Changing 6V to 12V Batteries - 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 > General Discussion (sailing related)
 Not a Member? 


Reply
 
LinkBack Thread Tools
  #1  
Old 10-25-2010
Junior Member
 
Join Date: Aug 2010
Posts: 23
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
kevandraper is on a distinguished road
Cool Changing 6V to 12V Batteries

Hi,
Am thinking of replacing the current old 6Volt batteries and putting in 12Volt. Are there any issues with doing this. Don't really understand why some yachts have 6V and others 12 volt. Are there any benefits with either. The current batteries are wet cell, have read the posts regarding the use of AGM;s and it appears to make sense staying with wet cell. I live aboard and have solar, 110 high output alterntor and will shortly fit an Airex wind generator. Will be taking off on a long term cruise in february. I aim to have 500-600amps storage, do you think this is sufficent. Don't know what my daily draw would be but the yacht is fitted out with all the normal cruising gear Any comments or advice would be much appreciated.
Reply With Quote Quick reply to this message Share with Facebook
  #2  
Old 10-25-2010
Member
 
Join Date: Feb 2007
Location: aboard, Malaysia
Posts: 73
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 8
klubko is on a distinguished road
6V batteries have more cycles so might last longer. I don't think there's anything else to worry about. Is 500-600amps enough? We have 200amps and we are quite happy, of course our biggest consumer is notebook and we are in the tropics with two 40W solar panels and Air-X. Rarely do we need to start the engine to top up.
__________________
Petr & Jana
s/y Janna, HR 31 Monsun

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Reply With Quote Quick reply to this message Share with Facebook
  #3  
Old 10-25-2010
Senior Member
 
Join Date: Apr 2000
Location: San Pedro, CA
Posts: 266
Thanks: 0
Thanked 1 Time in 1 Post
Rep Power: 15
windward54 is on a distinguished road
If you are sticking with wet cell batteries anyway, you might want to think about keeping the 6 volt batteries. They are built to discharge and recover, but I found the biggest benefit is the weight. It was a lot easier to lift two, 6-volt batteries, one at a time than the 12 volt battery.
Reply With Quote Quick reply to this message Share with Facebook
  #4  
Old 10-25-2010
Maine Sail's Avatar
Senior Member
 
Join Date: Jan 2003
Location: Maine Coast
Posts: 5,540
Thanks: 13
Thanked 150 Times in 116 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
The 6V wet cell battery is a tried and true work horse, if you have the space, height wise. There is no good reason to switch from 6 6V to 6 12V batteries. The 12V will usually not last as long, will generally cost more and will take up more foot print to get the same number of Ah's. The only time I will use 12V batts for a house bank is if I only have space for an odd number of batteries. For instance if you only have space for three batteries then three 12V deep cycles will give you the most Ah's for the space constraints, as you would need two or four in 6V to do the same thing. The entire golf car industry and industrial machine industry relies heavily on 6V batteries, often of the GC2 size which is very common amongst cruisers.

Nearly everywhere on the planet these robust batteries are widely available. The reason many cruisers use 6V batteries is for increased cycle life, $$ per discharge, and $$ per Ah of capacity. The plates are thicker, taller and more robustly built than a 12V deep cycle of the same capacity. Their foot-print is also often smaller for a given Ah capacity.

The 6V battery will have only 3 cells where the 12 will need 6 cells thus thinner plates in the 12V battery. 6V wet cells win on price, Ah per dollar, and value every time. They do lack high acceptance rates, which with many charging systems on sailboats is a non-issue because they can't actually benefit from this due to HP and belt restrictions, they lack ability to lay them on their sides, and they do require maintenance and can "gas".

A bank of four 6V batts at 450 Ah's can accept charge current of about 20-25% of the 20 hour Ah rating. a 450 Ah wet bank can take the full output of a 100 AMP alt when deeply discharged but this won't last for very long as they charge begins to taper due to acceptance once at or near 80% of capacity or so. If you want to go bigger than 100 amp you will spend a lot of money on custom pulleys and brackets to fit a larger alt. In contrast that same bank in AGM could theoretically take well over 300 amps IF you had a way to feed it that, which most don't.

Testing has been done between 6V and 12V longevity but it does not take a scientist to see why a typical 12V battery with plates that are roughly .040-.060 thick can't compete longevity & cycle life wise with the typical 6V battery that has plates in the .105 -.110 thick range.

Here are typical plate thicknesses from four of the leading US 6V battery makers:

US Battery US2200 - 232 Ah, +Plate Thickness .110

Crown CR225 - 225 Ah, +Plate Thickness .105

Superior GC1200 - 220 Ah, +Plate .115

Trojan T105 - .110 (Trojan will not disclose this data but US Battery has done destructive testing on the Trojan's and confirmed the plate thickness)

My current favorite battery from the list above is the US Battery US2200 if you have a distributor near by, we don't have one in Maine so going to MA to get them is a pain, cron or Superior are great substitutes. US Battery competes directly with Trojan and the US2200 is their "T105 killer" yet costs significantly less.


Before asking, "is 500-600 amps enough", actually Ah's not amps, you should ideally know what the baseline of consumption is before you can know what "enough" needs to be. I would always suggest a battery monitor so you know accurately what your system is using in terms of consumption and what your charging sources are actually returning to the bank over how long a duration.

The Victron BMV-601 from Jamestown distributors is only $175.10 and a very good value but the Xantrex Link Lite is another great battery monitor though slightly more expensive. Buying this first, before major bank upgrades, can actually pay for other upgrades because you may find your calculations were way off and that 600 Ah bank you thought you needed, would really be more like 675 Ah's if using 6 6V batts, really only needed to be a 450 Ah bank, thus paying for the battery monitor. Every boater I have installed a battery monitor for raves about them and can't believe they did not do it sooner.

In short, a bigger bank is better. The bigger the bank the shallower the discharges will be. Deep discharges kill banks faster. If you have a bank you regularly cycle to 50% SOC (state of charge) vs. one you cycle to only 75% SOC then the bigger bank only dropping to 75% SOC will outlast the one regularly being discharged to 50%. 50% is the lowest you generally want to discharge to.

In my opinion 6V wet cells would be your best bang for the buck, should last a good long time if properly cared for, and you don't need a fancy regulator to run them unless the bank size at a 25% acceptance dwarfs your alternators output in which case alternator temperature sensing and an external regulator is a good idea.

Also, remember that when charging off an alternator you will rarely charge the bank back beyond 80%-85% of capacity due to time constraints and basic battery acceptance curves so this is where your solar and wind can help in a big way.
__________________
______
-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.


Reply With Quote Quick reply to this message Share with Facebook
  #5  
Old 10-25-2010
sailingdog's Avatar
Telstar 28
 
Join Date: Mar 2006
Location: New England
Posts: 43,290
Thanks: 0
Thanked 11 Times in 11 Posts
Rep Power: 13
sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice sailingdog is just really nice
I'd second getting the battery monitor before making any drastic changes. You really need to know what your baseline usage is before you can do any intelligent battery bank planning or sizing.
__________________
Sailingdog

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

Telstar 28
New England

You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.

—Cpt. Mal Reynolds, Serenity (edited)

If you're new to the Sailnet Forums... please read this
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
.

Still—DON'T READ THAT POST AGAIN.
Reply With Quote Quick reply to this message Share with Facebook
  #6  
Old 10-25-2010
chef2sail's Avatar
Senior Member
 
Join Date: Nov 2007
Location: Maryland
Posts: 7,052
Thanks: 30
Thanked 57 Times in 53 Posts
Rep Power: 8
chef2sail will become famous soon enough
Send a message via AIM to chef2sail
I agree with all Maine has said. The "footprint" is a big consideration as two 6 volt AMG lifelines take up the same room as 1 group 31with double the Ah.

I know I will get grilled for saying this, but I prefer the AGM as they can be laid on their side, accept the charge more quickly, and require no maintainence. To me it is worth the expense, but to many it is not worth double the price to most.

Before starting forward find out your daily electrical diet as MS said. Irt may save you in the end run.

Dave
__________________

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 Quick reply to this message Share with Facebook
  #7  
Old 10-25-2010
Junior Member
 
Join Date: Aug 2010
Posts: 23
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
kevandraper is on a distinguished road
Thanks

Thanks everyone, especially maine for the good advice and for taking the time to explain in detail. My understanding of batteries has now increased by a factor of 10 !!!! Buying a good battery monitor first makes sense.

My main concern was "draw" during the night, as a single hander I normally have the radar on, plus the autopilot, nav lights, VHF and HF. In fact the radar is more or less permanently on when I am sailing. I added a fairly loud external alarm to warn me of anything entering the set protection zone. I sometimes get carried away with repairs ( mainly the damn Perkins !)
Cheers
Reply With Quote Quick reply to this message Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now

In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




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
changing cutlass hillerpd Gear & Maintenance 4 09-26-2009 10:36 PM
Which oil changing pump is best? LJD Gear & Maintenance 24 08-11-2009 09:35 AM
Changing Halyard Gulfislander Gear & Maintenance 7 05-14-2007 12:22 AM
Changing Sheaves Booher Gear & Maintenance 3 01-12-2004 01:38 PM
Changing Engine Oil Tom Wood Gear and Maintenance Articles 0 10-02-2002 09:00 PM


All times are GMT -4. The time now is 10:01 PM.

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

The SailNet.com store is owned and operated by a company independent of the SailNet.com forum. You are now leaving the SailNet forum. Click OK to continue or Cancel to return to the SailNet forum.