Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 07-12-2014, 17:43   #1
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2014
Location: Astoria, NY
Boat: Sabre 38
Posts: 496
Different size batteries in new bank?

My new house bank is going to be 6 105s (each 6 volt, 225 amp hours). Realized that I have the space for two L16Hs (each 6 volts, 435 amp hours), which could replace 4 of the 105s.

There any problems with running the house bank with 2 105s and 2 L16Hs? Space wise it would be more efficient for pretty much the same capacity, but obviously would not do it if it creates problems.


Sent from my iPhone using Cruisers Sailing Forum
__________________

__________________
Stephen

s/v Carpe Ventum
1983 Sabre 38
My Intro
fallingeggs is offline   Reply With Quote
Old 07-12-2014, 17:54   #2
cruiser

Join Date: Feb 2008
Location: North Charleston, SC
Boat: Camano Troll
Posts: 4,669
Re: Different size batteries in new bank?

Most experts recommend that all batteries in a bank be the same brand, model and age. This is so they share the load and charging current evenly.

They don't have to be the same but they will work better if they are.
__________________

__________________
rwidman is offline   Reply With Quote
Old 07-12-2014, 20:06   #3
Registered User

Join Date: Sep 2013
Location: Beaufort, NC
Posts: 364
Re: Different size batteries in new bank?

Quote:
Originally Posted by fallingeggs View Post
My new house bank is going to be 6 105s (each 6 volt, 225 amp hours). Realized that I have the space for two L16Hs (each 6 volts, 435 amp hours), which could replace 4 of the 105s.

There any problems with running the house bank with 2 105s and 2 L16Hs? Space wise it would be more efficient for pretty much the same capacity, but obviously would not do it if it creates problems.


Sent from my iPhone using Cruisers Sailing Forum
Why not use 4 - L16H units and end up with 870 amp hrs vs 675 amp hrs for 6 - 6 105s?

Or 6 Fullriver 902-J350 and end up with 1005 amp hrs. Almost the same footprint as the 6 105s .

But 4 of the L16's would be the sweet way to do it if you have the height.
I would not build a bank with 2 different ratings, just asking for trouble.
__________________
Capt Hugh Wilde is offline   Reply With Quote
Old 07-12-2014, 21:46   #4
Registered User
 
Terra Nova's Avatar

Join Date: Apr 2007
Location: Marina del Rey, California
Boat: Freya 39 cutter- Terra Nova
Posts: 3,645
Re: Different size batteries in new bank?

Never mix battery sizes, brands, types or ages in the same bank.

Four L16's make up TN's house bank.
__________________
1st rule of yachting: When a collision is unavoidable, aim for something cheap.
"whatever spare parts you bring, you'll never need"--goboatingnow
"Id rather drown than have computers take over my life."--d design
Terra Nova is offline   Reply With Quote
Old 08-12-2014, 06:40   #5
Senior Cruiser

Cruisers Forum Supporter

Join Date: Aug 2014
Location: Astoria, NY
Boat: Sabre 38
Posts: 496
Re: Different size batteries in new bank?

Thanks all. Knew about type and age for sure. Now that I am thinking more about it, I can see several issues with charging and reading the state of charge with a bank with batteries that different in size.

Would like to put 4 L16s, but I don't think I have the room. Will have to take better measurements.


Sent from my iPhone using Cruisers Sailing Forum
__________________
Stephen

s/v Carpe Ventum
1983 Sabre 38
My Intro
fallingeggs is offline   Reply With Quote
Old 08-12-2014, 07:52   #6
Marine Service Provider

Join Date: Dec 2003
Location: South Carolina
Boat: Philip Rhodes Custom
Posts: 395
Re: Different size batteries in new bank?

Quote:
Originally Posted by rwidman View Post
Most experts recommend that all batteries in a bank be the same brand, model and age. This is so they share the load and charging current evenly.

They don't have to be the same but they will work better if they are.
There is no benefit to be gained by "sharing the load and charging current evenly" and in fact since every battery is different it never happens. Each battery will supply or receive current in proportion to its capacity so stronger batteries do their share and weaker batteries are not overloaded. There is no practical or theoretical justification for thinking they will work better if matched.

The misconception comes from two sources, the first is that batteries should be matched as closely as possible when in SERIES (as a chain is as strong as its weakest line) but it does not apply to PARALLEL. The second source is the common assumption that the current will split evenly between the batteries in parallel which has no basis.
__________________
Andina Marie is offline   Reply With Quote
Old 08-12-2014, 08:06   #7
cruiser

Join Date: Feb 2008
Location: North Charleston, SC
Boat: Camano Troll
Posts: 4,669
Re: Different size batteries in new bank?

Well as we can see not all experts agree.

Now lets talk about how to connect them together.
__________________
rwidman is offline   Reply With Quote
Old 08-12-2014, 10:01   #8
Marine Service Provider

Join Date: Dec 2003
Location: South Carolina
Boat: Philip Rhodes Custom
Posts: 395
Re: Different size batteries in new bank?

Oooo don't get me started there, symmetrical wiring is male bovine excrement.

The differential voltages that are going to be eliminated by symmetrical wiring are less than 10% of the normal manufacturing differences between batteries over which you have no control. You are putting lipstick on a Walrus .

Any inequality introduced during heavy loads gets equalized by battery to battery current within seconds of removing the load. Differential voltages during charging are typically less than 10 millivolts and as the current tapers to zero at full charge those disappear too.

Pick the shortest route with a minimum of connections.
__________________
Andina Marie is offline   Reply With Quote
Old 08-12-2014, 10:08   #9
cruiser

Join Date: Feb 2008
Location: North Charleston, SC
Boat: Camano Troll
Posts: 4,669
Re: Different size batteries in new bank?

Quote:
Originally Posted by Andina Marie View Post
Oooo don't get me started there, symmetrical wiring is male bovine excrement.

The differential voltages that are going to be eliminated by symmetrical wiring are less than 10% of the normal manufacturing differences between batteries over which you have no control. You are putting lipstick on a Walrus .

Any inequality introduced during heavy loads gets equalized by battery to battery current within seconds of removing the load. Differential voltages during charging are typically less than 10 millivolts and as the current tapers to zero at full charge those disappear too.

Pick the shortest route with a minimum of connections.
OK I'm with you on this one but a lot of folks would argue and post diagrams of various ways of wiring multiple batteries.
__________________
rwidman is offline   Reply With Quote
Old 08-12-2014, 10:26   #10
Registered User

Join Date: Nov 2014
Location: Falmouth, UK
Posts: 169
Re: Different size batteries in new bank?

"The second source is the common assumption that the current will split evenly between the batteries in parallel which has no basis"

So, if a 100ah battery was in parallel with a 200ah battery, for example, the current draw would be roughly in the ration of 1:2 between them? And I do emphasize roughly.
__________________
wiekeith is offline   Reply With Quote
Old 08-12-2014, 11:19   #11
Registered User

Join Date: Sep 2014
Location: North Wales
Boat: Saare 41cc
Posts: 33
Re: Different size batteries in new bank?

Quote:
Originally Posted by Andina Marie View Post
Oooo don't get me started there, symmetrical wiring is male bovine excrement.

The differential voltages that are going to be eliminated by symmetrical wiring are less than 10% of the normal manufacturing differences between batteries over which you have no control. You are putting lipstick on a Walrus .

Any inequality introduced during heavy loads gets equalized by battery to battery current within seconds of removing the load. Differential voltages during charging are typically less than 10 millivolts and as the current tapers to zero at full charge those disappear too.

Pick the shortest route with a minimum of connections.
I am with you on both points.
__________________
Derek Lumb is offline   Reply With Quote
Old 08-12-2014, 11:56   #12
Registered User
 
TeddyDiver's Avatar

Join Date: Aug 2010
Location: Arctic Ocean
Boat: Under construction 35' ketch
Posts: 1,826
Images: 2
Re: Different size batteries in new bank?

Remember you got to load up your batteries once a while and that doesn't work with mixed banks so well..
__________________

__________________
TeddyDiver is offline   Reply With Quote
Reply

Tags
size

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not 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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
can I mix different rudder angle indicator and different autopilots awab Marine Electronics 11 24-04-2013 15:25
new batteries with different voltage levels Han Electrical: Batteries, Generators & Solar 3 04-01-2009 16:07



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 00:36.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.