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ranger58sb · 16-12-2016, 04:23

Quote:

Originally Posted by ramblinrod

Reasons for sticking with Grp 27s instead of GC2s

1. Availability. 12 Vdc Grp 27s are available everywhere. GC2s, not so much.

2. Usable voltage. Small (or independent) systems: If a single 100 A-hr Grp 27 is plenty for the intended app (say bow thruster), for GC2s it would take two batteries to make the necessary 12 Vdc.

3. Loss of capacity on failure. If a house bank consists of 2 x GC2's and one develops a shorted cell, 100% of capacity is lost, whereas 2 x Grp 27s, you can run on one and only loose 50%. For 4 x GC2s if one goes down 50% of capacity is lost as two have to be taken off the bank, whereas for 4 x Grp 27s, only 1 battery (25%) capacity is lost.

I think all very valid points... but I also think this is application specific. IOW, for a starter battery in a boat that normally uses -- and can only make space for -- 2x G27s... sounds good. Ditto for house batteries in a boat that only has room for 2x G27s.

But a lot of that goes south in boats with more battery space. I can fit 4x GC2s (~440 Ah) in the same area where I now have 3x G31s (~300 Ah), counting a very little unused space that's there now. So which battery is better?

Still no answer, at least from me. I can say 440 Ah is more than 300 Ah. For me, 440 Ah will be better than 300 Ah, once I eventually make that swap. That still doesn't say to me GC2s are a priori better... just that they would provide better capability for this one application I have in mind.

Quote:

Originally Posted by ramblinrod

Just did a search on Costco and Walmart sites, lots of 12 Vdc batteries, not one 6 Vdc. No Sam's Club in Canada. We do have Canadian Tire, a huge automotive / all house wares chain; lots of 12 Vdc / no 6 Vdc batteries listed.

Did you check golf courses? Or their battery suppliers?

-Chris

ramblinrod · 16-12-2016, 10:49

Quote:

Originally Posted by ranger42c

I think all very valid points... but I also think this is application specific. IOW, for a starter battery in a boat that normally uses -- and can only make space for -- 2x G27s... sounds good. Ditto for house batteries in a boat that only has room for 2x G27s.

But a lot of that goes south in boats with more battery space. I can fit 4x GC2s (~440 Ah) in the same area where I now have 3x G31s (~300 Ah), counting a very little unused space that's there now. So which battery is better?

Thanks for the thoughtful comments Chris.

I suspect the local golf courses get their 6Vdc batteries from Toronto suppliers (min 85 miles away) but I will check into that.

I have done some on-line searching and was surprised to see some high volume golf cart battery suppliers are offering 6 x GC2 batteries for a price lower than 4 x Grp 27.

This certainly isn't true of the brands I consider "high or reasonable" quality.

I know that some products have higher margins than others due to competitive pressure, (previous commercial electrical device product manager) but that just doesn't make sense.

It makes me really question the quality of those GC2s. I saw one supplier where they refer to them as an unbranded battery made by Trojan, but they are lighter and lower A-hr rating than T105s.

As always, "buyer beware" and "the devil is in the details.

PS, grp 31s are a heavier and larger footprint.

You may wish to investigate if 4 x Grp 27s would fit. This would have a 400 - 440 A-hr rating, depending on brand and model, and you would not be exposed to the "disable 2 if 1 fails" dilemma.

ranger58sb · 16-12-2016, 12:38

Quote:

Originally Posted by ramblinrod

You may wish to investigate if 4 x Grp 27s would fit. This would have a 400 - 440 A-hr rating, depending on brand and model, and you would not be exposed to the "disable 2 if 1 fails" dilemma.

A single G27 is rated for up to 110 Ah? I'd have thought lower Ah rating than the larger G31... but hadn't really checked before... but I will.

That would lead back to whether 4x 6V "deep cycle" GC2s would be "better" or not for a house application compared to 4x 12V -- dual-purpose? -- G27s? (Have read there mostly aren't many (any?) "deep cycle" 12Vs out there...)

-Chris

pcusteau · 16-12-2016, 13:46

Quote:

Originally Posted by ramblinrod

Just did a search on Costco and Walmart sites, lots of 12 Vdc batteries, not one 6 Vdc. No Sam's Club in Canada. We do have Canadian Tire, a huge automotive / all house wares chain; lots of 12 Vdc / no 6 Vdc batteries listed.

Costco Canada does carry GC2 - I bought 4 to replace a pair of GRP 27 and have been very happy with them. I am told they are manufactured by Johnson Controls who has something like 70% of Led Acid global market share.

Granted I now have more Ah in my house bank then before, I chose these based on the following factors:

- Dirt cheap: these were about half the price of Trojan T-105 and I figured that even if they only last half as long I'd be ok.

- because of their format (more depth) I could fit 4 GC2 in just about the same space of the 2 GRP27 and end up with more Ah.

- Because of the lower plate density, they do generate less heat when fast charging at the dock or underway and I could see evidence of the previous GRP27 batteries having overheated in the past.

But I'll grant you that if not for the fact that I needed more Ah and the GRP27s were near their End of Life, I wouldn't have bought into all the hype.

As for manufacturers not fitting boats with GC2s in the first place: I think that for powered boats it's just more practical for them to have starter batteries and house batteries all of the same format. it just makes for a cleaner layout. That being said, my boat came with a house bank that was seriously underpowered in the first place - it came with only 1 GRP27 for the house bank and the second one had been put in by the previous owner and even at that it was still not enough - and yes I did also replace all the lights with LEDs and I think being underpowered forced me to become pretty good at managing power.

Crew of Turning · 16-12-2016, 14:11

I am almost reluctant to step into this thread but here goes and it is a one sided offering. The 4 GC2 batteries in our house bank were sold to the PO 6 years ago last July. I know this because I ordered them Into the Barrie West Marine store for him from East Penn. We acquired the boat 3 years ago after it sat at the dock much longer than it should have, However they started to get punchy this summer with heavy gassing and I noticed some case bulging around some of the posts. And, the hydration needs were so heavy and weekly. We replaced them with 4 units from Total Battery in Barrie....WM has closed out. The US Battery (4) that we bought were on sale for $130 CAD apiece, weight within a pound of the WM product. Are they any good ? time will tell. Our charging arrangement is alternator.solar.wind and shore based if required. You can always find stuff if you are lucky or motivated.
This past January we were in a resort in Cuba, all the staff were in golf carts and they had a fair sized charging station and all the batteries were Trojan T105.

**Symphony** · 16-12-2016, 19:35

There's more to a boat battery than purchase cost/Ah. My house and engine banks are under the berth, I don't want anything gassing or boiling there.

Weight is also important as well as charge acceptance, and a golf cart is not built for speed or to be lightweight.

The golf courses never expect their carts to roll over, and they trickle charge every night to 100%SOC. They have someone to dribble water in everyday too.

ramblinrod · 16-12-2016, 20:35

Quote:

Originally Posted by ranger42c

A single G27 is rated for up to 110 Ah? I'd have thought lower Ah rating than the larger G31... but hadn't really checked before... but I will.

That would lead back to whether 4x 6V "deep cycle" GC2s would be "better" or not for a house application compared to 4x 12V -- dual-purpose? -- G27s? (Have read there mostly aren't many (any?) "deep cycle" 12Vs out there...)

-Chris

Ratings vary by manufacturer, but for reasonable quality 12Vdc standard lead acid deep cycle batteries, they are somewhere in the neighbourhood of:

Grp 24 - 85 A-hrs
Grp 27 - 100 A-hrs
Grp 31 - 120 A-hrs

In many cases, the Grp 27 has a similar footprint to GC2s, slightly longer but much shorter in height. When you put 2 in parallel, they have very similar capacity to 2 GC2s in series, perhaps 10% less. Then again, if the Grp31s will fit, their capacity is about 10% more.

mitiempo · 16-12-2016, 21:13

Quote:

Originally Posted by ramblinrod

Ratings vary by manufacturer, but for reasonable quality 12Vdc standard lead acid deep cycle batteries, they are somewhere in the neighbourhood of:

Grp 24 - 85 A-hrs
Grp 27 - 100 A-hrs
Grp 31 - 120 A-hrs

In many cases, the Grp 27 has a similar footprint to GC2s, slightly longer but much shorter in height. When you put 2 in parallel, they have very similar capacity to 2 GC2s in series, perhaps 10% less. Then again, if the Grp31s will fit, their capacity is about 10% more.

GC2s have virtually the same footprint as group 24 batteries. So as long as there is height available GC2s fit the same space. A pair of GC2s with 220 to 242 AH is a better choice for many than a pair of group 24s with 170 AH.

In this area - Victoria BC - GC2s are every bit as available as the 12 volt batteries. Costco, any dedicated battery retailer, as well as the store I work at - Trotac Marine. We sell a lot of 12 volt, mostly group 24 and 27, for small outboard and sterndrive boats as well as start batteries for larger power and sailboats. For house banks GC2s outsell all others by a wide margin.

We also take cores back, often only a couple years old if group 24 or 27. GC2's cores are in most cases older by a few years at least, although some batteries of any type can be killed quickly and are by some.

In your first post you said:

5. "For any given manufacturer, in most cases, the w-hr, volume, and weight of their GC2s and group 27s are virtually identical."

What you may be forgetting is the plate thickness. Nothing beats lead for longevity. If a group 27 is the same weight as a GC2 * the plates must be thicker in the GC2. The group 27 has 6 cells vs the GC2's 3 cells.

* Trojan's 105 AH group 27 (27TMX) weighs 55 lbs. Their T-105 weighs 62 lbs.

pcmm · 16-12-2016, 21:24

Quote:

Originally Posted by ramblinrod

Just did a search on Costco and Walmart sites, lots of 12 Vdc batteries, not one 6 Vdc. No Sam's Club in Canada. We do have Canadian Tire, a huge automotive / all house wares chain; lots of 12 Vdc / no 6 Vdc batteries listed.

Meanwhile, there are about 20 places in Peterborough (pop. 78,000) where I can buy 12 Vdc batteries. There are 6 Vdc batteries at TSC (I guess some old tractors had 6 Vdc starting systems). Are these quality deep cycle batteries? Prolly not.

A few marine retailers, within 100 mile radius stock 6Vdc batteries (Crown, Trojan, etc) but who knows how old they are, and they are super expensive. Do they even have enough to set up a 4 x GC2 house bank without having to order them in?

So just because 6Vdc batteries may be prevalent in some locales, don't assume you can get them easily anywhere; at least here it sure isn't so, and I've heard cruisers outside USA say they can't find them, when there are 12 Vdc batteries everywhere.

If you can't find GC2's in southern Ontario, then you're not looking Canadian tire has them on their website, TSC sells them, Costco sells them (their website sux). Every marine store I've been to sells them or orders them in. I can go on.

Keep in mode that probably 95% of grp27 batteries out there are starting batteries , different design than deep cycle. Also a grp27 typically is an 80ah battery vs GC2 at 220ah. So your typical bank of 4 GC2's would require at least 6 grp27 to have the same rating not 4.

mitiempo · 16-12-2016, 21:26

Quote:

Originally Posted by pcmm

If you can't find GC2's in southern Ontario, then you're not looking Canadian tire has them on their website, TSC sells them, Costco sells them (their website sux). Every marine store I've been to sells them or orders them in. I can go on.

Keep in mode that probably 95% of grp27 batteries out there are starting batteries , different design than deep cycle. Also a grp27 typically is an 80ah battery vs GC2 at 220ah. So your typical bank of 4 GC2's would require at least 6 grp27 to have the same rating not 4.

I agree. The GC2s we sell are 242 AH, for an even larger difference.

ranger58sb · 17-12-2016, 04:53

Quote:

Originally Posted by ramblinrod

Ratings vary by manufacturer, but for reasonable quality 12Vdc standard lead acid deep cycle batteries, they are somewhere in the neighbourhood of:

Grp 24 - 85 A-hrs
Grp 27 - 100 A-hrs
Grp 31 - 120 A-hrs

When I was shopping for our first bank of G31s -- 11 years ago, now, just getting ready to replace next season -- the Odyssey guy told me their 105 Ah rating (as published at the time) was more realistically 100 Ah... and I think since then they changed their publications.

I have assumed many of the manufacturers with smaller batteries were a bit adventurous with that rating thing... and if a pretty-good-quality G31 would give about 100 Ah, smaller batteries would likely offer less Ah, no matter who manufactured them. And I wanted as many Ah as I could get for that bank within the available space... not knowing much about GCs at the time...

So I didn't pay much attention to G27s, G29s, etc.

-Chris

ramblinrod · 17-12-2016, 14:45

Responses in Bold Red.

Quote:

Originally Posted by mitiempo

GC2s have virtually the same footprint as group 24 batteries. So as long as there is height available GC2s fit the same space. A pair of GC2s with 220 to 242 AH is a better choice for many than a pair of group 24s with 170 AH.

Trojan
Model W-hr Length Width Height Volume Weight
24 TMX 1020 10.92 (277) 6.62 (168) 9.25 (235) 669 ci 47(21)
27 TMX 1260 12.72 (323) 6.60 (168) 9.24 (235) 776 ci 55(25)
SCS225 1560 13.94 (354) 6.75 (171) 9.96 (253) 937 ci 66(30)
T105 1350 10.30 (262) 7.11 (181) 11.07 (281) 810 ci 62 (28)

So as we can see, comparing apples to apples, one manufacturer, the 6 Vdc battery in A-hrs, lies right in between the Grp 27 and SCS225. The consumed space (volume) is directly proportional, and the weight is higher.

So I don't doubt the Trojan T105 is a great battery. But I do doubt that it is that much better than the equivalent grp 27, and its a wash with the SCS 225 (heavier but lower W-hr rating).

Now here's a cheap no-name 6Vdc battery

GC2 1260 10.38 (264) 7.11 (181) 10.825 (276) 799 ci 58 (26)

See how the numbers match so closely to a Trojan 27 TMX?

So if there is so much extra lead, where is it? It doesn't weigh any more. Answer: There isn't more lead, it is just distributed differently. Not surprising, they are 6 Vdc batteries instead of 12Vdc batteries, having the same W-hr rating. Something has to be different. Does this make them last longer? There is no empirical evidence anywhere that indicates this is so.

Now, is it any where near the same quality?

Will it last any where near as long?

When one starts shopping products on price only, in my experience, they usually get pretty much what they pay for.

Think about it, since when does it make any sense for a manufacturer, distributor, and retailer to leave money on the table, selling something better for less money?

It may be that the purchase price of cheap GC2s is 50% of the Trojan Grp 27s, they have the same energy storage capacity, and they last half as long.

Where's the bargain? Savings today are costs tomorrow.

In this area - Victoria BC - GC2s are every bit as available as the 12 volt batteries. Costco, any dedicated battery retailer, as well as the store I work at - Trotac Marine. We sell a lot of 12 volt, mostly group 24 and 27, for small outboard and sterndrive boats as well as start batteries for larger power and sailboats. For house banks GC2s outsell all others by a wide margin.

We also take cores back, often only a couple years old if group 24 or 27. GC2's cores are in most cases older by a few years at least, although some batteries of any type can be killed quickly and are by some.

Yes I completely understand this. Because as I said, those who are using the grp 24 and grp 27 that came with the boat (house bank severely undersized) they are killing them prematurely because they don't know any better. Then they talk to a retailer who pushes GC2s, and are convinced to increase the size of the bank (w-hrs) and to take better care of their batteries and VIOLA they last longer (when in all likelihood they would have lasted longer had they upsized the 12 Vdc bank by the same amount and treated them better to the same degree.)

In your first post you said:

5. "For any given manufacturer, in most cases, the w-hr, volume, and weight of their GC2s and group 27s are virtually identical."

What you may be forgetting is the plate thickness. Nothing beats lead for longevity. If a group 27 is the same weight as a GC2 * the plates must be thicker in the GC2. The group 27 has 6 cells vs the GC2's 3 cells.

Absolutely, to produce the same W-hrs requires the same weight of lead. And a 3 cell battery producing 1200 W-hrs has to have thicker plates than a 6 cell battery producing 1200 W-hrs. Does the this make the 6 Vdc battery last longer? There is no empirical evidence to indicate so.

* Trojan's 105 AH group 27 (27TMX) weighs 55 lbs. Their T-105 weighs 62 lbs.

Yes, so the Trojan T105 is a better battery than the Trojan 27 TMX and the price reflects this. But the Trojan 12Vdc SCS 225 is a better battery than the T105, and the price is also reflected in this.

For other manufactures, as illustrated above, the grp 27 and GC2 is a much closer match.

My point is, the people buying the cheap GC2 think they are getting a steal of a deal, and I just don't think they are.

Someone posted that there are some 15000 golf clubs in the US. How many carts each, 50 avg ? Well there are 12000 marinas in USA. How many boats each, 200?

I really suspect that a whole lot of people are getting the wool pulled over their eyes, believing they are getting bargain 6 Vdc batteries, when in fact, they are getting exactly what they are paying for, and could be sticking with 12Vdc batteries, without the "pairing" problem.

pcmm · 17-12-2016, 16:24

Quote:

Originally Posted by ramblinrod

Responses in Bold Red.

My point is, the people buying the cheap GC2 think they are getting a steal of a deal, and I just don't think they are.

Someone posted that there are some 15000 golf clubs in the US. How many carts each, 50 avg ? Well there are 12000 marinas in USA. How many boats each, 200?

I really suspect that a whole lot of people are getting the wool pulled over their eyes, believing they are getting bargain 6 Vdc batteries, when in fact, they are getting exactly what they are paying for, and could be sticking with 12Vdc batteries, without the "pairing" problem.

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)