Battery Recommendations - Page 2 - SailNet Community

   Search Sailnet:

 forums  store  


Quick Menu
Forums           
Articles          
Galleries        
Boat Reviews  
Classifieds     
Search SailNet 
Boat Search (new)

Shop the
SailNet Store
Anchor Locker
Boatbuilding & Repair
Charts
Clothing
Electrical
Electronics
Engine
Hatches and Portlights
Interior And Galley
Maintenance
Marine Electronics
Navigation
Other Items
Plumbing and Pumps
Rigging
Safety
Sailing Hardware
Trailer & Watersports
Clearance Items

Advertise Here






Go Back   SailNet Community > General Interest Forums > Gear & Maintenance
 Not a Member? 


Like Tree5Likes
Reply
 
LinkBack Thread Tools
  #11  
Old 01-19-2013
RobGallagher's Avatar
HANUMAN
 
Join Date: Aug 2001
Location: Noank, Connecticut, USA
Posts: 1,306
Thanks: 7
Thanked 11 Times in 10 Posts
Rep Power: 13
RobGallagher is on a distinguished road
Re: Battery Recommendations

Quote:
Originally Posted by rbyham View Post
Thanks all. I will be in a wet slip with shore power. The boat aslo has a charger but I am not sure of make or model. The boat has no batteries at this point so I do not know what was there previous. But there are two cases and all wiring for two in the bilge and one battery case all wired to the Atomic 4 that sits in the port lazarette. So the cases and placement are set. All I need to do is drop batteries in and connect. The alternator is described as upgraded/over size but I have no idea how to determine what the level of output is. The boat is also wired for a solar panel. Wiring is there and controller but solar panel was toast. I plan to replace it but not sure how big that needs to be either. I will be using the boat basically for day sailing with the occasional weekend spent aboard.
It might help if you told us your location. Then again, it might not.

There is a great battery shop in Annapolis. Would that help?
__________________
HANUMAN
'88 C&C 30 MKII
NOANK, CT
Reply With Quote Share with Facebook
  #12  
Old 01-19-2013
chef2sail's Avatar
Senior Member
 
Join Date: Nov 2007
Location: Maryland
Posts: 6,706
Thanks: 23
Thanked 47 Times in 43 Posts
Rep Power: 7
chef2sail will become famous soon enough
Send a message via AIM to chef2sail
Re: Battery Recommendations

Quote:
Originally Posted by Oaksail View Post
I believe when you wire batteries in series you double the voltage but the amp hour capacity remains the same.
Eg. 2 x ( 6volt, 240 amp hour) = 12 volts at 240 amp hours.

When you wire batteries in parallel the voltage remains the same but the amp hour capacity doubles.

You don't get the same capacity in half the space with 6 volt batteries.
Ok let's try this again. 2 golf cart batteries (6 volts each wired in series) gives you 1 12 volt battery battery at 240 ah hours. It takes up the space of slightly more than 1 group 31 (12 volt batter) which give you 110 ah. For virtually the same space you get twice the ah and heavier plated batteries which if taken care of will give you more deep cycles.

If you buy 2 group 31 12 volts you now gt the same ah (240) as 2 golf cart 6 volt. If you make it eventually 4 golf cart 6 volt (first in series to make 2 12 volt batteries) then in parallel you would have 440 ah at 12 volts vrs the sames space 2 group 31 12 volt is 220 . The golf carts sit a little higher so you need to check that. It's a space savings to use the 6 volt golf carts plus more cycles.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
___________________________
S/V Haleakala (Hawaiian for" House of the Sun")
C&C 35 MKIII Hull # 76
Parkville, Maryland
(photos by Joe McCary)
Charter member of the Chesapeake Lion posse

Our blog-
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


“Sailing is just the bottom line, like adding up the score in bridge. My real interest is in the tremendous game of life.”- Dennis Conner
Reply With Quote Share with Facebook
  #13  
Old 01-20-2013
Oaksail's Avatar
Member
 
Join Date: Jan 2011
Location: Oakville, Ontario
Posts: 47
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 0
Oaksail is on a distinguished road
Re: Battery Recommendations

Quote:
Originally Posted by chef2sail View Post
Ok let's try this again. 2 golf cart batteries (6 volts each wired in series) gives you 1 12 volt battery battery at 240 ah hours. It takes up the space of slightly more than 1 group 31 (12 volt batter) which give you 110 ah. For virtually the same space you get twice the ah and heavier plated batteries which if taken care of will give you more deep cycles.

If you buy 2 group 31 12 volts you now gt the same ah (240) as 2 golf cart 6 volt. If you make it eventually 4 golf cart 6 volt (first in series to make 2 12 volt batteries) then in parallel you would have 440 ah at 12 volts vrs the sames space 2 group 31 12 volt is 220 . The golf carts sit a little higher so you need to check that. It's a space savings to use the 6 volt golf carts plus more cycles.
I don't see the physical numbers as you mention. I'm about to pull the trigger on adding 2 group 31 batteries to my house bank, but maybe i should reconsider.

Trojan T-125 - 6 volt 240 AH,
Weight: 66 lbs
Size (inches): L-10.38 W-7.13 H-10.88
Volume: 803 cu-in

Group 31 dimensions
L 13"
W 6-3/4"
H 9-3/8"
Volume 822.7 cu-in.

The advantage for the 6 volt is only 2.5% (803 cu-in / 822.7 cu-in.) however most group 31's are rated for 115 amp hour so 2 will give you 230. another 4% in favour of the 6 volt, but combined its only 6.5%

Am i missing something? I would love to get the capacity you're talking about.
__________________
1989 CS30
Reply With Quote Share with Facebook
  #14  
Old 01-20-2013
chef2sail's Avatar
Senior Member
 
Join Date: Nov 2007
Location: Maryland
Posts: 6,706
Thanks: 23
Thanked 47 Times in 43 Posts
Rep Power: 7
chef2sail will become famous soon enough
Send a message via AIM to chef2sail
Re: Battery Recommendations

Quote:
Originally Posted by Oaksail View Post
I don't see the physical numbers as you mention. I'm about to pull the trigger on adding 2 group 31 batteries to my house bank, but maybe i should reconsider.

Trojan T-125 - 6 volt 240 AH,
Weight: 66 lbs
Size (inches): L-10.38 W-7.13 H-10.88
Volume: 803 cu-in

Group 31 dimensions
L 13"
W 6-3/4"
H 9-3/8"
Volume 822.7 cu-in.

The advantage for the 6 volt is only 2.5% (803 cu-in / 822.7 cu-in.) however most group 31's are rated for 115 amp hour so 2 will give you 230. another 4% in favour of the 6 volt, but combined its only 6.5%

Am i missing something? I would love to get the capacity you're talking about.
No need to do the height, only length and width.

2- Group 31- 175 115 usable ah
2-Golf cart- 148 120 usable ah

3- Group 31- 262 172 usable ah

4- Group 31- 350 230 usable ah
4- Golf Cart- 298 240 usable ah

Remember you only get to use 1/2 of the usable ah. Thats why its important to do an electrical diet for a day. The big difference is when you get to 3 and 4 batteries.

Ours is almost 78 ah per day, but we have refrigeration ( 48 ah/day), chartplotter, but we have almost all LED lights now 9 .1 a/hr).

115 ah ( 2 group 31) can go quickly in one overnight or day of sailing. Also you engine will charge up to 85% 98 ah qwuickly but then will slow charge past there so most who use the engi8ne to charge dont get much above 85%. Different with a good 3 stage dock charger it can get back to 100% charge. Thats why I am saying you may want more capacity for peace of mind. Especially if you do more than one overnight.

My recommendation on the golfcarts were two fold. First the heavier plates give you more deep cycles therefore your battery will last longer. Second, if you decide to increase you capacity the space is considerably less (20%) when you get to having 220 usable amps.

For a boat which the diet is 70 ah like ours thats three days. For a boat with 40 ah/ day thats 5 days.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
___________________________
S/V Haleakala (Hawaiian for" House of the Sun")
C&C 35 MKIII Hull # 76
Parkville, Maryland
(photos by Joe McCary)
Charter member of the Chesapeake Lion posse

Our blog-
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


“Sailing is just the bottom line, like adding up the score in bridge. My real interest is in the tremendous game of life.”- Dennis Conner
Reply With Quote Share with Facebook
  #15  
Old 01-20-2013
Maine Sail's Avatar
Senior Member
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,130
Thanks: 8
Thanked 87 Times in 61 Posts
Rep Power: 15
Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice Maine Sail is just really nice
Re: Battery Recommendations

One thing not stressed enough is this does not take into account is the cycle life of a 12V flooded battery vs. a 6V flooded battery 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.

Beyond that on about 70% of the boats I work on "foot print" is the limiting factor and on about 30% height is the limiting factor.

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 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 hundreds of boats I work on. What I see is a 20 - 40% longer average life with 6V vs. 12V. I use the best analyzers, for field work, money can buy, one is $2000.00 and the other was about $800.00 plus I have many 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 that data you can always check with Trojan and ask them for the cycle life at 50% DOD for the marine SCS series of 12V batteries vs. the Golf Car line. It's all about cycle life..

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

That is DOUBLE THE CYCLE LIFE, per Trojan Battery.... The thicker plates, case design etc. do make differences. Remember that a 6V battery has 3 cells 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?

I don't see the 50% differences in the "real world" but I do see 20-40% longer life "on average" out of true deep cycle golf car batteries vs. 12V "marine style" batteries.

I measure this with industry standardized test equipment so this 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.

You can't just look at Ah capacity or box measurements you need to also look at cycle life... when you do the GC batteries make the most sense, IF YOU HAVE THE HEIGHT.....
ODay e-pod likes this.
__________________
______
-Maine Sail / CS-36T


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.




© Images In Posts Property of Compass Marine Inc.



Last edited by Maine Sail; 01-20-2013 at 01:57 PM.
Reply With Quote Share with Facebook
  #16  
Old 01-21-2013
rbyham's Avatar
Senior Member
 
Join Date: Dec 2012
Posts: 333
Thanks: 0
Thanked 7 Times in 6 Posts
Rep Power: 2
rbyham is on a distinguished road
Re: Battery Recommendations

Thanks all. This is helpful information. Simple works for me. So will go with the one 12v and 2 6v with the idea rthat this will get me started with option to add 2 6v. But PO had them in boxes in raised part of bilge so right on center line of hull. Sounds like a no-no here. Will try to relocate. I think alternator is 55amp, and charger is 3 stage. So should be good if I find right location. There is a perko on board as well.
Reply With Quote Share with Facebook
  #17  
Old 01-23-2013
asdf38's Avatar
Senior Member
 
Join Date: Jul 2010
Posts: 630
Thanks: 1
Thanked 3 Times in 3 Posts
Rep Power: 4
asdf38 is on a distinguished road
Re: Battery Recommendations

Quote:
Originally Posted by Oaksail View Post
I don't see the physical numbers as you mention. I'm about to pull the trigger on adding 2 group 31 batteries to my house bank, but maybe i should reconsider.

Trojan T-125 - 6 volt 240 AH,
Weight: 66 lbs
Size (inches): L-10.38 W-7.13 H-10.88
Volume: 803 cu-in

Group 31 dimensions
L 13"
W 6-3/4"
H 9-3/8"
Volume 822.7 cu-in.

The advantage for the 6 volt is only 2.5% (803 cu-in / 822.7 cu-in.) however most group 31's are rated for 115 amp hour so 2 will give you 230. another 4% in favour of the 6 volt, but combined its only 6.5%

Am i missing something? I would love to get the capacity you're talking about.
You're right and so is Chef. By volume there is little advantage but chef is pointing out that the GC batteries are taller and thus narrower which is often (but not always) better.

As to plate thickness that's the other advantage of GC batteries. Understand there is a tradeoff - thicker plates mean longer life but lower cranking amps.

There is some historical baggage to the labeling manufacturers use and typically a battery labeled "Marine Deep Cycle" is towards the deep cycle end of the spectrum, but not quite as far as a GC battery. This results in the unintuitive fact that GC batteries are actually better (longer lasting) in a marine deep cycle role than "Marine" batteries.

The spectrum looks something like this with starting on the left and deep cycle on the right:
Starting - Marine - Marine Dual Purpose - Marine Deep Cycle - Golf Cart/Floor Sweeper etc

From left to right you're losing somewhere around 40% of cranking amps, but gaining probably 4X-10X the deep cycle life. This is why I think it rarely ever makes sense to have a start battery on a boat - they're cheap one trick ponies and a deep cycle, for little extra cost gives you good cranking amps but much much better deep cycle life. And note that while starting batteries are quickly destroyed by deep cycling, deep cycle batteries are perfectly fine starting.

However, Chef, I really think it's inappropriate to simply say "GC batteries have more capacity for their size". That simple statement isn't true and leads to exactly the confusion Oaksail is expressing. Someone who is a bit skeptical, which is a good thing to be, is not going to believe that GC batteries offer something for free. Too often that's how it's presented around here. GC batteries are taller, and put out fewer cranking amps (rarely a concern), that's the trade-off that makes them "better" as a marine deep cycle battery.
mitiempo likes this.
__________________
1979 Contessa 26
Boston, Ma

Last edited by asdf38; 01-23-2013 at 12:55 PM.
Reply With Quote Share with Facebook
  #18  
Old 03-20-2013
T37Chef's Avatar
Senior Member
 
Join Date: Oct 2006
Location: Maryland
Posts: 3,954
Thanks: 16
Thanked 23 Times in 22 Posts
Rep Power: 8
T37Chef will become famous soon enough
Re: Battery Recommendations

Can I get absolute clarification please...

2 each Group GC2 6V batteries would equal 215 Amp hours, or about 105 usable a/h?

You do not get 215 a/h out of each.
__________________
Shawn
Tartan 37 - S/V Windgeist
Sailing the Chesapeake Bay


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Photo by Joe McCary
Reply With Quote Share with Facebook
  #19  
Old 03-20-2013
chef2sail's Avatar
Senior Member
 
Join Date: Nov 2007
Location: Maryland
Posts: 6,706
Thanks: 23
Thanked 47 Times in 43 Posts
Rep Power: 7
chef2sail will become famous soon enough
Send a message via AIM to chef2sail
Re: Battery Recommendations

Quote:
Originally Posted by T37Chef View Post
Can I get absolute clarification please...

2 each Group GC2 6V batteries would equal 215 Amp hours, or about 105 usable a/h?

You do not get 215 a/h out of each.
yes
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
___________________________
S/V Haleakala (Hawaiian for" House of the Sun")
C&C 35 MKIII Hull # 76
Parkville, Maryland
(photos by Joe McCary)
Charter member of the Chesapeake Lion posse

Our blog-
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


“Sailing is just the bottom line, like adding up the score in bridge. My real interest is in the tremendous game of life.”- Dennis Conner
Reply With Quote Share with Facebook
  #20  
Old 03-21-2013
chef2sail's Avatar
Senior Member
 
Join Date: Nov 2007
Location: Maryland
Posts: 6,706
Thanks: 23
Thanked 47 Times in 43 Posts
Rep Power: 7
chef2sail will become famous soon enough
Send a message via AIM to chef2sail
Re: Battery Recommendations

Quote:
Originally Posted by Oaksail View Post
I don't see the physical numbers as you mention. I'm about to pull the trigger on adding 2 group 31 batteries to my house bank, but maybe i should reconsider.

Trojan T-125 - 6 volt 240 AH,
Weight: 66 lbs
Size (inches): L-10.38 W-7.13 H-10.88
Volume: 803 cu-in

Group 31 dimensions
L 13"
W 6-3/4"
H 9-3/8"
Volume 822.7 cu-in.

The advantage for the 6 volt is only 2.5% (803 cu-in / 822.7 cu-in.) however most group 31's are rated for 115 amp hour so 2 will give you 230. another 4% in favour of the 6 volt, but combined its only 6.5%

Am i missing something? I would love to get the capacity you're talking about.
I look at it in 2 dimesions for fitting as height if it fits is irrelevant.

For my bank 6- 6 volts= 660ah ( 330 usable) 10.38X7,13X6= 444 sq in
6 group 31= 690 ah (345 usable) =13X6.75X6=526.5 sq in.

(526.5-444)/ 444= 18% space savings for virtually the same ah

330 ah usable and our diet is 78 ah/ day.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
___________________________
S/V Haleakala (Hawaiian for" House of the Sun")
C&C 35 MKIII Hull # 76
Parkville, Maryland
(photos by Joe McCary)
Charter member of the Chesapeake Lion posse

Our blog-
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


“Sailing is just the bottom line, like adding up the score in bridge. My real interest is in the tremendous game of life.”- Dennis Conner
Reply With Quote Share with Facebook
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

 
Posting Rules
You may post new threads
You may post replies
You may post attachments
You may edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Battery bank design recommendations prroots Electrical Systems 129 03-17-2011 04:59 AM
Battery Monitor - recommendations JLovett Electrical Systems 8 05-10-2010 07:24 AM
Any recommendations on a AGM starter battery for a 4 -108 Perkins? SanDiegoChip Gear & Maintenance 9 02-23-2010 10:55 AM
alternator and battery recommendations justonemoreproject Electrical Systems 11 02-25-2009 09:15 AM
Battery charge recommendations? killarney_sailor Gear & Maintenance 10 12-18-2007 09:20 PM


All times are GMT -4. The time now is 05:40 AM.

Add to My Yahoo!         
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
(c) Marine.com LLC 2000-2012