while some opinions appear to be more credible than others there are plenty on both sides.....so the issue is really if one is better FOR YOU....(like you would probably not remove the back seat of your car to put in a 45 gal gas tank back there...even though it would mean longer range and savings given you'd only fill up where gas was cheaper)

on the solar panel front.... I like having X number of watts mounted flat on the roof....and half that amount of watts in a deployable panel stored inside trailer with extension cord... for a whole bunch or reasons

happy trails

[madjack]

...twinning...remember, it only applies to batteries connected in parallel...I have experienced this with those old Olds (Dad had two of those clunkers) and with 18 wheelers...a bad battery will draw the other(s) down...no doubt about it...just think about it...much as using a power bank to charge a cell phone or even a jump box on a car, when connected, they will charge up the down batt by drawing the "good" source down to where they are (or near abouts)........
...as to batts suddenly dieing...have you never had a vehicle, giving no indication of a problem and you go out and it is dead, whether it is sitting overnight in your driveway or in a store parking lot, even for a short stop..all I can say is I would love to live that charmed a life.......
...as in all things related to life, YMMV.............
madjack

[Mike Magee]

Originally Posted by Byron Kinnaman

I know you read it on the internet so must be true.

I read Byron's comment on the internet....

[squish]

We switched from two 12v group 24 deep cycle to two 6v golf cart batteries I forgot the group size but the foot print was within 1/4 inch of the G24, the 6 volt batteries are taller and much heavier.

They nearly doubled our usable available power.
We boondock and have an older BP branded 100w fixed solar panel.
This combo kept us in the green voltage wise for a week of camping under heavy tree cover.

It's been a great switch. It took some fiddling and some re working, and the system still isn't perfect. I want to change my solar charge controller, beef up the solar panel wiring right now its like 12 gauge thickness i would like to move down to about 8 gauge.

6volts can increase your storage capacity. It creates a deeper well so to speak because you are making one really big 12v battery. At least that's the simplified version.

[Franswa]

I never had the opportunity to compare (my trailer had two GCs in it when I got it) so it's nice to hear from somebody who's had experience with both options.

and BTW comparing battery life/use in a car and in a trailer is "apples to oranges"....I read that a starter in a small car will draw 50 amps at start up... the heaviest draw in a trailer will be less than a TENTH of that. That battery "dead" in your car at the shopping center, because you either left the lights on or haven't noticed hesitation at start up lately, would probably power your low demand items in your trailer for several hours.

You need a voltage meter.

[thrifty bill]

Also tempting is a lithium ion battery. They are expensive now, cost is surely going to slowly drop as production increases and more companies get into the business. Advantages include you can store it anywhere with no venting, you can use 100% of its capacity, it is small and light weight, and it will last longer (maybe.....). Disadvantage is cost of course.

No personal experience with these guys, but when my battery dies, I am going to give this strong consideration. Pretty much every major RV forum has a discussion or two or more on Lithium batteries. Its coming. May be too early to adopt, but later....

https://battlebornbatteries.com

[Franswa]

sorry couldn't resist.......but agree with you 100%....it'll be the norm in a decade or two....the advantages are too many....I've seen these battery packs offered in some RVs recently (Class Bs).

the last table on your battery site reminded me of this one....(I forget exactly where I found it and the details of the comparison)...the issue that seems to affect the cost difference greatly is the expected "cycle life"...wherever those came from (manufacturers?)

I've read that to maximize the number of cycles the battery bank should not be drawn down below 12.4V if possible....one more thing to include in "considerations" when designing a system....with the usual caveats: If it's going to cost you a thousand dollars to acheive that....you might as well just buy replacement batteries more often

with my set-up and power use now I can get to that goal in the summer....looking forward to the fall to see it that is still the case with the furnace in use (a bit in the evening and again in the morning)