2 6-volt or 2 12-volt batteries

[rbp111]

Granted, 2 6-volt golf cart batteries last longer than 2 12-volt batteries. But what if one of the 6-volt dies, are you with out all power until a new 6-volt battery is purchased?

Two neighbors of mine both are looking to purchase new batteries and the discussion came up about 6-volt versus 12-volt batteries with a third neighbor. All of us are true campers, going out into the USFS for example, where what you have with you is everything, as their is no power, water or sewer.

What do you think? Get 2 6-volt golf cart batteries or 2 12-volt batteries?

[time2roll]

^^^ Yes

[rbp111]

If I understand the prior memos, when you hook-up 2 batteries in series, in this case the 6 volt golf cart batteries, you would have approximatly 235 ah. When you hook-up 2 batteries in parrallel, in this case hooking up two 12 volt, you double the ah, thus getting 210, if the batteries are 105 ah each. Is that correct?

[wintersun]

If I had a vented compartment that would hold four flooded lead acid type batteries they would be 6v industrial true deep cycle ones. If one cell in one battery failed I would disconnect it and its partner battery from the bank and still have the 12v needed for the RV electronics (fridge, water pump, furnace control, lights). I could then wait until it was convenient to get the bad battery replaced or might decide to replace two or all four batteries.

With only two batteries and use out on the open road the better choice is two matched 12v batteries.

A common mistake made is to compare a FLAT battery performance and cost and longevity with an AGM battery. For RV use the AGM is not likely to last as long and it will cost twice as much up front.

FLAT batteries will handle partial discharge and partial recharge cycles better than AGM type batteries and this contributes to their longer life when used in an RV.

Less than 6v batteries in auto group sizes and larger are made to keep the weight of the battery manageable by the average human without need for a forklift or a hoist. Insustrial batteries come in voltage outputs as low as 2v and are commonly used for data centers, phone company switch installations, and cell towers.

[camperpaul]

Eurocamper wrote:

I guess that somewhere you can buy 12 volt deep cycle batteries with more than 100-105 Ah capacity, but I couldn't find any. On the other hand, there were plenty of 6 volt golf cart batteries with 225-235 Ahs to choose from. I figured I would go for the 235 Ah over the 210 Ah (2 x 105 Ah).

Not a huge difference, but an increase in capacity nonetheless.

There is one marketed by Interstate.
Approx 1000 AH
Weighs ~600 lbs.

I used them for UPS for Automatic Test Equipment. I could draw 10 Amps continuously for 48+ hours in the event of a power failure.

[Eurocamper]

12thgenusa wrote:

I am still wayne_tw wrote:
When using two 6 volt batteries wired in series, you double the volts but the amp hours remain the same.

When using two 12 volts wired in parallel, you double the amp hours but the volts remain the same.

Therefore, using two 12 volt batteries you will have greater capacity for the size of the battery bank than using two 6 volt batteries.

While the first two sentences are true, the third is not necessarily true. A 12-volt battery closest in size to a 6-volt GC2 has about 100 Ah. Two will give you 200 Ah. Two GC2s will give you 220 to 235 Ah at 20 hr rate.

That was my experience. I guess that somewhere you can buy 12 volt deep cycle batteries with more than 100-105 Ah capacity, but I couldn't find any. On the other hand, there were plenty of 6 volt golf cart batteries with 225-235 Ahs to choose from. I figured I would go for the 235 Ah over the 210 Ah (2 x 105 Ah).

Not a huge difference, but an increase in capacity nonetheless.

[wa8yxm]

VintageRacer wrote:
I look at 6 volt batteries as half a 12 volt battery in a more convenient package. I can lift a 6 volt 235 ah battery with one hand if it has a handle, lifting an 8D battery (12 volt deep cycle 235 ah) takes deep knee bends and a 5 minute warm up before or a chiropractor visit after... 🙂

Though I can and fairly easily lift and carry an 8-D the way I used to say it is this:

You take two Six Volt Golf car batteries, lug them to your RV and install you get 12 volt at 230 amp hours

you take 230 amp hours in a single package and attempt to lift and carry it to your RV you get..... A hernia.

Same concept as you posted.

Before my wife died I routinely loaded and unloaded a battery operated scooter, roughly 250 pounds.. By hand, no ramp.

[12thgenusa]

I am still wayne_tw wrote:
When using two 6 volt batteries wired in series, you double the volts but the amp hours remain the same.

When using two 12 volts wired in parallel, you double the amp hours but the volts remain the same.

Therefore, using two 12 volt batteries you will have greater capacity for the size of the battery bank than using two 6 volt batteries.

While the first two sentences are true, the third is not necessarily true. A 12-volt battery closest in size to a 6-volt GC2 has about 100 Ah. Two will give you 200 Ah. Two GC2s will give you 220 to 235 Ah at 20 hr rate.

[12thgenusa]

I second that.

[time2roll]

Get 4x GC2 :B

[hershey]

Go with the 6 volt batteries. Millions of golf carts can't be wrong.
Simple math...go with what works and lasts the longest. 6 Volt batteries.

[VintageRacer]

I look at 6 volt batteries as half a 12 volt battery in a more convenient package. I can lift a 6 volt 235 ah battery with one hand if it has a handle, lifting an 8D battery (12 volt deep cycle 235 ah) takes deep knee bends and a 5 minute warm up before or a chiropractor visit after... 🙂

All I say is start from what you need, not what batteries you want, and work backwards. first is how many AH at what voltage, second is how to get to that point. I personally use four 6 volt batteries in a 465 ah 24 volt configuration tied to two 12 volt 250 ah (each) start batteries. The starts back up the house batteries, the house batteries can back up the starts, and the generator has a separate start battery so I should be really upset if I ever really run out of power....

Brian

Brian

[Artum_Snowbird]

One of the best reasons for two 12's is a bit of a test. Disconnect one, and see how long you last. Now you will know pretty accurately how long two will take you.

With two sixes you will know when you run out.

[wa8yxm]

rbp111 wrote:
Granted, 2 6-volt golf cart batteries last longer than 2 12-volt batteries. But what if one of the 6-volt dies, are you with out all power until a new 6-volt battery is purchased?

Well, you have two bad assumptions in that one paragraph, I will cover.

2 6 volt last longer than 2 12 volt: Generallly that is true but while when we speak of six volt we are normally talking GC-2, 230 amp hour DEEP CYCLE (115 amp hours usable) (This is at the 20 hour rate).

When we talk about 12 volt there are dozens of different batteries, Many can be had in Deep Cycle if you are willing to look hard and pay through the nose. a pair of 8D 12 volt for example, will outlast that pair of 6 volt by a factor of over 2x, (Each 8D is about the same as the six volt pair all by itself, also as heavy as the six volt pair)


Second. There are no six volt batteries in an RV, only 12 volt, some of them come in two smaller halves for ease in handling and savings in price (Since the GC-2 is the single most produced lead acid rechargable the cost per unit is lower).

So though oney one of the six volt goes bad.. Actually usually only 1/3 of it goes bad.. But that is the same as if one cell in the 12 volt (1/6tgh of the 12 volt battery) went bad.. You replace 'em both.


Now to the 'Are you out of power' question: Depends. on shore power no, the converter will continue to convert.

If you are worried about, say the time it takes you to get to Sam's club from the campground.. No reason you can not put a small 12 volt (Say a Group 27) in parallel with the six volt pair. Some folks yammer about "The smaller/larger" battery chargin faster or slower and all sorts of dire warnings.. They should really research what they are saying.

(Fact, batteries in parallel, after the first charge/discharge cycle, are always in LOCK STEP when it comes to state of charge, if one of 'em is at 99, so is the other) Yes the larger battery will take a bigger share of the charge current (and provide a bigger share when powering the loads) but it's in perfect proportion to the size)

[Ron3rd]

I am still wayne_tw wrote:
When using two 6 volt batteries wired in series, you double the volts but the amp hours remain the same.

When using two 12 volts wired in parallel, you double the amp hours but the volts remain the same.

Therefore, using two 12 volt batteries you will have greater capacity for the size of the battery bank than using two 6 volt batteries.

I agree with Wayne for the most part. The advantage to true 6v golf cart batteries is the plates are thicker and can take more abuse with heavy discharging. Other than that volts are volts and amp hrs are amp hrs. Just my 2c.

Another point, if you do a cost analysis, two 6v golf cart batteries aint a bad proposition and IMO are a good long term value.