Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 19-05-2024, 09:01   #1
Registered User

Join Date: Sep 2020
Location: South Aegean, Greece
Boat: Oyster 39
Posts: 17
Please help - One side of battery parallel not drawing current...

Hi,

I'm having an unexpected issue with my battery connections. I have 4 x 115Ah 12v house batteries. Two from each are in series to create 2 x 115Ah 24v batteries.

When I check the current draw only one set of the 24v batteries in parallel seem to be providing current.

I expected current to draw from both at equal rates. Is what I'm seeing normal or is it likely one of my batteries is faulty?

I have attached a drawing to show the wiring. I've included an original set up and then a later more standard set up.

Originally I had each 24v battery wired to a joining terminal then to a switch. With the idea of having all wiring connections equal. I then reverted to the normal positive to positive set up.

A troubleshooting step would be to switch the batteries around on the connections and if the results reverse it's likely a battery issue but I'm still not sure that would be definitive.

Also, I assume it is more likely to be one faulty battery rather than both 12v units. And I feel it's unlikely to be the wiring because I've used all correctly size and installed components and done that twice with the same results.

Would appreciate if someone could help.
Attached Thumbnails
Click image for larger version

Name:	NOTE20240519162546.jpg
Views:	136
Size:	169.9 KB
ID:	290062  
DoctorCaptain is offline   Reply With Quote
Old 19-05-2024, 10:11   #2
Registered User

Join Date: May 2016
Location: Bradenton, FL https://share.garmin.com/seaseeker
Boat: Manta 42 Mk IV Catamaran
Posts: 156
Re: Please help - One side of battery parallel not drawing current...

What is the battery chemistry? If LiFPo4 it could be a different state of charge. Did you balance the batteries first?
Avionics_Joe is offline   Reply With Quote
Old 19-05-2024, 10:26   #3
Registered User

Join Date: Mar 2016
Location: San Francisco
Boat: Morgan 382
Posts: 3,057
Re: Please help - One side of battery parallel not drawing current...

Do like the lower drawing, except take the positive from the top battery. Such that positive comes from one battery, and negative from the other.

When you connect them, both batteries should be at the same state of charge, which most easily is full. Make sure all the connections are clean. Don't assume they are, use a wire brush or sandpaper on them. If the batteries are different ages, different states of charge, or some are otherwise in a lessor condition, then the current draw will not be equal. Nothing you can really do to change that.

How different is the current draw, and how are you measuring it? How do all the batteries test when checked one at a time out of the circuit? What type of batteries are these?
__________________
-Warren
wholybee is offline   Reply With Quote
Old 19-05-2024, 10:50   #4
Registered User

Join Date: Sep 2020
Location: South Aegean, Greece
Boat: Oyster 39
Posts: 17
Re: Please help - One side of battery parallel not drawing current...

Batteries are sealed lead acid.
They are now set up as per the lower drawing.
All 4 are bought new together 24 months ago.
All connections are good, brand new wires, connectors etc everywhere.
Batteries all had 12v nominal voltage when tested individually. I.e. they all had the same voltage.
The current draw is all from one side and zero from the other side.
I'm using a clamp on multi meter to test the current.

Another idea would be to test each 24v set individually to see if one is faulty.

I'm guessing from the responses so far what I'm seeing isn't normal and I'll need to troubleshoot further...
DoctorCaptain is offline   Reply With Quote
Old 19-05-2024, 11:19   #5
Registered User

Join Date: May 2024
Posts: 4
Re: Please help - One side of battery parallel not drawing current...

Hi,

Water always chose the shortest way from A to B ..... And so do electrical current. Also the batteries should have the same lot numbers, and have been used in the same battery Bank making them almost identical.
On your drawing the Lower two batteries have shorter connections ( less resistance than the Upper two batteries ) hence the Water example..
Make two identical positive cable connections, same diameter and length, between the + poles and the switch as well as to identical negative cables to the - side of the batteries ( same cable diameter and length ) and the current will see the same resistance, from each group of batteries to the switch and share the delivered current.
Sailer4life is offline   Reply With Quote
Old 19-05-2024, 12:17   #6
Registered User

Join Date: Sep 2020
Location: South Aegean, Greece
Boat: Oyster 39
Posts: 17
Re: Please help - One side of battery parallel not drawing current...

Quote:
Originally Posted by Sailer4life View Post
Hi,

Water always chose the shortest way from A to B ..... And so do electrical current. Also the batteries should have the same lot numbers, and have been used in the same battery Bank making them almost identical.
On your drawing the Lower two batteries have shorter connections ( less resistance than the Upper two batteries ) hence the Water example..
Make two identical positive cable connections, same diameter and length, between the + poles and the switch as well as to identical negative cables to the - side of the batteries ( same cable diameter and length ) and the current will see the same resistance, from each group of batteries to the switch and share the delivered current.
All batteries are exactly the same bought and used at the the same time.

They were originally set up as per the first drawing with the same wire lengths.

I had the same problem then.
DoctorCaptain is offline   Reply With Quote
Old 19-05-2024, 12:59   #7
always in motion is the future
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 19,177
Re: Please help - One side of battery parallel not drawing current...

You need to be able to isolate the batteries. Use an OFF-A-B-BOTH switch.
__________________
“It’s a trap!” - Admiral Ackbar.

s/v Jedi is offline   Reply With Quote
Old 19-05-2024, 21:04   #8
Registered User

Join Date: Sep 2020
Location: South Aegean, Greece
Boat: Oyster 39
Posts: 17
Re: Please help - One side of battery parallel not drawing current...

Quote:
Originally Posted by s/v Jedi View Post
You need to be able to isolate the batteries. Use an OFF-A-B-BOTH switch.
Will that not start to get messy if I have 3 - 4 batteries?

I take your point though, now I'm going to have to manually isolate each battery to fault check.
DoctorCaptain is offline   Reply With Quote
Old 19-05-2024, 21:23   #9
Registered User

Join Date: Apr 2018
Location: Med
Boat: X442
Posts: 710
Re: Please help - One side of battery parallel not drawing current...

It's not a big intervention to simply disconnect the working side and see what happens.
HeinSdL is offline   Reply With Quote
Old 19-05-2024, 22:09   #10
always in motion is the future
 
s/v Jedi's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: in paradise
Boat: Sundeer 64
Posts: 19,177
Re: Please help - One side of battery parallel not drawing current...

Quote:
Originally Posted by DoctorCaptain View Post
Will that not start to get messy if I have 3 - 4 batteries?

I take your point though, now I'm going to have to manually isolate each battery to fault check.
If you plan more than 2 batteries, use simple on/off switches for each battery that connect to a shared busbar. I use that even though I only have two batteries for redundancy reasons (switches can go bad too).

Imagine a situation where a faulty battery is drawing down other parallel batteries without blowing a fuse. You want to be able to quickly isolate batteries.
__________________
“It’s a trap!” - Admiral Ackbar.

s/v Jedi is offline   Reply With Quote
Old 20-05-2024, 07:14   #11
Registered User
 
deblen's Avatar

Join Date: Oct 2014
Location: Bay of Fundy,Grand Manan,N.B.,Canada N44.40 W66.50
Boat: Mascot 28 pilothouse motorsailer 28ft
Posts: 3,412
Images: 1
Re: Please help - One side of battery parallel not drawing current...

https://marinehowto.com/category/electrical/
__________________
My personal experience & humble opinions-feel free to ignore both
.
deblen is offline   Reply With Quote
Old 21-05-2024, 06:43   #12
Registered User

Join Date: Sep 2020
Location: South Aegean, Greece
Boat: Oyster 39
Posts: 17
Re: Please help - One side of battery parallel not drawing current...

Quote:
Originally Posted by s/v Jedi View Post
If you plan more than 2 batteries, use simple on/off switches for each battery that connect to a shared busbar. I use that even though I only have two batteries for redundancy reasons (switches can go bad too).

Imagine a situation where a faulty battery is drawing down other parallel batteries without blowing a fuse. You want to be able to quickly isolate batteries.
That's a fair point and I like the simplicity. Thanks 👍
DoctorCaptain is offline   Reply With Quote
Old 21-05-2024, 07:14   #13
Registered User

Join Date: Jan 2023
Location: British Columbia
Boat: Hunter 380
Posts: 62
Re: Please help - One side of battery parallel not drawing current...

Have you checked the electrolyte level? Specific gravity? When were they last equalized? If you disconnect everything, what are the individual battery voltages?

I'd take the neg off one bank,then the pos off another bank. Is there a fuse before the bus bar?
cram is offline   Reply With Quote
Old 21-05-2024, 07:43   #14
Registered User

Join Date: Apr 2022
Posts: 248
Re: Please help - One side of battery parallel not drawing current...

Yup, loads from positive of "pair #1". Negative from negative of "pair #2"


And, a little concerned that an odd number of batteries was mentioned. Batteries need to be installed ONLY in pairs of 12 VDC to give you 24 VDC.
Wolfe10 is offline   Reply With Quote
Old 21-05-2024, 11:38   #15
Registered User

Join Date: Mar 2007
Location: Santa Cruz
Boat: SAnta Cruz 27
Posts: 6,838
Re: Please help - One side of battery parallel not drawing current...

Simply measure the voltage across each 12v battery. One set should measure about the same voltage, the set without output should measure quite differently.
donradcliffe is offline   Reply With Quote
Reply

Tags
battery, current, lease

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Village Marine Watermaker "Little Wonder" Drawing High Current OSBNZ Plumbing Systems and Fixtures 3 17-06-2023 11:52
Battery charger drawing current when off crayiii Electrical: Batteries, Generators & Solar 0 05-03-2023 12:26
winch battery on house side or starting side shadowdancer Electrical: Batteries, Generators & Solar 0 03-05-2019 06:09
Drawing from battery while at dock dmksails Electrical: Batteries, Generators & Solar 15 07-05-2018 06:51
Four Solar Panels - Parallel , Series or Series-Parallel west coaster Electrical: Batteries, Generators & Solar 76 07-07-2011 14:35

Advertise Here


All times are GMT -7. The time now is 19:04.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.