Switching To 6 Volt

[jplante4]

I'm planning on switching the house side of the Sahara over to 4 - 6 volts golf cart batteries this spring. Either T-105s or Interstate. I'm also planning on adding another 100 watts of solar to the 100 I already have and a new solar controller. I'm trying to get set up for some short stay dry camping.

I currently have 4 12 volt Napa "deep cycle" marine/RV battries that I'm estimating at about 200 AH for all 4. The new arrangement should get me to around 800 AH.

The Sahara has a 120 watt isolator. Will I need to beef that up as well? What else do I need to consider?

Jerry

Edit: This is something I'm planning to do myself.

[jplante4]

Just as a follow up, I had the local RV shop install another 100 watts of solar and 4 - 6 volt Interstate GC2 house batteries. The chassis batteries were acting up as well, and I suspect that something on the un-switched chassis side is on. I looked at the usual suspects (basement lights, heated mirrors, backup camera) but nothing was on. So they're load testing the chassis batteries and replacing them with Grp 31 AGMs if necessary.

I'll post pics of the install when it's done. I had the shop do this because they could get it in this week. I hate having to pay for something I can do myself, but I really don't have anywhere to work on the coach myself.

[wa8yxm]

jplante4 wrote:
I currently have 4 12 volt Napa "deep cycle" marine/RV battries that I'm estimating at about 200 AH for all 4. The new arrangement should get me to around 800 AH.

Some bad math.. About the smallest 12 volt MARINE/deep cycle is the Group 24, and those run 70-75 AH each so you are looking at at least 300 AH now.

WHen you switch from one-piece 12 volt batteries to 2-piece 12 volt batteries ()
(6V)+(6V)=12V
You add voltage, not current
Your T-105's are what \215 AH, so two pair would be 430 AH.

Just so you know. (you do add the two pairs, but one each pair you only add voltage, not amp hours).

Beyond that correction I have no comment.. It is an upgrade, and also the fact that the T-105 is a True DEEP CYCLE, not a "MARINE" adds to the usable capacity I might add, also to the overall life of the batteries if properly cared for.

[RJsfishin]

I can't believe some of you experienced guys can make battery capacity so dam difficult.

First of all, basically there in no difference in amp hour capacity between 6v & 12v. The physical size and weight of a battery determines it's AH capacity.

Therefore, if you figure that each typical RV deep cycle battery, whether 6 or 12v, contains approx. 100 AHs capacity, then it is all very simple, correct ??
But we know that the skimpy group 24 12v batteries are smaller, therefore have some less capacity. But they are not the typical RV battery either, so just forget them, ok !!
All gp 27 12v batts contain between 90 and 115 amp hours.
All typical 6v GC batts contain between 200 and 220 amp hours.

So any way you slice it, 4 typical deep cycle RV batts, 6v or 12v, are going to give you on average of about 400 amp hours, excluding those skimpy little 24's

Now if we want to get all teckie over each single amp hour, then lets start a different thread, and really get down to the nitty gritty,......but really, who cares,.....is it worth haggling over ?

I'd like to think this clarifies the subject of AH capacity just a little.

[MrWizard]

I've had 6v , 12v car jars, and 12v Telco server AGM batteries
The AGM have been the best by far

Four group 24 marine batteries total approx 300 amp hrs
Of which 150 is usable on a repeated basis
It is not good to take most batteries below 50%
On a repeated basis, once a year with an immediate full recharge, but not every use cycle

[2oldman]

jplante4 wrote:
I may just say screw it and do 12V AGMs and stop carrying around distilled water.

Do that.

[jplante4]

BPRescue wrote:

jplante4 wrote:


I currently have 4 12 volt Napa "deep cycle" marine/RV batteries that I'm estimating at about 200 AH for all 4. The new arrangement should get me to around 800 AH.

.

There is no chance your 12V Deep Cycles are rated at 50AH each. Cranking battery; maybe, but not a Marine/Deep Cycle. You should look up the specs. Either way, DO stay with Deep Cycle

Also, 800 is way off via 4 = 12V, or 4 = 6V. With a 4 battery setup, you will be closer to 450AH regardless which direction you go.

Yeah I looked these batteries up when I bought the coach and all I got was 105 CCA, which is why I put deep cycle in quotes. They're shot anyway, I think the current solar charger is cooking them.

[jplante4]

wolfe10 wrote:
Correct. Four 6 VDC "regular" golf cart batteries wired in series/parallel will give you around 440 amps @ 12 VDC.

The main issue is "what are your electrical needs"? Extended dry camping without running the generator with heavy electrical consumption OR occasional dry camping with lesser consumption?

Thanx Brett. With our current setup, we're pretty much limited to FHU camping (an oxymoron for sure). I'd like to be able to hit a state or national park that isn't FHU and be limited by holding tank capacity rather than electrics, running the genny once or twice a day. So I guess 4 days would be the max stay.

I have a Xantrex 2000 W inverter/converter in there now (can't remember the model number) and it does have settings for battery type. I also have a Magnum sitting in the basement that I can swap out if need be.

[wolfe10]

Correct. Four 6 VDC "regular" golf cart batteries wired in series/parallel will give you around 440 amps @ 12 VDC.

The main issue is "what are your electrical needs"? Extended dry camping without running the generator with heavy electrical consumption OR occasional dry camping with lesser consumption?

[BPRescue]

jplante4 wrote:


I currently have 4 12 volt Napa "deep cycle" marine/RV batteries that I'm estimating at about 200 AH for all 4. The new arrangement should get me to around 800 AH.

.

There is no chance your 12V Deep Cycles are rated at 50AH each. Cranking battery; maybe, but not a Marine/Deep Cycle. You should look up the specs. Either way, DO stay with Deep Cycle

Also, 800 is way off via 4 = 12V, or 4 = 6V. With a 4 battery setup, you will be closer to 450AH regardless which direction you go.

[RoyB]

Sometimes you can find a spec sheet for your proposed battery...

I usually keep a copy around for the Trojan batteries and if you can match up the battery weights the specs will be around the same.

TROJAN SPECIFICATION GUIDE

Batteries in parallel you can combine their AH's but DC Voltage stays the same...

Batteries in series you add the DC voltage but the AH's stays the same...

In order to increase the AH's and DC voltage of the 6 VOLT batteries you have to have two parallel groups of 6V batteries in series...

I suspect your GP27 12V Trojans are around 100AH capacity - try to match them up from the chart above...

The 6V batteries with the very large core give alot of grunt power... Check from the chart how long the batteries will operate drawing certain amps load.

Roy Ken

[SoundGuy]

jplante4 wrote:
If I'm following the math, I'm really not adding that much capacity switching to 6v, so I may just say screw it and do 12V AGMs and stop carrying around distilled water.

Well if you currently have G27s they're each likely rated at ~ 90 AH apiece for a total of ~ 360 AH at the 20 Hr rate for four of them connected in parallel. Sure, you can say "screw it" and opt for more costly AGMs but for the investment you're going to have to put out you darned well better make sure you can properly recharge them, particularly when you're not using solar but rather a 120 vac converter / charger to maintain them. Many AGMs require temperature compensated charging which almost no converter installed in trailers these days is capable of, otherwise you'll be replacing the much sooner than you expect. :M The devil is in the details. 😉

[CA_Traveler]

There are posts about 6V AGMs available from Sams Club. But research AGM charging profiles first as they are not the same as flooded.

[BFL13]

"2 sets of 6 volt 225 AH batteries in series/parallel = 450 AH at 6V?"

Nope. 450AH at 12v.

Suggest reading this before you do anything-- 🙂

http://www.bestconverter.com/Books_c_67.html

[jplante4]

SoundGuy wrote:

jplante4 wrote:
Edit: This is something I'm planning to do myself.

Perhaps you shouldn't considering you don't seem to grasp the basic math involved here. 😉 With a single battery or two and a small solar panel, say 100 watts, installation is pretty elemental but once you start upgrading to a bank of batteries, a significantly sized solar panel system, a suitably sized controller, and wiring suitable for the task you really need to understand exactly what it is you're doing and why, otherwise you could end up wasting a lot of $$$$ on a system that doesn't achieve what you expect it will. 😞

Yeah I hear ya, but the local shop charges $140 per hour shop rate and they're notoriously slow. If I wanted them top do this, I would have needed to get into the queue last November. There are plenty of YouTube videos by people who have done this. In addition to all this stuff, I need to clean up, paint and lube the battery tray, and seeing that the chassis batteries were replaced at the same time as the house batteries, I might as well do them while their out.

I was really just curious about the isolator and if I could get by with the one I have. I already have "a bank of batteries", just 12 V instead of 6. If I'm following the math, I'm really not adding that much capacity switching to 6v, so I may just say screw it and do 12V AGMs and stop carrying around distilled water.