# Batteries For Solar Power System



## YuccaFlatsRanch (May 3, 2004)

Costco has Golf Cart batteries (GC2) that are 6 volt 215 amp hour batteries that can be recharged 700 times for $79.00 plus a $9.00 core charge. Two of these wired in series gives a HEAVY DUTY 12 volt system that cost's about $200.00. I think these batteries are a much better way to go than normal deep cycle batteries that are 12 volt and can only be recharged 200 times.


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## ET1 SS (Oct 22, 2005)

hmm, could be.


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## Jim-mi (May 15, 2002)

Please define what you are calling "normal deep cycle" . . . ????

Didn't know anybody called a 12v a 'deep cycle' . . .??

All I know about are 2 and 6 volt.........

And somebody is blowing smoke about those recharge time limits.......


For years the Trojan T105 has been a base line 6v battery for small systems.........


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## Sonshine (Jul 27, 2007)

We have 12 volt deep cell marine batteries. Not sure about the recharge limits on them.


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## ET1 SS (Oct 22, 2005)

I have some 12VDC deep cycle batteries.


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## terri9630 (Mar 12, 2012)

We have the deep cycle marine batteries in our camper and horse trailer. The 2 in the camper are almost 4yrs and the one on the horse trailer is 2yrs. They have solar chargers so that is a lot of charges. I've never heard of a "charge number" before.


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## Jim-mi (May 15, 2002)

Those 12v **Marine** batterys are not a real deep cycle bat.
They are a hybrid. . . . . .A car battery with thicker plates .. . 
.But not near as thick as a true *deep cycle* bat..........

That Costco price might be OK for what it is..............

comparing apples to oranges doesn't work...............


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## JohnP (Sep 1, 2010)

YuccaFlatsRanch said:


> Costco has Golf Cart batteries (GC2) that are 6 volt 215 amp hour batteries that can be recharged 700 times for $79.00 plus a $9.00 core charge. Two of these wired in series gives a HEAVY DUTY 12 volt system that cost's about $200.00. I think these batteries are a much better way to go than normal deep cycle batteries that are 12 volt and can only be recharged 200 times.


That's a good price. Any brand name? I didn't see any at coscto.com. 220AH is standard but 215's not too far off. I got Interstate's new GC2-XHD and they're 232AH but I paid 125 for them.


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## YuccaFlatsRanch (May 3, 2004)

Any battery can only be discharged to I think it is 50% of charge and then recharged so many times and it has to do with the thickness of the plates. Typical marine deep cycle/trolling motor batteries are warranted to have approx 200 said charges before the plates are shot. Gold Cart batteries which are 6 volt and in a case both wider and deeper than a Marine battery have much heavier and much larger plates and are rated to have about 700 said charges. One of the tricks is to not let the batteries get too discharged. On the internet the Costco batteries are said to be made by Trojan and in fact the cases other than color look identical.


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## YuccaFlatsRanch (May 3, 2004)

I looked up the Interstate GC2-XHD and it looks the same as the Costco batteries including having the same case colors. HMMMMM


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## YuccaFlatsRanch (May 3, 2004)

Here is a neat description of Cycles vs Battery Life:

"Cycles vs Life

A battery "cycle" is one complete discharge and recharge cycle. It is usually considered to be discharging from 100% to 20%, and then back to 100%. However, there are often ratings for other depth of discharge cycles, the most common ones are 10%, 20%, and 50%. You have to be careful when looking at ratings that list how many cycles a battery is rated for unless it also states how far down it is being discharged. For example, one of the widely advertised telephone type (float service) batteries have been advertised as having a 20-year life. If you look at the fine print, it has that rating only at 5% DOD - it is much less when used in an application where they are cycled deeper on a regular basis. Those same batteries are rated at less than 5 years if cycled to 50%. For example, most golf cart batteries are rated for about 550 cycles to 50% discharge - which equates to about 2 years.

How depth of discharge affects cycle life on batteriesBattery life is directly related to how deep the battery is cycled each time. If a battery is discharged to 50% every day, it will last about twice as long as if it is cycled to 80% DOD. If cycled only 10% DOD, it will last about 5 times as long as one cycled to 50%. Obviously, there are some practical limitations on this - you don't usually want to have a 5 ton pile of batteries sitting there just to reduce the DOD. The most practical number to use is 50% DOD on a regular basis. This does NOT mean you cannot go to 80% once in a while. It's just that when designing a system when you have some idea of the loads, you should figure on an average DOD of around 50% for the best storage vs cost factor. Also, there is an upper limit - a battery that is continually cycled 5% or less will usually not last as long as one cycled down 10%. This happens because at very shallow cycles, the Lead Dioxide tends to build up in clumps on the the positive plates rather in an even film. The graph above shows how lifespan is affected by depth of discharge. The chart is for a Concorde Lifeline battery, but all lead-acid batteries will be similar in the shape of the curve, although the number of cycles will vary."

it is from Here: Deep Cycle Battery FAQ


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## terri9630 (Mar 12, 2012)

Interesting. We have our camper, horse trailer and camper generator batteries set up on a solar trickle charger.


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## JohnP (Sep 1, 2010)

I thought Interstate was the only one who had black with the bright green top. Kind of their trademark.
I did a little searching on costco batteries and found they are Kirkland brand but that's just costco's house brand for many things. Also found a couple of sites that said they are made by Johnson Controls. One site said they also make diehard, duralast and Interstate. I'd heard years ago that there were only one or two companies that make all car batteries. Naturally all batteries look alike on the outside with the exception of plastic color. I bought interstate because they were close to where I lived in FL and when I looked online for retailers where I was moving to in MO I found quite a few interstate but the only trojan retailers were in KC or St Louis and I didn't want to go there for warranty issues or to get more matching batts. That and the 232AH rating compared to T-105's 220AH rating. No complaints yet. It's only been just over a year but they're going strong as ever.
But for the price I wish I'd have gone to costco or sam's. I paid $25 for a core charge. That was an extra $100 for 4 batts. That was comparable to all the other golf cart shops I tried and I didn't know sam's/costco even sold them at the time. So I've got $500 into these 4 batts and could have got walco/costmart for less than 400. Being my first set of batts that everyone says I will trash quickly I would have gone for the low price. Oh well.
One thing to note is that if Johnson Controls does indeed make all these batteries, it doesn't mean they're all the same quality. Look at walmart. They have all kinds of things made extra cheap for them. Buy a presto 16qt canner at walmart and buy one anywhere else. There's a difference. At least with the canner I can see the difference.


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## YuccaFlatsRanch (May 3, 2004)

One really good thing about almost anything from Costco is their return policy. They will just about take anything back. I told the lady that one of my puppies chewed through one of their lifetime guarantee water hoses - she said bring it back - they are 100% lifetime guaranteed. I cannot stoop that low. I will repair it with hose repair junctions.


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## ET1 SS (Oct 22, 2005)

As it turns out, I had an appointment today with a guy who designs and installs off-grid systems. His preference is to install enough batteries so that you never 'cycle' below 80%. If you ever go down to 60% then you clearly do not have enough batteries in your battery bank.

He recommends using Rolls Surrette L-16 Deep Cycle Batteries [2 Volt].


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## Jim-mi (May 15, 2002)

The Surrette batteries are premium.


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## logbuilder (Jan 31, 2006)

ET1 SS said:


> He recommends using Rolls Surrette L-16 Deep Cycle Batteries [2 Volt].


Actually 6 volt and about $375 each.

Here is a link for more info.

http://www.solarelectricsupply.com/Batteries/Rolls-Surrette/L-16.html


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## ET1 SS (Oct 22, 2005)

logbuilder said:


> Actually 6 volt and about $375 each.
> 
> Here is a link for more info.
> 
> Rolls L-16 6 Volt Deep Cycle Battery - Solar Electric Supply


I think they are available in 2VDC, 4VDC and 6VDC.


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## logbuilder (Jan 31, 2006)

ET1 SS said:


> I think they are available in 2VDC, 4VDC and 6VDC.


You might very well be right. I am only familiar with the 6V. They are too rich for my pocketbook, that's for sure.


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## ET1 SS (Oct 22, 2005)

I think I figured it out some. 

There is a company that has two primary [and symbiotic] focuses: modular homes and off-grid solar. The guy I had an appointment with is the closest guy to my location, who designs and installs systems. He is also the regional outlet for this company.

His location is just off the interstate, on the primary route taking tourists up to a hot-spot tourist region.

I bet that his primary clientele are out-of-state folks who buy lots up in the popular tourist area, and who want to plop down $1Million for their dream vacation cabin in that area.

Which is why he can be a distributor for 'top-line' components that cost way more than needed.


I can see the rationale in building a battery bank using massive 2VDC batteries, they are very high wattage. So when doing the design calculations it makes sense. [without any regard for cost].


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## YuccaFlatsRanch (May 3, 2004)

"[without any regard for cost]."

That immediately signals to me that they are way beyond what I can even dream of affording. 

It's like buying a new Mercedes. I can buy either 2 or 3 Volkswagon diesels for the price of 1 Mercedes. If I were to keep 2 up on blocks while I drove the 3rd for 250,000 miles I would have 2 "new ones" to use when I got tired of the first one. The Mercedes guy would have traded in his Mercedes on another or two and be even further in debt.

IF I could find the GC2 Batteries DRY from Interstate, think of how many extra ones I could buy from them for the price of one from Rolls ...... battery.


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## ET1 SS (Oct 22, 2005)

There is a 'Batteries Plus' store in the City. I have gone to them a few times in the past. They rebuild cordless tool batteries. Since they focus on batteries they usually seem to be fairly knowledgeable on the topic.

If you have any store like that in your area. I would say to go and talk to them.

I plan to talk to the guys here, and say what their opinion is.


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## Jim-mi (May 15, 2002)

The customers that I have installed either 2 volt or 6 volt Shurretts in their systems are very happy with them.

Shurretts's are not too good for **beginners** who will end up going thru a set of bats while they are "learning" 

ET1 SS; from your postings, I believe you have the right attitude to be able to handle the good stuff.
All in all they are . . .in the long run . . .not that much more than say Trojan........

As you go down the price list . . so also goes the quality..........

your choice............


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## unregistered41671 (Dec 29, 2009)

Jim-mi said:


> The customers that I have installed either 2 volt or 6 volt Shurretts in their systems are very happy with them.
> 
> Shurretts's are not too good for **beginners** who will end up going thru a set of bats while they are "learning"


I am a beginner.....could you elaborate more please. Thanks


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## ET1 SS (Oct 22, 2005)

If you start with a battery bank that is too small. They will cycle too deeply each day, and within 2 years you should be seeing dead cells.

The fix is to first replace the batteries you have killed, and then to double the size of your battery bank.


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## unregistered41671 (Dec 29, 2009)

ET1 SS said:


> If you start with a battery bank that is too small. They will cycle too deeply each day, and within 2 years you should be seeing dead cells.
> 
> The fix is to first replace the batteries you have killed, and then to double the size of your battery bank.


Makes sense. Thank you.


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## Jim-mi (May 15, 2002)

Reguardless of the size of the battery bank "off gridders" Must learn to monitor the batt bank.
A Tri-Metric is one good way to do so . . .. . .program it properly and then read it for the batt state of charge . . . . . . .
. ."Beginners" tend to use it (their batt bank) "till the light goes out" . . .of course that means the batt is very deeply discharged.. . . . .NOT good.

. . "Beginners" with a self installed system invariably miscalculate their needs for such and such that needs to run 24/7. . . . .. .

Batteries DO have a memory . . .so when "Beginners" run a batt down 80 - 90 % time and time again,. .those occurrences just add another nail in the coffin ..........

And in short order . . . ."Dam . .The battery is shot" . ."How come" . . .???

Because YOU abused it ............................


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