12V Battery Verse 2 6Volt - Page 2

oldtool2 · 03-18-2016, 09:11 AM

Quote:

Originally Posted by gljurczyk

One thing to remember if you put 2 6 volt in and one goes bad your just screwed where with 2 12 volt you would still have power...

I keep seeing this but its not right!

Replace a 12 volt with 2 6 volt, one six goes bad and you have no power, the 12 goes bad and guess what, you have no power, right? Same either way, a bad battery is a bad battery.

Now just add two 6's and you have two 6's and a 12 volt. A 6 volt goes bad and you still have the 12 volt to use, right? The 12 goes bad and you still have the two 6 volt ones to work off of.

dragon-roo · 03-18-2016, 09:28 AM

ok... NEED was maybe a bit strong but I did look at the ZAMP system and factory wiring on my Roo as I was excited not to have to do so much work! The ZAMP brand 120w panels at the dealership had 16 AWG wire, and the camper has 12 AWG and 14 AWG installed for most of the run. When I calculated the voltage drop, I was going to get around 12.9V at the batteries at the 3.2 amps the panel was capable of when the charge controller was putting out its maximum of 14.5v (which is too low anyway). That is barely enough to push anything into a flooded lead acid, and as the battery voltage rises the acceptance is going to drop off since you can't get the voltage any higher. A larger panel does not raise the voltage as the charge controller is still limiting the output voltage at the wrong end of the wire.

If you simply move the charge controller to near the battery, but still use most of the undersized wiring, you can almost double the amount of power you get into the batteries. You don't loose as much power from the same amount of voltage drop because you are feeding that long skinny wire with 18V at a lower current. Also the charge controller is now seeing the actual battery voltage. You need to upgrade the wire size to get the rest.

Spending $600 for a trickle charger... I would rather buy a small generator, but to each his own.

If you can be frugal with the power and eliminate some of those phantom loads, you may likely find that simply adding the second battery gives you enough extra capacity for how you want to camp, and you charge when you get home.

If you want help with the math of figuring out exactly what you need to meet what you want to do... drop me a PM. I would be happy to help.

oldtool2 · 03-18-2016, 09:30 AM

Quote:

Originally Posted by wicked1

I will dry camp maybe once per season for a few days, I will most likely stick with the one 12 volt battery and bring my charger so I can charge the 12v from my truck if I had to. I am not interested in dry camping especially if I head out to the Grand Canyon

Like you I rarely boondock. An occasional night at a road side rest just for an overnight stop to rest. I had a deep cycle from my electric motor from my boat so I put it in my 5er, along with a 1,000 watt full cycle inverter. I can charge my laptop, camera batteries or cell phone and watch tv during the evening. Get the weather and a good night sleep and take off come morning. If I can get the 5er level enough won't even unhook it. I probably don't need the second 12 volt but it was just sitting here so stuck it in.

By the time I get to my next stop, 5 or 6 hours away, the batteries are charged enough to do it again if I want to. When one goes bad I don't know if I will replace it or not.

Jim

dragon-roo · 03-18-2016, 09:34 AM

Quote:

Originally Posted by oldtool2

I keep seeing this but its not right!

Replace a 12 volt with 2 6 volt, one six goes bad and you have no power, the 12 goes bad and guess what, you have no power, right? Same either way, a bad battery is a bad battery.

Now just add two 6's and you have two 6's and a 12 volt. A 6 volt goes bad and you still have the 12 volt to use, right? The 12 goes bad and you still have the two 6 volt ones to work off of.

No... you would never want to mix the pair of sixes in parallel with the single 12v for more than a few minutes. You could swap back and forth between the two, but different capacity batteries in parallel will see one being a parasite of the other and almost always ruins at least one of the batteries.

Even with two 12v batteries in parallel you want to stick with same size batteries. Some even go so far as to say you need batteries from the same batch, but 'my' real world experience so far has been that you don't need to get THAT crazy.

oldtool2 · 03-18-2016, 09:53 AM

Quote:
Originally Posted by gljurczyk
One thing to remember if you put 2 6 volt in and one goes bad your just screwed where with 2 12 volt you would still have power...

I keep seeing this but its not right!

Replace a 12 volt with 2 6 volt, one six goes bad and you have no power, the 12 goes bad and guess what, you have no power, right? Same either way, a bad battery is a bad battery.

Now just add two 6's and you have two 6's and a 12 volt. A 6 volt goes bad and you still have the 12 volt to use, right? The 12 goes bad and you still have the two 6 volt ones to work off of.

__________________

Quote:

Originally Posted by dragon-roo

No... you would never want to mix the pair of sixes in parallel with the single 12v for more than a few minutes. You could swap back and forth between the two, but different capacity batteries in parallel will see one being a parasite of the other and almost always ruins at least one of the batteries.

Even with two 12v batteries in parallel you want to stick with same size batteries. Some even go so far as to say you need batteries from the same batch, but 'my' real world experience so far has been that you don't need to get THAT crazy.

I don't care how you wire them. I didn't say to hook the sixes in parallel. My point is if you lose a six you still have the twelve to work from so you don't lose everything, as was implied by gljurczyk .
.

Jim

ChateauV10 · 03-18-2016, 10:07 AM

Small point about going from 2 group 24s to two golf cart 6 volts...they have the same footprint, so they fit in the same place. they are a little taller, so the tops of the battery boxes might not fit perfectly, but put the strap around the box and you are good to go.
Group 31's are larger, need bigger boxes and often do not fit the space on a trailer tongue without modifications. I can buy GC-2s at Walmart and Costco at very competitive prices, so that is the way to go for me.

I run 2 group 24s normally and switch them out for two GC-2 when I will be dry camping for a week-end. if I am paranoid, I'll bring a group 27 along that I normally use for a trolling motor. That way, I have a back up if I need it. (I'm a belt and suspenders kind of guy in some areas...)

My idea is to go camping with a minimum of fuss, be comfortable, not make a bunch of noise (generator) or spend a lot of time setting things up...

Have fun!

SeaDog · 03-18-2016, 10:21 AM

Most have answered your questions so here is my 2 cents. If you always hook up at camp sits or where ever save your money and go with what you have. With maybe in the feature adding one 12V for that 2 day or so dry camping JMHO

dragon-roo · 03-18-2016, 10:29 AM

I really liked the two GC-2s that I had in the popup. I would have went with 4 of them on the Roo, but they just didn't fit the space and needs as well, this time. It would have given me more capacity than the 3 group 31 AGMs too. You sure can't beat the price/AH on those GC2 though!

pmsherman · 03-18-2016, 09:35 PM

Quote:

Originally Posted by oldtool2

I keep seeing this but its not right!

Replace a 12 volt with 2 6 volt, one six goes bad and you have no power, the 12 goes bad and guess what, you have no power, right? Same either way, a bad battery is a bad battery.

Now just add two 6's and you have two 6's and a 12 volt. A 6 volt goes bad and you still have the 12 volt to use, right? The 12 goes bad and you still have the two 6 volt ones to work off of.

I've seen this argument of using two 12V in parallel vs two 6V in series and question the wisdom of the statement "if one 12V goes bad, you still have the other one."

From a technical standpoint that statement is true but from a practical standpoint, it may not be. If one of a pair of 12V batteries fails in service, it will probably have a shorted cell (maybe more than one shorted cell) caused by deposit buildup on the bottom of the battery. Once this happens, the bad battery will immediately discharge the remaining good battery and you'll end up with one shot battery and one fully discharged battery. If you don't figure out which one is bad and recharge the remaining good one within a few hours, keeping it in its discharged state will most likely permanently damage the good battery.

Assuming you've saved the good battery, it's probably as old as the failed one. Do you want to replace one battery and have a new one and an old one in parallel? I wouldn't want to do that.

12V deep cycle batteries in the $100 price range are almost always "marine" batteries that are hybrids, not true starting batteries and not true deep cycle batteries. 6V golf cart batteries are solid plate units, true deep cycle batteries, much more capable of surviving discharges to less than 50% of capacity than hybrids. The don't have the CCA rating of hybrids or auto starting batteries but are designed to survive sustained lower current drains to a deeper discharged state.

The reserve capacity of a hybrid marine battery is determined by draining it with a 25A load. Golf cart batteries reserve capacity is determined using a 75A load. When comparing batteries, don't forget to account for this difference in testing procedures.

Replacement wet cell lead acid batteries are available from big box and auto parts stores all over the country. I'd have no concern about two 6V series connected batteries being less reliable than two 12V ones in parallel. If one fails in either case, both will probably be replaced and if I'm travelling, it'll probably be less than two hours travel from where I am.

I also carry a 12V 100AH battery for hobby use. This could be used as an emergency replacement for the house batteries in my Georgetown if absolutely necessary.

Phil

dragon-roo · 03-18-2016, 10:57 PM

Great points pmsherman!

Now perhaps a more simple point that is just as important... statistically speaking the lifecycle of a marine battery is far lower than that of the 6v batteries. You are far more likely to experience a sudden failure with them.

The marine batteries also statistically tend to fail in the modes of one or more shorted cells, or one or more open cells from what I have read. Experience in our boat would seem to back that up. All of the reading I have done (and my limited experience with them) seems to point to much more gradual failure modes for the 6v. Unless you do something like run them dry, they tend to just slowly loose capacity.

I went through 2 group 27 marines in 3 years when we started camping. I got 7 years from my first set of golf cart batteries for the popup. I didn't have a charger that would attempt to desulfate at the time and they were not holding as much capacity as I was comfortable with so I figured they didn't owe me anything after 7 years. The second set were still in service when I sold the camper to my sister last year.

Of course now that I say that, I will have a 6v blow up on me or something

WolfWhistle · 03-19-2016, 06:33 AM

DR, your last sentence... I overheard the lady I worked with in a conversation; she had another battery failure... second one in about 5 years. I had to think, but realized that my 2002 Chevy still had the original Delco battery (this happened in 2009), so I mentioned that fact. You know the very next morning, my truck wouldn't start... dead cell. I know this was coincidence, but amazing none the less.
WW

oldtool2 · 03-19-2016, 10:36 AM

Quote:

Originally Posted by pmsherman

I've seen this argument of using two 12V in parallel vs two 6V in series and question the wisdom of the statement "if one 12V goes bad, you still have the other one."

From a technical standpoint that statement is true but from a practical standpoint, it may not be. If one of a pair of 12V batteries fails in service, it will probably have a shorted cell (maybe more than one shorted cell) caused by deposit buildup on the bottom of the battery. Once this happens, the bad battery will immediately discharge the remaining good battery and you'll end up with one shot battery and one fully discharged battery. If you don't figure out which one is bad and recharge the remaining good one within a few hours, keeping it in its discharged state will most likely permanently damage the good battery.

Assuming you've saved the good battery, it's probably as old as the failed one. Do you want to replace one battery and have a new one and an old one in parallel? I wouldn't want to do that.

12V deep cycle batteries in the $100 price range are almost always "marine" batteries that are hybrids, not true starting batteries and not true deep cycle batteries. 6V golf cart batteries are solid plate units, true deep cycle batteries, much more capable of surviving discharges to less than 50% of capacity than hybrids. The don't have the CCA rating of hybrids or auto starting batteries but are designed to survive sustained lower current drains to a deeper discharged state.

The reserve capacity of a hybrid marine battery is determined by draining it with a 25A load. Golf cart batteries reserve capacity is determined using a 75A load. When comparing batteries, don't forget to account for this difference in testing procedures.

Replacement wet cell lead acid batteries are available from big box and auto parts stores all over the country. I'd have no concern about two 6V series connected batteries being less reliable than two 12V ones in parallel. If one fails in either case, both will probably be replaced and if I'm travelling, it'll probably be less than two hours travel from where I am.

I also carry a 12V 100AH battery for hobby use. This could be used as an emergency replacement for the house batteries in my Georgetown if absolutely necessary.

Phil

Phil,

There is a lot of truth in what you have written.

It is just the basic statement "if one 12V goes bad, you still have the other one." That gets to me. I guess I am just nit picking. I picked up a few screws a while back in on of my truck tires. They destroyed that tire. It was less than a year old but I guess I should have replaced all the tires because it was going to happen to all of them. Anything is possible.

When I need to replace my batteries I will probably go with four 6 volt gc batteries. I will run one pair and when they get low switch to the other pair. With the load I have they should last me "forever". For now I am running a 12 volt deep cycle and a 12 volt agm battery. This is only because this is what I had available. So far no problems but not what I would recommend, LOL!

Now which one is going to go bad next weekend?

Jim

Manion · 03-22-2016, 10:43 PM

I added a second group 24 12v at purchase. I'm pretty happy with that.

2015 Shamrock 23IKSS
2004 Chevy Silverado 2500HD 4X4 Duramax
Sent from my iPhone using Forest River Forums

Witch Doctor · 03-23-2016, 03:54 AM

Quote:

Originally Posted by Manion

I added a second group 24 12v at purchase. I'm pretty happy with that.

2015 Shamrock 23IKSS
2004 Chevy Silverado 2500HD 4X4 Duramax
Sent from my iPhone using Forest River Forums

X'2, I have never had a problem, but I really wouldn't call myself a Boondocker...

**bikendan** · 03-23-2016, 06:14 AM

Quote:

Originally Posted by Manion

I added a second group 24 12v at purchase. I'm pretty happy with that.

2015 Shamrock 23IKSS
2004 Chevy Silverado 2500HD 4X4 Duramax
Sent from my iPhone using Forest River Forums

I've been using two 12v deep cycle batteries for almost 10 years now and along with my Honda 2000i and a 400w inverter, we have had no problems dry camping.
If not for clearance issues, I'd have two 6v golf cart batteries.

Tom48 · 03-23-2016, 11:34 AM

Quote:

Originally Posted by dragon-roo

No... you would never want to mix the pair of sixes in parallel with the single 12v for more than a few minutes. You could swap back and forth between the two, but different capacity batteries in parallel will see one being a parasite of the other and almost always ruins at least one of the batteries.

Even with two 12v batteries in parallel you want to stick with same size batteries. Some even go so far as to say you need batteries from the same batch, but 'my' real world experience so far has been that you don't need to get THAT crazy.

I concur. Mismatched sets will run you down to the performance of the lowest, weakest battery. A bad cell in one 6 volt may leave you stuck, but a bad cell in one 12 volt in parallel with the other 12 volt will likely have killed both 12 volts before you catch it. In our F-250 diesel one of two batteries went bad. FORD authorized replacement of both for the above reasoning since starting voltage is critical to our electronic starting system.
Even when we ran the third Group 24 sized battery in the TH, it was newer and different from the two mains, so I segregated it by a switch, so that it did not charge and discharge repeatedly with the two main batteries. WE kept it in reserve IN CASE we ran things down too far dry camping. The blessing is that our basic 200 watt solar panels and PWM charger that someone referred to as a trickle charger keep the two mains at a safe usable level in almost every case, without having to think about it at all. So I would say, not to worry about a PERFECT solar charging system, but get 100 watts or more on the roof so you never even have to worry about the batteries in storage and almost never have to think about them while camping.

wicked1 · 03-24-2016, 10:38 AM

One thing never to go cheap on and it has its value in an RV and vehicle is a good battery changed every 5 years.

Also maintenance or constantly monitoring it pays off plain and simple

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