Light Cycle vs. Deep Cycle
If you've been reading my stuff for any length of time you'll know I like to look inside things, cut them open and autopsy them. Batteries have not escaped my fascination with power tools.
Right:
On the right we have a 235Ah GC2 6V golf cart battery. There are three cells in total and some nice room in the bottom of the case to catch any shed sulfate (think dead skin cells). The plate separators are a nice heavy rubber-like material. Batteries can occasionally short internally as shed sulfate piles up under the positive and negative plates. Once it builds up enough to touch we now have a cell that self discharges due to contact between a positive and negative plate.... The positive plates on this battery measured 0.121" or just shy of 1/8" thick.
Left:
Here we have another re-branded sticker shop Group 24 "Deep Cycle" battery. This one is actually manufactured by Exide and sold as a "Marine Deep Cycle"... Sure, if you say so. (grin)
Wow!!!
"Where's the beef?"
No I am not kidding. This photo reminds me of the Wendy's commercial from the early 80's with the little old lady asking "Where's the beef?" Laugh all you want but both of these batteries are sold & marketed as "Deep Cycle". The only ones laughing are the battery makers, all the way to the bank, with YOUR money. Which one would you rather lay your hard earned money down on....???? Which one do you suppose is really capable of deep cycling...?
î
One glaring dissimilarity between these two batteries, besides the lack of lead on the 12V Group 24 pseudo deep cycle battery, is that this pseudo battery has very, very minimal room under the plates for any shed sulfate to collect. Also note how much battery case is wasted on-top of the plates.... Big box, hardly any lead while the golf cart battery is a taller box crammed chock full of lead. Both batteries take up virtually the same amount of floor space or foot print.
The big differences between the 12V deep cycle and the 6V deep cycle are more cycles, less cost per Ah, less cost per cycle and at the slight impact of a bit more height to fit the golf cart battery. If you have the height why would you use a more costly yet inferior product..?? Should a Yugo cost MORE than a Lexus? Would you pay MORE for a Yugo than you would for a Lexus? No, of course not, so why do that with marine batteries?
Plate Thickness:
6V GC2 235Ah = 3.07 mm (0.121") or just shy of 1/8"
Group 24 12V = 1.57 mm (0.0617") or just shy of 1/16"
Please remember the plate thickness of this group 24 "deep cycle" battery when you scroll down. This "sticker shop deep-cycle battery" has plates that are actually thinner than the starting battery pictured below and plate heights equivalent to the starting battery. Why? Because this is NOT A DEEP CYCLE BATTERY! The sticker is simply a lie....
NOTE: Used plates have a tendency to "swell" a bit beyond the as new factory specifications. The GC2 battery factory specification is 0.110 for the positive plate, a measured 0.011" variation from spec, and the Group 24 plate thickness is "unpublished", go figure.
You actually did read that correctly, the golf cart battery is almost double the positive plate thickness. Sometimes a picture is worth a thousand words, this one might be worth 1500.... (wink)
As I say repeatedly to my customers and consults clients; "Deep cycle is often just a sticker, know what you are buying."....
What About a "Starting" Battery?
This is one of the very few marine batteries I have replaced due to being chronically over charged. The owner of a center console placed an unregulated 15W solar panel on his T-Top and fed it directly to his East Penn/West Marine starting battery. About 9 weeks later the battery shorted internally due to crumbling plates and refused to start the vessel.
Look at the bottom of the battery case and notice how close the positive & negative plates are to the plastic. When the plates started crumbling, due to chronic over charging, brittle flaking lead fell to the bottom and created an internal short. The end cell, closest to you, was the shorted one.
On the left you can also see how brittle the lead grid/plates had become.
Starting vs. Pseudo Deep Cycle
On the left is the starting battery that was cooked do to unregulated solar charging. On the right a pseudo deep cycle destroyed in less than one season by deep cycling, charging with only an automotive type alternator & PSOC use.
The Kirkland (Johnson Controls) "deep cycle" battery (on right) was brand new in May of 2015 (date code) and put into actual service in July. By October the battery was only delivering 28.2 Ah's from its 115Ah factory rating! This battery was in parallel with a sister battery and both tested nearly identically. Let me sum this up......
THESE ARE NOT DEEP CYCLE BATTERIES!!!!!
Long and short I cut both of them open to expose the internal construction......
The Stickers
Here I have flipped the G-27 batteries around showing the stickers. I also laid out from L to R the negative plate, positive plate and the separators.
The West Marine battery is one of their highest CCA batteries and the Kirkland is anything but a "deep cycle" despite what the BS on the sticker says.
We often hear how different starting and "deep cycle" batteries are and when comparing a true deep cycle product to a starting battery there are definitely some major differences. In the case of these two batteries however the construction is more similar than different.
--Plate Separator Envelopes = Same Quality/Virtually Identical
--Negative Plates = Virtually Identical Thickness
--Positive Plates = Virtually Identical Thickness
--Plate Size = Deep Cycle Has Taller Plates
--Number of Plates = Starting Battery Has One More Plate Pair Per Cell
Deep Cycle G-27 Positive Plate Thickness
So how do they compare:
Deep Cycle G-27Battery:
-- Larger Plates (taller)
-- 6 pairs of positive & negative plates in each cell
-- Positive Plate Thickness = 2.15 mm Thick (0.085")
Starting G-27 Positive Plate Thickness
So how do they compare:
Starting G-27 Battery:
-- Smaller Plates (shorter)
-- 7 pairs of positive & negative plates in each cell
-- Positive Plate Thickness = 2.20 mm Thick (0.087")
Let's break it down;
For years and years all we've heard is;
"Starting batteries have many more and much thinner plates".
Really?
The plates in this starting battery are actually 0.05 mm thicker than the deep cycle battery. While the cells are smaller in physical size they did cram one more positive and negative plate into the starting battery in order to deliver a slightly higher CCA rating.. This hardly qualifies as "many more plates and thinner plates".
While these two batteries are from different manufacturers they all mislead the consumer. Sure, the plates are taller on the deep cycle but the positive & negative plates are virtually the same exact thickness on the starting battery as they are on the deep cycle.
This "deep cycle" Kirkland battery lasted less than 35 real-world deep cycles. After those cycles it could barely muster 28 Ah's of accurately tested capacity.
Is this Costco/Kirkland/Johnson Controls battery really a deep cycle battery just because the sticker says so? If you think it is please call me, I have a bridge that's a killer deal...(wink)
Distributor Level Branding
Many regional battery distributors, or "Sticker Shops" as I call them, re-label batteries to create more market share for a particular brand/manufacturer of battery.. The most often re-labeled batteries for marine use are Deka /East Penn, Johnson Controls, Superior and a few others.
The labels slapped onto batteries are occasionally not at all representative of the battery physically wearing the sticker.
For example I have seen many marine batteries that are actually 4D or 8D starting batteries labeled as either deep cycle or dual purpose. I have also seen 4D & 8D dual purpose batteries labeled as deep cycle. West Marine is at least honest in their labeling of the Deka / East Penn 4D & 8D flooded batteries and they call them Dual Purpose.
Here is a good hint, there are only two companies I know of building a true "deep cycle" 4D or 8D flooded batteries and those are hand made by Dyno Battery up in Washington state & Rolls in Nova Scotia Canada.. Any other flooded 4D or 8D, no matter what the sticker says, is not a true deep cycle battery. Just because they are big and heavy, don't be fooled by the sticker unless you pay the premium for a Dyno or a Rolls..
Regional Distributor "Sticker Shop" Issues:
Not to pick on Ultra Power, which are stickered up by a regional battery distributor, but it appears that when shipments get delayed, or stock gets low, I can occassionally find the same rating / specifications sticker on different batteries made by entirely different manufacturers!!! Scary stuff I know!!
Back in 2009 I had a customer with two Group 27 "Deep Cycle" Ultra Power EV27 "sticker shop" batteries. One was apparently physically made by Deka / East Penn and the other apparently by Johnson Controls. These batteries (pictured) were in a parallel bank and were flat-ass dead in under 2.5 years.
Despite being different products, manufactured by two different companies, both batteries had the same deep cycle specifications of 110Ah on the Ultra Power sticker. Deka to my knowledge has not manufactured a 110Ah deep cycle Group 27 marine battery.. Odd at best....
Look very closely at these two batteries, bought the same day, at the same vendor and labeled identically. The cases are not even close to the same design, the terminals are different, the handles are different, the caps are different and they are likely not both 110Ah batteries.
Caveat emptor when buying sticker shop batteries...
P.S This installation is not and was not my work!
Distributor Level Mislabeling
Here again we have two batteries wearing the same distributor level specifications, and stickers, but they tested differently, when brand new, and were so far apart as to not even be in the same ball park. Heck based on case identification marks they don't even appear to be made by the same manufacturer. Coincidentally the specification stickers suggest they are identical batteries....
Distributor branding = BUYER BEWARE!!
Deep Cycle 12V Group 24 vs. 6V GC2
Why 6V 0r 12V Golf Cart or Industrial Batteries?
#1 They are more durable and longer cycling than 12V Group 24, 27 & 31 marine batteries. They are designed for the rigors and abuses of golf carts and were designd from the ground up as a deep cycling product, not "adapted" from automotive use.. They are simply more robustly built often with better separators and always with more lead and thicker plates. While thicker plates do not always make a battery deep cycle when talking 6V or 12V Golf Cart batteries, compared to typical 12V Group 24, 27 & 31 this is a truism.
#2 They have considerably longer cycle life than 12V flooded light-cycling batteries and even in the real world this tends to translate out to approx one third to double more the life of the average 12V flooded battery.
#3 You can fit more Ah's in a smaller foot print but they do require some additional height..
#4 Price wins! Ignore the West Marine pricing and shop other places. You'll see the cost per Ah and per cycle between 12V flooded batteries and GC2 6V or even GC12 golf cart batteries becomes even more apparent. The GC2 230Ah battery pictured at the top of this article can also be purchased as a Duracell EGC2 at about half the Sam's Club's in the US. This means $109.00 at Sam's vs. $199.99 at West Marine. The only difference between these two batteries is the sticker that East Penn installs at the factory.
Take a close look at the foot print of these two 6V GC2 batteries take up compared to two Group 24 deep cycle batteries. The only sacrifice you need to make, to get all the benefits of golf cart batteries, on your boat, is a little more height to fit the GC2's.
Don't Limit Yourself
Don't limit yourself to just the typical deep cycle batteries you may find at a chandlery or marine store. This is a 400Ah bank consisting of two Trojan L16 size 6V batteries. While L16's are much taller than 12V batteries, or even GC2 6V batteries, they take up less foot print. For this owner he had the height but not the foot print. These two batteries are sitting where two Group 27's used to be and he now has 400 Ah's vs. approx 180 in the same foot print.
"But RC what if I don't have the height to fit actual deep cycling batteries?"
There are a few way's to look at this:
#1 Accept your limitations, accept the marketing is misleading and just stick with a premium quality "light cycling" G-24, 27 or 31 flooded battery such as a Crown, Trojan, US Battery and replace it when it dies. Rolls actually makes a fairly deep cycle G 27 & 31, though not quite the same as their GC2's but closer than most, however they are God awfully expensive.
With good care in a coastal cruising application light cycling batteries can still certainly deliver an acceptable life for the cost outlay. If you practice good battery care you may be able to eek out another 6 months to a year beyond where you are now. Cost is minimal & no modifications. Upgrade cost = $
#2 Move to a premium AGM (Lifeline, Odyssey, Northstar) or GEL (Deka, Trojan or Sonnenschein/Prevailer) battery. In the G-24, 27, 31 4D & 8D both premium AGM and GEL are deep cycle. AGM's & GEL's are arguably a bit temperamental in how they are cared for and charged and these really need to be installed as a "system". The charging system upgrade costs can far exceed the cost of the batteries. These batteries are simply too expensive to not install correctly. Done correctly AGM can often approach 6V GC2 life and GEL's often exceed it. Of course, like anything, there are always outliers. You can murder expensive AGM's & GEL's just as fast as pseudo batteries if the system & use is not done correctly. GEL batteries are pretty much the hands down kings of small case cycle life. The Deka GEL is rated at 1000 cycles. I have a number of GEL banks out there well beyond ten years and one into its 15th. My friend Bruce went around the world TWICE in the same set of GEL batteries..... Upgrade cost = $$$$$
#3If you are going to be doing some serious cruising, consider relocating your house batteries and fabricate / build a new space for them. You can leave the starting battery as a deep cycle pseudo type, in the original location, and just revamp the house bank. Upgrade cost = $$
Some times when you factor in how long you plan to keep the boat, sticking with light cycling batteries, despite the hit in cycle life, it may win the value game.
14-APR-2015
There are Also 12V Golf Cart Batteries
If you are uncomfortable wiring 6V you can always purchase golf car durability in a 12V battery.
The battery on the left is a golf car 12V battery. This Duracell GC12 is purposely placed next to a Group 31 12V battery. While it's certainly taller they will usually fit where a Group 31 did and often a where Group 27 did. The BCI group size of GC12 is far too often over looked in the marine industry.
GC12 batteries are usually between 145Ah and 155Ah in a 12V case:
Deka / East Penn = GC12 (the Duracell pictured is an East Penn GC12)
Crown = CR-GC150 or CR-GC155 (Crown's are very attractively priced)
Trojan = T1275 or J150
Interstate = 12VGCUTL
US Battery = US 12VE XC2 or US12V XC2
Once Again the deep cycle *GC12 wins the price battle over a "light cycling" battery.
GC12V - 150Ah = $167.25/$1.12 Per Ah > 1200 50% DOD Lab Rated Cycles
Group 31 - 130Ah $159.95.00/$1.23 Per Ah > 525 50% DOD Lab Rated Cycles
2 X GC12 = 300Ah @ $334.50 > 1200 Lab Cycles
@ X G31 = 260Ah @ $319.90 525 Lab Cycles
My local distributors pricing within the same brand.