Mixing 6-volt and 12-volt Batteries? - SailNet Community
LinkBack Thread Tools
post #1 of 4 Old 11-08-2008 Thread Starter
Junior Member
Join Date: Sep 2008
Posts: 7
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
Mixing 6-volt and 12-volt Batteries?

I need to replace my two 12-volt batteries. They are setup as two independent banks with a standard 1-2-both master switch. I would like to replace these with the more durable and higher amp/hr rated six volt batteries. My problem is I don't have enough space for four 6-volts. I can fit two 6-volts (225 amps) into the space now occupied by the two 12-volts (bank one). I then have only enough room for one 12-volt (130 amps) in another locker (bank two). Any ideas about mixing battery banks with different amp ratings?
captainfrank is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
post #2 of 4 Old 11-08-2008
midlife crisis member
AllThumbs's Avatar
Join Date: Jul 2008
Posts: 975
Thanks: 0
Thanked 12 Times in 10 Posts
Rep Power: 9
If the two 12 volt batteries you are replacing are 130 A each then replacing them with two 6 volt 225 A batteries will give you less capacity than you had before. The 6 volters would need to be connected in series for 12 volts @ 225 A, while the 12 volters were connected in parallel for 12 volts @ 260 A

Plus those ratings seem like peak current ratings which don't mean that much. You need to see what the battery capacities are in Amp-hours. Perhaps the ratings you listed there are indeed amp hours.

To answer your question, using batteries of differing capacities in parallel is ok but not ideal. Charging them could be a problem depending on weather they are charged seperately of as one big pack, and also how quickly they are charged.


I sail.
AllThumbs is offline  
Quote Quick Reply Share with Facebook
post #3 of 4 Old 11-08-2008
Telstar 28
sailingdog's Avatar
Join Date: Mar 2006
Location: New England
Posts: 43,290
Thanks: 0
Thanked 18 Times in 14 Posts
Rep Power: 16
The other problem with having a 12 VDC battery bank of just two SIX Volt batteries is that if either goes dead, you lose the entire bank... That is why I highly recommend any battery bank made up of SIX volt batteries be four-batteries minimum.


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.

sailingdog is offline  
Quote Quick Reply Share with Facebook
post #4 of 4 Old 11-08-2008
camaraderie's Avatar
Join Date: May 2002
Location: East Coast
Posts: 13,877
Thanks: 0
Thanked 6 Times in 6 Posts
Rep Power: 18
T105 6V batteries ARE generally rated around 225@hours at the 20 hour rate, thus two of them will rate 225@hours @ 12V. This will be a reduction in your amphours, but if the construction is better than the 12V your were using, it may be worth the tradeoff.
I am not aware of any standard 12V battery size that rates 130amps at 20 hrs.. The group 31's typically rate 100-110 and the 4D's are generally over 150-160. What exactly do you have there?

In any event...there is NO problem mixing 12V batteries with 6V batteries paired as 12V's as long as the construction type is the SAME...i.e. flooded or AGM or GEL.

I think Dawgs concern is misplaced...as even if you lose the 2 6V batteries...you will still have a working 12V battery. If the pair of 6V's were your only source then I would agree.

No longer posting. Reach me by PM!
camaraderie is offline  
Quote Quick Reply Share with Facebook

Quick Reply

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:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


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
Show Printable Version Show Printable Version
Email this Page Email this Page

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome