4D batteries / 8D - "true" deep cycle (or not)?

[KWKloeber]

Gang,

I have read here and elsewhere about 4D's (and 8Ds) being not "true" deep cycle. 

My bro has Deka/East Penns, 8D - listed as deep cycle, but am wondering -- are all or most 4Ds/8Ds inherently not "true" deep cycle-ers, or is just certain brands (possibly manufactured with less that "adequate" plates)? 
For instance the C355s come with Exide Gold 4D,  but I have read on forums that they are not "true" deep cycle.

Cheers,
Ken

[Stu Jackson]

From a search on "not deep cycle" by Maine Sail on co.com:


http://forums.catalina.sailboatowners.com/showthread.php?p=795574&highlight=not%20deep%20cycle

[KWKloeber]

Thanks Stu,

I wan to SBO and mused the question to RC..  We'll see what/if he comes back with.

Cheers,
Ken

[Stu Jackson]

Here's the text of Maine Sail's reply (at the bottom of that link - photo didn't come through):

I will let Deka's own data speak for itself....

NOTE: Only ratings within a brand /manufacturer are useful. Cross brand cycle life data is useless because there is no industry standard for testing. Actually there is, but no one seems to want to use it. Most all of them are fantasy level data when applied to real world marine use. Only in-house manufacturer testing across their own batteries can be compared for guidelines.

Why? Because all battery manufacturers assume & recommend that you recharge to 100% SOC after each deep discharge. They expect this to be done immediately. The sad reality is with sailboats this does not always happen. We wind up using batteries that were never intended for partial state of charge operation in a PSOC environment which results in considerably less cycles than what the manufacturers "lab" data suggests could potentially happen.


Deka / East Penn Battery Data By Type:

-GEL Cycles to 50% = *1000 Cycles
-6V Flooded Golf Cart Batteries Cycled to 50% = *700-1000 Cycles
-12V Deep Cycle Flooded Cycled to 50% = *350 Cycles
-AGM Cycled to 50% = *300 Cycles (includes 4D & 8D)

*NOTE: These are not what you will see in the "real world" except for the possibility of GEL.....

That is not my data but Deka's own data across their own batteries.... As can clearly be seen;

*They rate their 12V DC wets at 50 more cycles than AGM.
*They rate their 6V DC wets at 400 - 700 more cycles than AGM
*They rate their GEL batteries at 700 more cycles than AGM...

Lifeline does make a "deep cycle" 4D or 8D but Deka does not, unless you consider 300 cycles "deep cycle". Beyond that AGM's are quite picky about proper use and charging. Done right, and for the right reasons, they are good batteries. Done wrong and for the wrong reasons they are a massive hole in your wallet.

For the life of me I do not understand why anyone would pay 2¢ for an 8D or 4D unless you were trying to start a massive diesel in a sport fishing yacht.. Even the big OTR truck manufacturers have moved to parallel group 31's and some battery makers, such as US Battery, have even stopped making them all together......

Scenes like this on OTR trucks are becoming the norm and 4D and 8D's once the norm here are a dying breed. This a bank of three Group 31 Odyssey TPPL AGM batteries.


In summary the term deep cycle has been bastardized in the industry and is basically a bunch of bovine dung when used to describe typical 4D, 8D, Group 24, 27 & 31 12V batteries.

__________________
____________
-Maine Sail / CS-36T

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[mainesail]

Gang,

I have read here and elsewhere about 4D's (and 8Ds) being not "true" deep cycle. 

My bro has Deka/East Penns, 8D - listed as deep cycle, but am wondering -- are all or most 4Ds/8Ds inherently not "true" deep cycle-ers, or is just certain brands (possibly manufactured with less that "adequate" plates)? 
For instance the C355s come with Exide Gold 4D,  but I have read on forums that they are not "true" deep cycle.

Cheers,
Ken

Most all flooded 4D & 8D batteries are all dual purpose or starting. Dyno does claim to make a deep cycle version but they are a very small West Coast company.. Many of these batteries do get marketed as deep cycle but it is marketing mumbo jumbo not a real deep cycling battery.

Also keep in mind that Group 24, 27 & 31 batteries are also not a true deep cycle battery in flooded designs. When compared to their sister cases, in starting or dual purpose, they appear to be "deep cycle" but when compared to a true deep cycle battery, such as a GC2 6V or a GEL battery they are not at all deep cycle. Trojan for example rates their entire 12V SCS line up at just half the rated cycles of their T105. Half the rated cycles!! What's the better value, 200Ah's of Trojan 12V batteries or 200 Ah's or Trojan 6V batteries? What's the better value a Deka GEL battery rated at 1000 cycles vs. a Deka AGM rated at 300 cycles? Even if the GEL cost $50.00 more this is a steal.

Most G-24, 27, 31, 4D & 8D 12V flooded batteries are all "imposters" including Trojan 12V G-24, G-27 & G-31... Some will give more "cycles" than others in these group sizes but none compete directly with a true deep cycle battery such as a GC2 6V in terms of cycle life..

Battery buyers should always understand they are are not just buying Ah capacity they are buying expected cycle life too.

There are 12V golf cart batteries such as the Trojan T1275, and they do have the same cycle life as a 6V, but they are also taller, like the 6V, and a built to use the same plates as a GC2 battery. They are also pretty darn pricey compared to T 105's due to volume..... G-24, 27 & 31 batteries simply do not have the plate thickness a GC2 battery does because they are adapted battery case sizes from the 1950's automotive world......

For example in the Deka / Sea Volt / West Marine line you have starting, dual purpose and deep cycle G-24, 27 & 31 12V batteries which all share the same case. However they are only really deep cycle when compared to the starting or dual purpose batteries which share the identical case. They are not "deep cycle" when compared to the GC2 or other true deep cycle batteries. Deep cycle? Compared to what? This is what needs to be asked....

Here's the data across the Deka / East Penn / West Marine line up:

Flooded Batteries - Group 24, 27, 31 4D, 8D & 6V GC2

12V Starting - Cycles to 50% = Not Rated
12V Dual Purpose - Cycles to 50% = 200 (4D & 8D)
12V Deep Cycle - Cycles to 50% = 350 (G24, 27, 31)
6V Golf Cart - Cycle to 50% = 700-1000 (GC2 cases)

*Note: The above are LAB RATED cycles. Expect less in the real world..

As can easily be seen the 12V "deep cycle" battery is only a "deep cycle" when compared to the starting or dual purpose batteries it shares a case with. If you absolutely must buy a 12V G-24, 27 or 31 buy the deep cycle version. In many cases this is all that will fit. It is easy to see that these are NOT deep cycle when compared to a real deep cycle battery. If you feel the urge to buy a 4D or 8D, don't as there are much better choices......

The only ones that have lab rated cycles the same or close, to their own brands 6V batteries, are Lifeline AGM's. I know of no other brand that will rate their G-24, G-27 or G-31 at even half the cycles of their GC2 6V batteries. The Deka / East Penn / WM product is less than half...

It should be noted that West Marine, for all the crap they take, is actually honest in their labeling of the Deka 4D and 8D flooded batteries and they don't lie and call them deep cycle. This is more than I can say for a LOT of the private labeled Deka/East Penn product.

Again the term "deep cycle" has been grossly bastardized, diluted and abused by the marketing teams. A Deka AGM at 300 cycles is not what I would consider a deep cycle battery. A Deka GEL at 1000 cycles IS a deep cycle battery, I have one GEL bank that just entered its 15th season!! The 6V GC2 at 700-1000 cycles or L-16's etc. are also true deep cycle batteries.

Remember its not just Ah capacity you are buying...!! Cycle life is where the returns are...