House battery capacity - 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 > On Board > Gear & Maintenance
 Not a Member? 
  #1  
Old 02-10-2001
wwilson's Avatar
Chesapeake Sailor
 
Join Date: Jul 2000
Location: Herrington Harbor, MD
Posts: 579
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 15
wwilson is on a distinguished road
House battery capacity

I''ve seen factors of 3 to 4 X used for the calculation of house battery bank capacity to daily electrical load. Ignoring, for the moment, other complicating factors such as on-board generating devices, # sustained days at load, etc., is anyone fimiliar with a rule of thumb for a first order estimate of AHr storage capacity to daily use?
Reply With Quote Quick reply to this message Share with Facebook
  #2  
Old 02-10-2001
Senior Member
 
Join Date: Feb 2001
Posts: 112
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 14
walt123 is on a distinguished road
House battery capacity

total amps used x hours x % natural battery [includes system leakage] loss per day and figure in a temperature factor and type of batter used, wet or gel
Reply With Quote Quick reply to this message Share with Facebook
  #3  
Old 02-11-2001
Junior Member
 
Join Date: Jan 2001
Posts: 23
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
dazeoff is on a distinguished road
House battery capacity

Have a look at Nigel Calders book on boat electrics. I have 2 x 200A/hr gels, and a seperate starting battery. Whatever you do it never seems to be enough, NOW I have a wind gen. and solar and still use the engine 3/4 of an hour each day. The fridge is the killer - but I have to keep the beer cool.
Reply With Quote Quick reply to this message Share with Facebook
  #4  
Old 02-13-2001
wwilson's Avatar
Chesapeake Sailor
 
Join Date: Jul 2000
Location: Herrington Harbor, MD
Posts: 579
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 15
wwilson is on a distinguished road
House battery capacity

thanks dazeoff-

I found the source of the recommended batery sizing factor. West Marine Advisor recommends a storage capacity of 3 to 4 times the average daily use in AH. I''ll get Calder''s book and see what he has to say as well before spending any money on batteries!

wayne
Reply With Quote Quick reply to this message Share with Facebook
  #5  
Old 02-15-2001
Member
 
Join Date: Jan 2001
Posts: 33
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
munchimike is on a distinguished road
House battery capacity

You gentlemen are being a little too cerebral about this; and eventually the factor that none of you have mentioned will catch up with you......attrition. The life of your batteries will decrease at an ever increasing rate, the charge capability will diminish, and who knows how much resistance increases in all of your wiring as the copper takes a load for a few years?? Don''t do it, don''t even try; there will never be a perfect formula. Get 6-volt batteries and up your amp hour capability. Get a bunchofem. Mark each one for startup date. Measure the charge every year,....replace as necessary. Get more than you''ll need, keep experimenting,..stop calculating. Rev....maritimetradition.com
Reply With Quote Quick reply to this message Share with Facebook
  #6  
Old 02-18-2001
Junior Member
 
Join Date: Jun 2000
Posts: 2
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 0
peerlessg is on a distinguished road
House battery capacity

Nigel Calder estimates that, including what he calls fudge factors, you need battery capacity equivalent to 4 times your daily usage, i.e., if you need 100 amps per day then according to Nigel you need 400 amp hours. He gives a detailed rationale for all of this. Notwithstanding his considerable expertise and experience, I think he is being quite conservative in his assessment and I personally be comfortable with 3 times daily usage requirements.
Reply With Quote Quick reply to this message Share with Facebook
  #7  
Old 02-18-2001
Senior Member
 
Join Date: Oct 2000
Posts: 629
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 15
kimberlite is on a distinguished road
House battery capacity

since your batteries are dead at about 50%
3 times your daily use only gives you a day and a half before dead batts.
eric
Reply With Quote Quick reply to this message Share with Facebook
  #8  
Old 03-07-2001
Member
 
Join Date: Dec 2000
Posts: 60
Thanks: 0
Thanked 0 Times in 0 Posts
Rep Power: 15
Constantin is on a distinguished road
House battery capacity

There are a number of factors that influence the size of the battery bank. The usual consensus is a battery capacity around 3-4x of daily needs (although Surrette has a guide based on boat length). Calder advocates 4x daily need, or 4x max temporary load, whichever is greater. AGMs or Gel-cells may allow higher temp loads, so the maximum temporary load factor can be reduced to 3x with them.

A battery is considered "dead" when it only retains 80% of its rated charge. Thus, unless you use cheap Trojans or other bargain batteries, it''ll be a while before you wear down the battery to this point. To go to one extreme: the Surrette/Rolls CS series can sustain 3,200 cycles at 50% Depth of Discharge before it''s "dead". That''s 9+ years of daily use, assuming one discharge to 50% per day. The AGM batteries I use are rated for 1,000 such cycles...

Ideally you won''t discharge the house bank deeper than 50% on a daily basis, cycling it between 80% and 55% (if you used the 4x rule) since this allows bulk charging (much higher replenishment rates than at higher states of charge) which minimizes engine runtime, fuel consumption, and wear. A 4x battery bank also gives you three days of charge if the generator/alternator fails.

Have one starter bank and one house bank. Keep the two circuits completely separate except during charging. The two banks should have similar battery types in them (Gel, AGM, Flooded) although using an isolator/eliminator by Ample Power gets around this.

Have a look at my battery page for more info: http://www.vonwentzel.net
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
Battery Charger / Maintainer Tree Gear & Maintenance 6 10-26-2004 11:53 PM
Battery loses charge svzephyr44 Gear & Maintenance 1 09-28-2004 03:20 PM
Starter or House Battery? rrobar Gear & Maintenance 2 12-30-2003 04:56 PM
Battery Switch johar Gear & Maintenance 4 04-08-2003 05:28 PM
Dual Battery Installation Urband Gear & Maintenance 1 03-25-2002 09:57 PM


All times are GMT -4. The time now is 12:09 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

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.