New Batteries

[Ken Juul]

A couple days ago I replace my house bank....4 6v gc2's from Sam's Club. Do I need to do anything to break them in?  They were on the charger about 30 hours before I left the boat.

[Stu Jackson]

Ken, suggest you look at the "101 Topics" thread, click on "Electrical 101", "Breaking in New Batteries" from the Ample Power Primer.  Some do that, others just use 'em. 

[jfssail]

Ken, I accidentally drained my new golf cart batteries the first week of service by leaving the frig on while we were gone for the week with the charger off. I recharged them at a low rate and they were fine for the following 8 sailing seasons.

Jack F Stewart
1993 C36 #1233 "Windancer"
Port Clinton, OH

[Indian Falls]

I need new house batteries also. 
Since I'm not cruising yet, I decided to go with two group 27 Napa batteries,  650 amp/hrs each for about 150$ for both. 
Someday maybe when these batts crap out, I'll be ready to travel, but til then this seems like the smarter more economical choice. 
A family member works for Napa so I get a small break on the price.

Any reason I should do different?

[mainesail]

Be sure you get the "deep cycle" version and not the dual purpose. Deep Cycle usually has a teal label and should have 575CCA. It is a 90Ah battery.  These batteries are made by Deka and are the identical battery as the ones sold as Sam's Club and West Marine and under the Deka brand.

650 is the CCA rating of the "dual purpose" battery but you want the deep cycle version...

[Indian Falls]

Thanks Ken.

In case I get a self appointed battery expert at the store... could you elaborate as to why I shouldn't use the dual purpose?  What would the dis advantages of the dual purpose be in a sail boat?  Other than easily starting big V8's in some boats...

[Ron Hill]

Dan : You need to do some homework on type batteries.

The internal plate design and arrangement are different for starting and deep cycle versions of batteries!!  That's why they are of a different design for starting (big initial load) and deep cycle (long time sustained load). 

There is no short answer to your question.  A few thoughts

[mainesail]

Thanks Ken.

In case I get a self appointed battery expert at the store... could you elaborate as to why I shouldn't use the dual purpose?  What would the dis advantages of the dual purpose be in a sail boat?  Other than easily starting big V8's in some boats...

The deep cycle batteries have thicker plates and are designed for deep discharges and long life. On sailboats we deep cycle batteries. A "dual purpose" battery is a compromise between a starting battery and a deep cycle best left for a bass boats. They will have shorter life in cycling applications.

There is absolutely no need on a small aux diesel to use anything other than a deep cycle battery, even for starting/reserve purposes. They just last longer.  These motors require very, very little from a battery to start.  

With two G-27 Deka deep cycle batteries, in parallel, you'll have 1150 cranking amps at ZERO degrees. If you are starting your motor at ZERO this means you'll still have about 4-5 times what your motor needs, even with deep cycle batteries... At 70F you'll be upwards of 1600+ cranking amps.

Starting batteries are made of very thin to thin plates to deliver quick bursts of current out of "small" battery cases for starting. When asked to provide current for long durations the peter out quickly and die sooner. These batteries do not last very long at all when used for cycling.

On the other hand deep cycle batteries can do both very well especially on a Catalina 34... You get a lot more bang for your buck with a deep cycle battery. Plus with two group 27's you'll get 20 more Ah's of capacity with the deep cycle vs. the dual purpose..

[Indian Falls]

The short answer is:  $75 bucks each!    But this is about Mainesails' statement, not my homework.

Mind you, it was Mainesail who pointed out that the Dual purpose deep cycle is a bad choice over the standard Napa DEKA deep cycle... I just wanted to know why he pointed that out if they are both deep cycle batts?.  
He inferred that he knew something about not using the Napa dual purpose but really didn't mention the reason.  

That's why I asked him to elaborate.

This forum is for the exchange of information, lets not forget...

[Indian Falls]

By the way there is a short answer to my question about the dual purpose vs the deep cycle and it is simply this:

The dual purpose does not like to be discharged below 50% where true deep cycle can be discharged to 80%.
This would happen more often than not on a sail boat and reduce the life of a dual purpose battery significantly.

The second part of this question is cranking amps:  With two group 27's able to put out more than 1400 crank amps at 32F, it's not even a consideration.


Now when I go to the store and the "self appointed battery expert behind the counter" tries to talk me into the dual purpose I won't be easily swayed.

[mainesail]

By the way there is a short answer to my question about the dual purpose vs the deep cycle and it is simply this:

The dual purpose does not like to be discharged below 50% where true deep cycle can be discharged to 80%.
This would happen more often than not on a sail boat and reduce the life of a dual purpose battery significantly.

The second part of this question is cranking amps:  With two group 27's able to put out more than 1400 crank amps at 32F, it's not even a consideration.


Now when I go to the store and the "self appointed battery expert behind the counter" tries to talk me into the dual purpose I won't be easily swayed.

No battery likes to be discharged to 80% DOD and this is why the manufacturers all recommend 50% DOD except Li and TPPL manufacturers. If you want to get your moneys worth out of your batteries do not cycle them below 50% on a regular basis and charge them to 100% as often as possible. Trojan, Deka, US Battery, Exide, Johnson Controls, Rolls, Lifeline, Crown etc. etc. etc.all recommend 50% DOD as max discharge for cycling applications.

Can the batts be cycle to 80% DOD? Sure, but you lose cycle life by doing so. Lifeline initially recommended 80% DOD for their AGM batteries and it bit them in the arse quite hard. They now advise 50% DOD..

That said a deep cycle will ALWAYS last longer than the same battery in a Dual Purpose, in the same situation, because the plates are thicker. Thicker plates mean longer life.. This is also why a 6V deep cycle battery battery will outlast a 12V deep cycle bank of the same rated Ah capacity. The 6V battery has significantly thicker plates and thus lasts longer given the same treatment.  


One thing I don't see talked about often enough is taking cycle life of a 12V flooded battery vs. a 6V flooded battery into account, when put in the same deep cycling application. The 6V batteries will outlast the 12V. I find on average 20-40% more life in the real world with 6V batts vs. 12V.

On about 70% of the boats I work on "foot print" is the limiting factor and on about 30% height is the limiting factor. Can't recall if 6V fit on a C-34 but I think they do?

GC2 / T105 size golf cart batteries are closer in foot print to a group 24 than a 27 or29/31 and with foot print usually being the constraint limit, more so than height, one must consider foot print comparisons vs. weight or box volume...

GC2 / T105 = 10 3/8" Long by 7 1/8" Wide by 10 7/8" Tall
Group 24 = 10 3/4" Long by 6 13/16" Wide by 8 11/16" Tall
Group 27 = 12 9/16" Long by 6 13/16" Wide by 8 3/4" Tall

If we compare the Deka / Duracell brand from Sam's Club (same as West Marine)

EGC2 6V = 230Ah for 2 batteries
Deep Cycle Group 24 12V = 150Ah for 2 batteries

The 6V batteries, in the same basic foot print of a group 24 have 80Ah more capacity for two, or nearly an entire group 24 battery...

I have piles of boats I work on to see these differences. What I see is a 20 - 40% longer average life with 6V vs. 12V. I use the best analyzers, for field work that money can buy. One analyzer is $2000.00 and the other was about $800.00 plus I have other means of testing too.

The Midtronics tool is the one battery manufacturers use and supply to distributors like West Marine, Wal*Mart & Sam's Club for warranty claims.

Beyond what I see you can always check with a company like Trojan and ask them for the cycle life at 50% DOD for the marine SCS series of 12V batteries vs. the Golf Cart line. It's all about cycle life not necessarily Ah's.....

What Trojan will tell you is that the SCS, at 50% DOD, is rated by Trojan at 600 cycles and the golf cart batteries, like the T105, are rated at 1200 cycles!!! Of course these are "lab" numbers and you'll likely never see that in the "real world" but you will see longer life out of a 6V golf cart battery vs. 12V in the same application. Just like you'll see more cycles out of a 12V "deep cycle" vs a 12V "dual purpose"...

Keep in mind with the Trojan example that this is DOUBLE THE CYCLE LIFE when comparing their marine 12V to a 6V battery..... The thicker plates, case design etc. do make differences. A 6V battery has only 3 cells in the case and weighs 66 pounds vs. the 12V battery having 6 cells and weighing the same. Which battery has the thicker plates? The one with 3 cells or the one with 6 cells?

While I don't see the 50% differences in the "real world" I do see 20-40% longer life "on average" out of true deep cycle golf car batteries vs. 12V "marine style" batteries. If the option exists 6V batteries are much less expensive over the life of the battery.

I get to measure this with industry standardized test equipment so what I see is not just a "shoot from the hip" thing... The differences are real, quantifiable and measurable differences and also backed up by companies like Trojan battery in their own in-house testing.

Unfortunately you can't just look at Ah capacity or box measurements or even Ah capacity to determine "value" you need to also look at cycle life over the long haul... A dual purpose has less than a deep cycle and a 12V deep cycle has less than a 6V deep cycle...  When you run the numbers out the golf cart batteries make the most sense, if you have the height.

[Mick Laver]

Mainesail - Yes, 6V "golf cart" batteries will fit in a C34 quite nicely. In fact I'm about to replace my 9-year-old Trojan T105s with Lifeline GPL-6CT 6V AGMs. One of the main reasons I'm going with AGMs (other than maintenance and safety issues) was the deeper discharge cycle, but now you're saying Lifeline also recommends 50%? Since the AGMs are much more expensive (~4x) than flooded I'm starting to wonder if the marginal additional hassle of dealing with flooded batteries justifies the additional cost!

[Stu Jackson]

Mick, IMHO AGMs are simply not worth it.  In the "Electrical 101" topic (under the "101 Topic" sticky), there is a link to a discussion by Maine Sail called "darned AGMs" that you might be interested in reading.

AGM Battery Issues (from Maine Sail) 
http://forums.sbo.sailboatowners.com/showthread.php?t=124973

AGM Battery Issues and the Blue Seas Dual Circuit Switch (from Maine Sail) "DARN AGM Batteries"
http://forums.catalina.sailboatowners.com/showthread.php?p=848465&highlight=darn%20agm

[Ron Hill]

I know that there are some people that don't like the AGM batteries, but it's interesting that the AGMs seem to have a longer warrantee?!

[mainesail]

I know that there are some people that don't like the AGM batteries, but it's interesting that the AGMs seem to have a longer warrantee?!

Please keep in mind that the pro-rata portion of any battery manufacturers warranty is really not worth the paper it is written on. I personally therefore really only care about the free replacement period. That said any battery that can't make it through the free replacement period is pretty poor. BTW you are paying for the longer warranties periods whether you choose to or not...

Lifeline AGM = 12 Month free replacement (Rated cycles at 50% DOD = 900)

Wal*Mart flooded battery = 18 month free replacement.


Optima:
AGM - 24 Month free

Odyssey:
AGM - 24 Month free (Rated cycles at 50% DOD = 700)

Deka: (the largest volume producer of AGM batteries for marine applications)

Flooded = 12 Months free (Rated cycles at 50% DOD = 800)
AGM = 12 Months free  (Rated cycles at 50% DOD = 500)
GEL = 12 Months free (Rated cycles at 50% DOD = 1000)

Rolls Battery:

Flooded:
4000 Series 24 Months Free - (Rated cycles at 50% DOD = 1300)
5000 Series 36 Months Free - (Rated cycles at 50% DOD = 3200)

AGM = 24 Months Free - (Rated cycles at 50% DOD = 1000)

US Battery:
Flooded = 12 Months free (Rated cycles at 50% DOD = 1150)
AGM = 12 Months free (Rated cycles at 50% DOD = unpublished)