Are GC2s really better than Grp 27s?

[ramblinrod]

Originally Posted by pcmm

I still think that you are missing the fundamental difference between these batteries. grp27 batteries are easy to find, the ones you can get "everywhere" will be starting batteries with many thin plates designed to provide a lot of amperage for a brief period of time which is the opposite of what we are looking for in these applications. Over time, under low loads they more easily develop permenant sulfation. This leads to them being replaced more frequently. When comparing batteries, weight is just a factor. deep cycle batteries tend to be heavier than their "starting" versions, but the difference isn't dramatic. maybe a couple of pounds. For practical purposes the "pairing" problem isn't a problem. in a pinch you can replace a 6v bat with minimal negative effects. Its not ideal but replacing 1 battery is better then switching out 2. The reason GC2's are generally so cheap ( compared to the "boutique" Trojan brands) is the shear volume that they are produced in.

I agree that SC225's are great batteries, but trying to find them well that's much more difficult and they are much more expensive than GC2's

FYI as an example if you look at West Marine GC2's you'll be paying $240 per battery for the exact same battery as a Sam's club GC2 (ask me how I know and I'll PM you)

Marine / RV grp 27 deep cycles are available from almost any battery supplier. I know some claim they are not "true deep cycle" because the plates aren't as thick as GC2s and the plate free reservoir at the bottom isn't as deep. BUT the amount of lead is virtually identical, just configured differently, and the reservoir above the plates is deeper (as required to prevent plate exposure and battery damage due to regular deep cycles).

So the issue is, I've heard people say GC2s are better, but my experience is that they really aren't, unless on compares a Trojan 6Vdc GC2 $$$$ to an East Penn grp 27 DC $. But by the same token, comparing a Trojan 12 Vdc SCS 225 $$$$$ to a no-name GC2 $, the GC2 sux.

The whole point is, a whole lot people believe GC2s are inherently better than Grp 27s. Are they, when comparing quality to quality or cheap to cheap?

[newhaul]

Rod acording to dyno.specs.the gc2 positive plates are.105 thick and the positive.plates in the grp27 is only .070 and they are not almost.identical as you suggested

[pcmm]

Originally Posted by ramblinrod

Marine / RV grp 27 deep cycles are available from almost any battery supplier. I know some claim they are not "true deep cycle" because the plates aren't as thick as GC2s and the plate free reservoir at the bottom isn't as deep. BUT the amount of lead is virtually identical, just configured differently, and the reservoir above the plates is deeper (as required to prevent plate exposure and battery damage due to regular deep cycles).

So the issue is, I've heard people say GC2s are better, but my experience is that they really aren't, unless on compares a Trojan 6Vdc GC2 $$$$ to an East Penn grp 27 DC $. But by the same token, comparing a Trojan 12 Vdc SCS 225 $$$$$ to a no-name GC2 $, the GC2 sux.

The whole point is, a whole lot people believe GC2s are inherently better than Grp 27s. Are they, when comparing quality to quality or cheap to cheap?

You're still missing the point. The total lead weight may be the same but the configuration of the lead is VERY important, a lot of thin plates allow higher discharge capacity but aren't good for long slow low amperage discharge. Facts are facts. The whole thing gets muddied by the fact that most boaters abuse their batteries. Even between "quality" and cheap GC2's the confuguration is going to be basically the same. thicker plates in the GC batteries allow them to sustain longer low amperage discharges.

If that were the case, floor scrubbers and other long use items would just have a bunch of gr 27's in them but fact is they don't L16's are 1 step away from the traction batteries found in fork lift trucks and those batteries are seriously cycled daily. Starting batteries would never last in those situations.

Oh and "dual purpose" grp 27's which is what you are talking about are no different than starting grp 27's PM me and I can let you know why!!

[mitiempo]

Rod

"So if there is so much extra lead where is it?"

It is actually quite simple, but you are ignoring it to try to prove your point. Yes, there is almost the same amount of lead in a group 27 as there is in a T-105. But the lead in the group 27 is split into 6 groups while the T-105 only splits it into 3. The result is thicker plates and assuming the same treatment more cycles.

As far as the SC-225 goes it is a premium 12 volt deep cycle battery - worlds apart from the average group 27 start, quasi deep cycle or combination type battery that commonly sells for about $100 or so.

And based on equal comparison a SC-225 will not cycle anywhere near as many times as a T-105.

[newhaul]

Ok folks it just dawned on me rod is comparing a single grp.27 12v battery to have the same ammount of lead as a gc2 battery at 6v ( which actually has almost.20percent more lead) whereas when you hook two in series to produce the 12v you have well over double the lead in adition to the fact.the plates are 1/3 thicker. ( using the specs from dyno)

[ramblinrod]

Originally Posted by newhaul

Rod acording to dyno.specs.the gc2 positive plates are.105 thick and the positive.plates in the grp27 is only .070 and they are not almost.identical as you suggested

I did not suggest GC2 plates and Grp 27 plates are the same thickness.

Not once.

Please reread my post(s) you are referencing.

What I stated (and it is true), that for some manufacturers (not Trojan), the GC2 vs Grp 27 battery volume and weight are virtually identical, therefore, they likely have the same total amount of lead, just in a different configuration. (Meaning the GC2s have thicker but fewer plates.)

My question is, do GC2s have to have thicker plates just because they have the same w-hr capacity with fewer plates?

Makes sense to me. The lead has to go somewhere. If GC2s had the same thickness of plates as Grp27s, they would weigh a lot less, and have a lot lower A-hr rating.

I don't believe the thicker plates really make them any more robust or longer living. I believe the plates have to be thicker, just because they are fewer, otherwise the w-hr rating would be a lot lower.

In the past, some have attributed the thicker plates to being longer lasting, but I don't believe it, since in my experience GC2s and Grp 27 deep cycles, of similar quality, treated approximately the same wrt depth of discharge and charge regime, seem to last about equal (~ 2 years treated badly, to ~ 6 years treated well).

[ramblinrod]

Responses in bold red.

Originally Posted by mitiempo

Rod

"So if there is so much extra lead where is it?"

It is actually quite simple, but you are ignoring it to try to prove your point.

I am not ignoring anything.

Yes, there is almost the same amount of lead in a group 27 as there is in a T-105. But the lead in the group 27 is split into 6 groups while the T-105 only splits it into 3.

Correct

The result is thicker plates

Correct

and assuming the same treatment more cycles.

Not in my experience. A grp 27 and GC2 of equal quality and equal weight last about the same number of cycles.

As far as the SC-225 goes it is a premium 12 volt deep cycle battery - worlds apart from the average group 27...

Correct, just as a T105 is worlds apart from a no-name GC2.

And based on equal comparison a SC-225 will not cycle anywhere near as many times as a T-105.

This is contrary to my belief. How did you draw this conclusion?

[ramblinrod]

Responses in bold red.

Originally Posted by newhaul

Ok folks it just dawned on me rod is comparing a single grp.27 12v battery to have the same ammount of lead as a gc2 battery at 6v

Correct, this is exactly what I have been saying as clearly as I possibly can.

( which actually has almost.20percent more lead)

This is only true when comparing a Trojan GC2 and Grp 27. When comparing other manufacturers, their GC2 and grp 27s are virtually the same weight.

whereas when you hook two in series to produce the 12v you have well over double the lead

Yes, and when you connect 2 x Grp 27s, you have double the lead of a single GC2, so what?

in adition to the fact.the plates are 1/3 thicker. ( using the specs from dyno)

Correct, GC2 plates are thicker; they have to be, or everything else equal, with only 3 cells, they would weigh a lot less, and the A-hr rating would go way down.

[newhaul]

Ok I see the diference now you added the part about some manufacturers .I have found this info on trojans the t125 6v weighs 66 pounds and the 27tmx weighs 55 pounds so thats a considerable diference.in weight there to . So they are not virtually identical in weight. As you sugested.
One more.thing rod I posted links to the dyno website showing all of their battery specs. Where are your links and empirical data

[mitiempo]

Here are the lab comparisons for Trojan batteries. The T-105 gives more cycles than any of the 12 volt batteries as well as more cycles than almost all their 6 volt batteries. Valid comparison from one of the most respected battery manufacturers in North America.





754 cycles for the T-105 vs 300 for the SC-225.

Thicker plates (more lead in other words) does equal more cycles.

[ranger58sb]

Originally Posted by ramblinrod

Marine / RV grp 27 deep cycles are available from almost any battery supplier. I know some claim they are not "true deep cycle" because the plates aren't as thick as GC2s and the plate free reservoir at the bottom isn't as deep. BUT the amount of lead is virtually identical, just configured differently, and the reservoir above the plates is deeper (as required to prevent plate exposure and battery damage due to regular deep cycles).

So the issue is, I've heard people say GC2s are better, but my experience is that they really aren't, unless on compares a Trojan 6Vdc GC2 $$$$ to an East Penn grp 27 DC $. But by the same token, comparing a Trojan 12 Vdc SCS 225 $$$$$ to a no-name GC2 $, the GC2 sux.

The whole point is, a whole lot people believe GC2s are inherently better than Grp 27s. Are they, when comparing quality to quality or cheap to cheap?

Given similar weights, isn't the different configuration the more significant factor, though? If the amount of lead is a constant, but there are fewer plates, the plates must be thicker... and thicker plates is a better thing? The deeper reservoir is a better thing?

I don't know that "most people" think any GC2 is inherently better than G27s in general. Maybe.

It wouldn't surprise me if many people compare either within a brand (Trojan GC2 to Trojan G27, for example... or Costco GC2 to Costco G27), or within a type by price (Trojan GC2 vs. Costco GC2, etc.).

-Chris

[newhaul]

Originally Posted by mitiempo

Here are the lab comparisons for Trojan batteries. The T-105 gives more cycles than any of the 12 volt batteries as well as more cycles than almost all their 6 volt batteries. Valid comparison from one of the most respected battery manufacturers in North America.





754 cycles for the T-105 vs 300 for the SC-225.

Thicker plates (more lead in other words) does equal more cycles.

Now that's the evidence and numbers that I am talking about that rod seems to not be able to present. ( thank you) kinda shoots a few dozen holes in Rods theory)

[newhaul]

Just found a reason to go with the cheapest batteries you can get away with if they are made by east Penn they now only have a 6 month warranty on all of the batteries that are manufactured by them. Makes me glad I have a dyno with a 60 month . BTW if you purchase from fisheries supply they ship to you for free ( all orders over $99 so sayeth their web page) . I pick up in store here.

[pcmm]

Originally Posted by newhaul

Just found a reason to go with the cheapest batteries you can get away with if they are made by east Penn they now only have a 6 month warranty on all of the batteries that are manufactured by them. Makes me glad I have a dyno with a 60 month . BTW if you purchase from fisheries supply they ship to you for free ( all orders over $99 so sayeth their web page) . I pick up in store here.

Actually if you look on their website its a 12 month free replacement warranty. you can get around that anyway, by purhasing a Deka battery that is rebranded. probably 80% of their batteries are OEM'd EG Toyota, honda, Mazda, BMW, Duracell etc. are all Deka batteries.

[ramblinrod]

Originally Posted by newhaul

Now that's the evidence and numbers that I am talking about that rod seems to not be able to present. ( thank you) kinda shoots a few dozen holes in Rods theory)

Not really.

If one reads the Compass Marine article that everyone frequently refers to, they will read that the lab cycles mean nothing in the real world. This is consistent with my experience.

In that article, there is an ASSUMPTION, that the lab cycles (within a single manufacturers product range) may be directly proportional to real world cycles.

That may be a valid assumption, that could be verified, OR NOT.

In my experience, the real world cycles between GC2s and grp 27s is not so dramatic, if at all.

While I agree that Trojan is perceived as a high quality manufacturer, their GC2 weighs significantly more than their Grp 27, AND IT COSTS MORE.

Assuming this superiority occurs in other brands as well is a VERY BIG ASSUMPTION, especially when the GC2 and Grp 27 weigh the same.

I personally do not believe the real world life expectancy of a Trojan GC2 is that much greater than a Trojan grp 27. (I am following a cruiser that just had to replace his bank of 4 x T105s that were less than 2 years old. Their batteries have sat in float mode the vast majority of their lives.)

For Rolls (formerly Surrette) which I believe to be an even higher quality brand than Trojan, their A-hr ratings, weight, and cycles between GC2 and GRP 27 compare much closer. The GC2 cycles being slightly higher, about proportional to the additional weight of the GC2 over the Grp 27.

So I wouldn't be too surprised if real world T105 cycles were somewhat better than their grp 27. Based on my experience to date, I would be extremely surprised if it was significantly more, everything else being equal.

I would expect the real world T105 cycles to be greater than their Grp 27 cycles, by the same proportion that they differ in weight.

Again, my total premise is that everything else being equal, the performance of a GC2 should be the same as grp 27 DC.

If a referenced manufacturer (Trojan) builds a superior GC2 to their Grp 27, it may last longer (in the real world) but we have no real empirical evidence of this.

If a manufacturer builds an inferior GC2 to the referenced manufacturer, we have no idea how that product will compare in real world applications.

Therefore, my expectation is, the cheap GC2s everyone believes are a great bargain, prolly aren't.

Hence the original premise, that people switching from grp 27s to GC2s may not be realizing the benefits they think they are.