12v vs 6v battery question

SoundGuy wrote:
simply using 12 volt batteries sequentially is my own personal choice whether you like it or not

babock wrote:
LOL...but you are the one telling everybody that to keep the bad battery in parallel from bringing the other one down is to operate them sequentially. Operating batteries sequentially is a big pain unless you hardly ever boondock.

LOL indeed, "operating batteries sequentially" is as easy as turning a switch from one battery to another ... apparently you find that "a big pain"? :h :W

Don't get your panties in such a bunch when someone disagrees with you.

Sorry, can't oblige ... don't wear panties. :W That aside, I don't really care what anyone else does, just pointing out that because it's such a simple matter to run one 12 volt battery until it's depleted to 50% DOD then replace it with another, which can't be done with dual 6 volts running in series, that's what some of us choose to do. Whether you agree or not is irrelevant. :R

I keep hearing about the huge problem of a 6V GC battery dying and leaving the TT without power, which obviously can't happen with two 12V batteries.

Yet, I don't read many posts on this forum or any other forum complaining about a 6V GC battery suddenly failing. Do they eventually go bad? Sure, but you get the sense of that by observing they do not hold a charge a long as they did when new, or almost new.

As I've written before, is it possible a 6V GC battery can fail without warning? Yes. Is it probable? No. Is it possible someone could slam into my TT, totaling it, while I'm stopped at a red light? Yes. Is it probable? Probably not, but the odds are certainly greater than a 6V battery failing without notice.

For simplicity - I carry 2 -12 v battery's - one goes down i switch. But i have ran a separate charge line from my TV to my RV battery, through a 30 a circuit breaker. I do the same with my LP tanks.One goes I change. battery discussion seem to get out of hand - so I try to stay away from them.I to am a Elec. Eng, plus unlimited master electrician ship & shore.I also do not argue about electricity. Have fun.

I really appreciate all the info, I went with the 6v golf cart batteries. For me they seem like the best option for my camping style.

Good deal, at least you could wrangle through the tangents of discussions that typically happen when battery power is discussed.

A lot of 6V vs 12V theorizing revolves around the failure of one 6V in a series connected pair. If one 6V failed so that it would not provide power to the 12V circuit, an owner would be out of luck. I think the apprehension is caused by owners of 12V batteries that have seen their batteries fail and assume a 6V jar would do the same. At one time, as a golf course mechanic, I serviced 360+ 6V batteries in golf carts. Even with the most terrible misuse and bad charging routines, I never saw one battery fail so that an individual cell did not pass any power within the battery.

SoundGuy wrote:
simply using 12 volt batteries sequentially is my own personal choice whether you like it or not

LOL...but you are the one telling everybody that to keep the bad battery in parallel from bringing the other one down is to operate them sequentially. Operating batteries sequentially is a big pain unless you hardly ever boondock.

Don't get your panties in such a bunch when someone disagrees with you.

I think we need to look at this in a more practical way. As a reminder from my OP, I don't boondock, I use the batteries mainly to keep my Resi fridge while traveling.

Here are a couple of things that apply in most cases.

Realistically most people don't want to fool with checking their batteries to see when it is time to switch from battery to the other. We camp to get out and hike, bike etc, not to mess with batteries. I know some people really get into seeing how they can get the most out of their batteries for boondocking, and if you enjoy that, great, but the majority want simplicity.

I can see the redundancy of running sequential, but redundancy is not critical to most on a camper. On an airplane where if a battery failed I might fall out of the sky, I want redundancy. On my camper if a battery fails, I have to run my slide in with a ratchet, and my ice cream melts. I can probably survive this.

Most of the time a battery gives you some warning that it is going bad, and you lose capacity overtime, not a failure where it just dies, but again if it does just die, I'm not falling from the sky.

Also you need to think about pros/cons, and availability of the 3 types of batteries that have been discussed, and the info I've learned from this post.

1, common 12v "deep cycles" are the easiest to find, and fairly cheap, but don't have great capacity, and don't seem to be as durable over a couple of years.

2. Golf cart 6v batteries are fairly common, probably more common in my area since I'm 5 miles from a city with probably 10,000 golf carts. They tend to last longer capacity wise, and are more durable, and can withstand deeper discharges. Also they were only $5 a battery more than the cheap 12v deep cycles.

3. True deep cycle 12v, harder to find, but built more like a golf cart battery. Sounds like they are more expensive.

Where I live and camp in the southeast, I can't think of many places where I'd be more than 20 miles from a Walmart, or a auto parts store where I could buy a battery in a pinch.

I really appreciate all the info, I went with the 6v golf cart batteries. For me they seem like the best option for my camping style.

babock wrote:
Please enlighten us how you manage your "sequential" discharge and charging of your batteries over a 4 day boondocking camping trip.

I don't have to "enlighten" you on anything, simply using 12 volt batteries sequentially is my own personal choice whether you like it or not, just as I also use my propane tanks sequentially, again whether you or anyone else may approve or not. There is no need in either case to run parallel if one chooses not to ... and in the case of the batteries, running them sequentially obviates any potential failure of one having any affect at all on any other batteries one may have. Doesn't take a degree in rocket science to understand this simple concept - duh. :S

SoundGuy wrote:
Seriously? :h So simply switching from one battery to the other using the battery disconnect switch is too difficult for you? LOL indeed! :B

So..basically, you have 2 batteries that end up with different discharge cycles on them that are no longer even close to being matched. So..what happens when you run your heater during the night and need to switch from one to the other once the one battery gets down to 50% discharge? You really wake up, measure the voltage and switch the batteries?

As far as charging, how do you even end up charging them evenly?

You must love the battery switching game.

Please enlighten us how you manage your "sequential" discharge and charging of your batteries over a 4 day boondocking camping trip.

SoundGuy wrote:
To repeat AGAIN :S - impossible if you run those 12 volt jugs sequentially.

babock wrote:
LOL....so you are going to operate until one runs down to 50% and then switch to the other? What a pain in the a$$!

Seriously? :h So simply switching from one battery to the other using the battery disconnect switch is too difficult for you? LOL indeed! :B

You have the additional issue of switching them so that are both in parallel to charge them.

Why would two 12 volt batteries have to be charged together? Answer - they don't. Clearly you haven't thought this out. :R

SoundGuy wrote:

babock wrote:
The difference in internal resistance between 2 6V in series and 2 12V in parallel is negligible assuming the overall capacity is the same.

It's as easy test to do. Take both types and put a constant load on them and measure what the voltage drops from a fully charged battery.

Therefore, not a reason to choose 12V over 6V batteries.

Prove it ... as I can clearly prove otherwise. ;)

As this article clearly proves 12 volt jug internal resistance IS considerable lower and therefore suffer less voltage drop under heavy inverter load than a similarly rated pair of 6 volt jugs. Hard to argue with facts. :Z

sadly the author is not comparing apples to apples.. his comparison is that of two deep cycle golf cart batteries vs an SLI battery.. of course the 12V battery wins.. it's designed to discharge at high current, the golf cart batteries are not..
the intended use is different. the author is full of chit.