Costco GC2 Batts

Interesting link.

The screwy31 is a 12v group31 USbattery, and I can say the 15.3v finishing/absorption voltage, was key to keeping the specific gravity walk every cycle down to a minimum when cycled deep, daily.

14.7v was a joke and Specific gravity would tank if all it got each day was a few hours of 14.7v.

The 12v battery in that link says a 15.5v absorption voltage! And only 15.6v equalization.

Now a word from out resident USBattery nemesis......
He might start sputtering something about Herb Tarlick and paisley ties :)

hammick wrote:
The Costco and Sams Club GC2s are Interstate branded and made by US battery. They require a 15.3 volt absorption charge which is no easy task. Your stock converter or stock solar charger controller will mean a short life. If your are going to go the GC2 route you have to study up on the getting them properly charged and buy a good solar charge controller and probably something to properly charge them when it's cloudy or in the winter.

Interstate GC2 charging specs

Setting your charging system up correctly makes more of a difference in battery life in my experience than does the brand you purchase. Unfortunately, that isn't always easy as they put garbage converter/chargers in from the factory. My current rig came with a PD 9280, which is pretty much garbage, no adjustability, and of course poorly installed by the trailer manufacture which makes it even worse. On the plus side, I do have my solar charge controller set up right for my Interstate batteries. You also have to keep in mind that things like the electronics of my Norcold Refrigerator have max voltage limit of 15.4 volts, so you have to make sure your set up to not go above that when it gets cold if you're using temperature compensation. While I only used solar maintainers on my two previous rigs, they were big enough to fully charge my batts once the battery switch was turned off, which went a long ways towards giving me good battery life since I couldn't plug my trailer in to fully charge in the storage lot.

Keep um wet, fully charge as often as possible and you can generally get good performance for a lot of years.

Good battery good charging = Happy Camper
Omitting one of the two makes for a busy forum.
Omitting both makes an ex-RVer.

What inverter are you using? What is the wattage when the air is running? Voltage drop on the batteries?

3 tons wrote:
Well, since I never drive the camper over the greens, and can run my 11k air conditioner for short periods (30 to 60 min, depending on SOC) off of two 208 a/hr Costco $85 GCs, I believe thay are a serious alternative to the 'better' brands....JMO from actual personal experience....

3 tons

Hahahaha on one of your trips to Costco try and sneak back to the loading dock and snort a dose of reality. I worked out the math for a vendor re how much a warranty really costs and he then went Trojan 100%.

Again cents per kWh is the only intelligent way to measure a cyclable battery. Avoiding this calculation is bunk science and economics

I could not agree more.

Once we get to more exotic technologies the same rule should apply. I'm intrigued by the new carbon foam jars. I must try to research them somehow.

MEXICOWANDERER wrote:
Again cents per kWh is the only intelligent way to measure a cyclable battery. Avoiding this calculation is bunk science and economics

let's have some fun shall we ? Say your battery bank is Interstate (Costco) CG2-RD at 208 AH 107 minute 75 AMP reserve rate. Let's look at the charging specs shall we? Charging amps at C/10 = 23.2. Bulk at 14.46 to 80 percent of SOC. Then absorb at 15.3 for 2 to 4 hours to 97% then float at 13.4. The resting voltage is 12.96 and specific gravity is 1.285 fully charged.(although every one I have dipped fully charged has been 1.300 specific gravity on new batteries.)

How many charger's that you know of can do this? (The one I use that does cost over $600) And you can count on one hand how many converter's can do this. (But you would need to chop off all your fingers and thumb to get the correct number ??)

Battery construction: Hybrid, It has a low antimony (under 2 percent) positive plates and calcium negative plates. So why is this construction important? A high antimony 5-6% battery will accept a charge real well if deeply discharged. If over charged or high float voltage, will cause the negative plate to be poisoned by antinomy. This cause's excessive water use and big self discharge. The advantages of a calcium battery are tolerance to heat, low water consumption and a low discharge rate.

So a Hybrid battery advantage would be lower self discharge (especially when new) slower negative plate antinomy poisoning from overcharging. Better in higher heat and lowered water consumption.
The disadvantage is it is more difficult to recharge during deep discharge. Less antinomy. Calcium creates a oxidation boundary layer on the negative plate during a deep discharge that resists the charging process. ( This is the reason for the higher absorb voltage) Also a higher specific gravity acid will give more AH for a given construction....... But at a cost of a higher plate corrosion rate.
So why would they build a Hybrid deep cycle? That's easy, "longer shelf life" (lower self discharge) and lower "warranty" issue's due to better tolerance to overcharging and antinomy poisoning.

There are other ways to charge that battery. A lot has to do with how it is discharged. (How many amps and DOD as well as frequency of discharge)

Oooooo the boys are feeling the heat...

"Let's make it reeeeaaaal complicated so it impresses the guy who signs our checks"

That charging formula listed above is wholly, purely, totally, and absurdly asinine. How's that for directness?

Try as I might to simply the process to realistically attain full cell gravity along comes someone who reads idiot originated material then pontificates it as being "recommended".

I told you folks a few years ago these jerks were going to up cell electrolyte density to pull a pea and three walnut shells prestidigitation act on the public. If that 1.300 reading is from a known accurate hydrometer then the absurd has become reality.

Hybrid construction is a compromise. ALL TYPES OF BATTERY CONSTRUCTION ARE COMPROMISES. Clear? Antimony poisoning of lead dioxide negative plates can be controlled with float voltage control. This is not Toroid Fusion Containment level Science. Still clear?

The OPTIMUM metallurgy for a flooded deep cycle battery is 5% antimony positive and lead dioxide negative PURE VIRGIN LEAD PLATES. Electrolyte density temperature adjusted.

The 5% antimony construction demands unique maintenance, just as various other metallurgy demands their particular maintenance.

But the 5% antimony lead dioxide metallurgy yields by far the longest lived, and most durable flooded deep cycle battery. No we are not talking about car batteries. A deep cycle flooded battery must be represented by a CHART depicting depth of discharge versus number of expected cycles.

Run run run...

Try and get such a chart from a hybrid manufacturer. Oooooo they don't have them do they. Does Johnson Out Of Control or US Battery or any others have a life cycle chart for their low antimony batteries. Ooooooo why not?

If total kWh life cycle cost is ignored you become a victim not a smart consumer.

I am going to have to cut and paste to disk that absurd charging formula above. The original US Battery "Contains Miracle Selenium Additive" laugh-a-mania wore thin years ago.

Why not ask the Bozos (capitalized) exactly how they green their batteries. That ought to shut them up. Or ask them the purity content of the recycled Pb they use, citing SPECIFIC percentage of impurities.

There are few things I dislike more than Herb Tarlek driven idiots fearful of pink slips on Friay issuing bafflemwithbullshit hyperbole. You done struck a nerve.

jake2250 wrote:

Nunyadamn wrote:
I am pretty sure you could take it back to Costco for a replacement/refund. That's the best benefit of being a Costco member, they will take almost anything back.

Probably so, but the age factor and mixing old and new,, Five years is standard life of a battery so for the $42 difference in the two sets,, I will hope I get the better battery and be happier.

They never tested mine. I have a pair of starter batteries in my diesel truck. They sounded weak when cold weather came along. I took them both back and they never questioned me. Full replacement after 2-1/2 years. They even refunded the price increase that had occurred during the 2-1/2 years.

The real reason they failed was because I didn't drive the truck enough.

The average life of a properly cared for quality GC220 golf car service battery is 700 cycles.

Even under maintenance only conditions 52 months is quite enough to allow a 5% antimony battery to vigorously disagree with its new neighbor. There is one trick however than mustn't be allowed to believe it will automatically agree with the batteries and make them friends.

Connect the batteries in series. Six cells. No need to do this test disconnected but it is very necessary to isolate the linked batteries to chassis negative or positive. Six cells in series.

Charge both batteries to their max fill point.

Let them sit for a week after charging them. Then measure 3 cell voltage totals for both batteries - two voltage readings.

.15 fifteen one hundredths of a volt difference is the go-no-go line voltage limit. Then during the remaining lifespan of the old timer repeat this test every Spring.

People hate hydrometers. I dislike going to the dentist but I will be darned if I will suffer a toothache.

As long as those 2 batteries remain reasonably close in voltage and electrolyte density tests keep using old with new. The alternative of course is to purchase a second battery.