Single AGM or 2 GC2???????

[HTElectrical]

I thought I would get a couple opinions on which way I should go for my Battery replacement strategy this time.
A little background:
I just replaced my converter with a Progressive Dynamics Inteli-Power Converter 9200-14.8 Volt Deck Mount.
I had a pair of Costco GC2 Battts that were put into service on 2/2013, but were abused by my crappy WFCO converter. When I boondock, I always run my Honda 2000 (with 5 gal. external tank) basically 24/7 while I'm at the Dunes, and if not out in the sand I have power available at my covered parking. Trailer is always in the higher temps of west coast (Las Vegas, Desert)
Just recently one of my GC2s developed a shorted cell, so I need to either replace those with new 6V, or possibly with a single 12v AGM. Since I never really run my inverter or 12v for any length of time without plugging in what would be the the most economical, trouble free, dependable way to go?


Thanks in advance!!!!!!!


Costco GC2 batts are $86.00ea so a pair would be about $187.00.

[harold1946]

Sam Spade wrote:

HTElectrical wrote:

Probably 2 Costco GC2 batts again. Correct???

I have a charge wizard, but since I only slightly discharge them, the only reason to use the Wiz, is to boil of the Sulfation that I cause.

Despite the quoted opinion, I think AGMs are always a better choice unless your budget is REALLY tight.

Given the usage pattern your describe, one large 12 V "deep cycle" AGM probably can be had for about the same price as replacing the two that you presently have.
No need to add water, virtually no sulphation and no corrosive gasses escaping to corrode things nearby.

All wet cell batteries are subject to sulfating, including AGMs.

[pianotuna]

Hi Mex,


Very nice post--thanks for sharing your knowledge with us.

[MEXICOWANDERER]

I hesitated writing this as I feel strongly it would be a waste of time.

Professionals compensate for abnormally high ambient temperature by adjusting the specific gravity of cell electrolyte.

Adjustment means less dense specific gravity. More water less acid. A higher percentage of water.

In this case I would recommend a final specific gravity of 1.260
Equal to a .025 reduction in density
Means a fully charged battery measured with a hydrometer will be 1.260

DRAWBACKS

• Cell electrolyte must be diluted with distilled water
• All cells MUST be equal in density
• The best way to do this is to wear gloves and googles
• Carefully empty all six cells into a plastic vessel
• Five gallons capacity would be ideal
• Measure specific gravity as it sits
• Start adding distilled water
• A BIT AT A TIME
• Stir thoroughly after each tweak with water
• Measure gravity after EACH addition of distilled water
• Slowly but surely dilute the electrolyte to 1.260
• If you bumble and gravity ends up at 1.258 don't sweat it

What's left in the plastic container is HAZARDOUS WASTE. Seal it tight. Many battery places will accept it because it is stated as being BRAND NEW ELECTROLYTE.


ADVANTAGES

• At temperatures of 90F adjusted density will maintain same spec performance as the battery did with original acid at 68F
• Battery life is at the very least DOUBLED (expect 250%) at elevated temperatures
• The advantage increases as the temperature exceeds 100F to 110F
• The battery can be "more safely" charged at extreme temperature.
  
  SAFETY FIRST! Please do not even think about doing this without using goggles and plastic gloves.
  
  

Gassing, corrosion is dramatically reduced in lieu of reducing charging voltages. However to make this perfectly clear HOT acid eats plates regardless of voltage. Only weakening the potency of acid reduces plate corrosion to "normal" amounts.

A battery DISTRIBUTOR such as the regional INTERSTATE battery distributor may or may not be willing to do this for a price. Only you can decide whether or not 250% increase in battery life justifies the hassle or labor cost.

Professionals label this adjustment as being TROPICAL BLEND ELECTROLYTE

[Sam_Spade]

wa8yxm wrote:

What's more AGM's are SEALED Valve Regulated Lead Acid. Adding distilled is NOT an option Thus the total life tends to be less than with Flooded types.

That is exactly the OPPOSITE of everything I've read, heard and experienced with AGMs. Which is that they typically have a useful life TWICE as long in most practical applications.

Could you please provide some reference for the claim "total life tends to be less" ??

[DiskDoctr]

HTElectrical wrote:
$184.00 for 2 GC2s. Done. Thanks for everyone's help.

That sounds like a good choice. I'd suggest installing them and then plugging in your converter for 2-3 days before you go. Get them fully charged and ready to go.

Enjoy your trip!

[theoldwizard1]

Dusty R wrote:

It appears that you are not running on battery very much you don't need much storage. So why have 2 batteries?

I am not a fan of the marine/dual purpose batteries. I don't think they do either job well.

Duracell (made by East Penn, sold at Sam's club) does make a 12V deep cycle golf cart battery (size GC12). Your local Sam's Club may not have it in stock, but they can get one for you. The problem is, it costs MORE than TWO GC2 which store more energy.

[Atlee]

And how many times has someone actually reported on here one of their 6V GC batteries died without warning?


Not saying there haven't been one, but I don't remember.

The fact remains that you are more likely to have someone rear end your trailer and total it while at a stoplight than you are to have one of two 6V GC batteries fail without warning.

marcsbigfoot20b27 wrote:

HTElectrical wrote:
I thought I would get a couple opinions on which way I should go for my Battery replacement strategy this time.
A little background:
I just replaced my converter with a Progressive Dynamics Inteli-Power Converter 9200-14.8 Volt Deck Mount.
I had a pair of Costco GC2 Battts that were put into service on 2/2013, but were abused by my crappy WFCO converter. When I boondock, I always run my Honda 2000 (with 5 gal. external tank) basically 24/7 while I'm at the Dunes, and if not out in the sand I have power available at my covered parking. Trailer is always in the higher temps of west coast (Las Vegas, Desert)
Just recently one of my GC2s developed a shorted cell, so I need to either replace those with new 6V, or possibly with a single 12v AGM. Since I never really run my inverter or 12v for any length of time without plugging in what would be the the most economical, trouble free, dependable way to go?


Thanks in advance!!!!!!!


Costco GC2 batts are $86.00ea so a pair would be about $187.00.

According to many, having one bad GC2 in a pair is nearly impossible. :R
I would go 12 volt flooded on the cheap or 12 volt AGM if you have a few bucks.

[HTElectrical]

$184.00 for 2 GC2s. Done. Thanks for everyone's help.

[wa8yxm]

Some math
The Costco GC-2's are what about 80-100 bucks a pop 220 Amp Hours give or take a few at the 20 hour rate.

AGM's are way more expensive. Even "Blems" can be well over 150 dollars

Group 24 75 AH (Fit the same tray)
Group 27 95-100
Group 29 100-110
Group 31 130

What's more AGM's are SEALED Valve Regulated Lead Acid. Adding distilled is NOT an option Thus the total life tends to be less than with Flooded types.

I'd stick with GC-2

[pianotuna]

least maintenance is a single group 29 AGM with a modest solar charging system including temperature compensated voltage.

[marcsbigfoot20b]

2oldman wrote:

HTElectrical wrote:
what would be the the most economical, trouble free, dependable way to go?

You don't get all those in one purchase. AGMs are about as trouble-free as it gets, but they aren't considered "economical" if that means the cheapest.

marcsbigfoot20b27 wrote:
According to many, having one bad GC2 in a pair is nearly impossible. :R

It is if you take care of them properly, and don't try to get 15 years out of them. A 12v battery can suffer damage just as easily. I guess the eye roll indicates sarcasm.

Yes, :B
I should have included a :W

[MEXICOWANDERER]

With a limited budget there is no perfect answer for this. Choose your compromise and learn to live with it. Forgetting or not wanting to water a battery is a human and not battery fault unfortunately. I would do everything I could to make the task as least offensive as possible.

There is nothing to be done about high temperatures accelerating plate dissolving with hot acid. Thicker plates last longer - cost more. And are only available in golf cars batteries and other more expensive accumulators. An irressolvable quandary.

[Sandia_Man]

Personally, I would stick with the GC2 pair of 6 volt batteries with the exception that we purchased ours from Samsclub. We primarily camp without hookups and our pair of GC2 Interstates were still delivering decent power after 8 years when we traded them in for a new set from Samsclub. Just wanted a fresh set and cost was what I spend on gas for a single RV outing. We got way more than we paid for.

It does sound like you could just use a single 12 volt battery since you run your genny around the clock when off the power grid. We prefer to just have extra amphours in case we need it, although we have an onboard Onan and a Champion inverter genny, plus solar which sounds like overkill, we definitely don't want to be caught with out power since we find ourselves RVing in extreme temps from time to time.

As you noted, the way a battery is charged and maintained is of paramount importance for proper performance and extended longevity. We have a smart charging converter and our rig is always plugged in when stored at home, batteries are always fully charged and ready to go. Nothing wrong with buying a higher-end battery, but they will suffer the same outcome without proper charging and maintenance.

[DiskDoctr]

This spring I asked similar questions and it was impressive the amount of knowledge and information shared by folks on here.

My main decision point was deciding between 2- 6v GC's or 2- 12v Group 31's.

For extended boondocking with occasional generator use to recharge, I wasn't sure if I'd need more. If I did, I could add ONE 12v (3 total), but would have to add TWO 6v (4 total).

In the end I elected to build a large battery box out of a truck tool box and use 4- 6v GC batteries, new converter, and pure sine wave inverter.

On our previous camper, we didn't boondock as much. We had the old converter and a pair of Group 31's (up from original single Group 27). They served us well.

We did upgrade all lights to LEDs, which REALLY helped.

As for the tech part of it, a lot of smart fellows on here 😉