Go Back   iRV2 Forums > TRAVEL TRAILER, 5th WHEEL & TRUCK CAMPER FORUMS > Travel Trailer Discussion
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 05-02-2014, 09:51 AM   #1
Member
 
smonagle's Avatar
 
Join Date: May 2013
Location: Clifton Springs, NY
Posts: 77
Parallel Battery Question

Hello all....I am going to add a second 12v battery to my TT. I understand how to connect the two together in parallel. However, I have seen a couple different options regarding the wires coming from the trailer. Some have both positive and negative on the same battery, others have the positive off of battery 1 and negative off of battery 2. Which one should I be doing? Thanks!
__________________

__________________
2011 Coleman 267BH Fifth Wheel - Traveling Camper
2011 Chaparral 330FBH Fifth Wheel - Seasonal Camper
2013 Ram 2500 5.7 Hemi - 3.73 Axle
smonagle is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 05-02-2014, 09:59 AM   #2
Senior Member
 
Join Date: Sep 2012
Posts: 4,232
Parallel is pos to pos, and neg to neg.



Series is neg to pos.

__________________

__________________
jesilvas is offline   Reply With Quote
Old 05-02-2014, 10:07 AM   #3
Senior Member
 
Skip426's Avatar


 
Join Date: Apr 2011
Location: Powell River, B.C.
Posts: 14,970
Some good info here.

The 12volt Side of Life (Part 1)
__________________
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
Skip426 is offline   Reply With Quote
Old 05-02-2014, 10:11 AM   #4
Member
 
Auto hauler's Avatar
 
Excel Owners Club
Join Date: May 2012
Posts: 99
Quote:
Originally Posted by smonagle View Post
Hello all....I am going to add a second 12v battery to my TT. I understand how to connect the two together in parallel. However, I have seen a couple different options regarding the wires coming from the trailer. Some have both positive and negative on the same battery, others have the positive off of battery 1 and negative off of battery 2. Which one should I be doing? Thanks!
Either way will work as long as you have solid heavy connections between the batteries.. Although in theory, it may better distribute the load doing the latter. Of all the stuff I have with dual or more batteries, I have some done both ways. Right or wrong, I've not seen any real difference either way.
__________________
Tom I.
2006 Excel 36BDO
2012 Dodge 3500
Auto hauler is offline   Reply With Quote
Old 05-02-2014, 11:23 AM   #5
Senior Member
 
Join Date: Jun 2013
Location: Gilbert, AZ
Posts: 237
It makes no difference. Usually, I will wire it whichever way is easier. Power wise, they are in parallel either way and you will get the same exact output.
__________________
Nunyadamn is offline   Reply With Quote
Old 05-02-2014, 11:36 AM   #6
Senior Member
 
J Birder's Avatar
 
Join Date: Feb 2012
Location: Lake County, IL
Posts: 1,193
Either way will work, but one works better. If they both go to the same battery, there will be greater current draw from that battery and it will also charge faster. It you connect the positive to one battery and the negative to the other, current flow will be much more even.

Joel
__________________
Retired electronics engineer. Avid paddler & birder.
2011 Silverado 2500HD, diesel, 4x4,crew cab, 8' bed
Palomino Puma 253FBS (27' 5er) & '94 19' Class B
J Birder is offline   Reply With Quote
Old 05-03-2014, 10:48 AM   #7
Senior Member
 
wa8yxm's Avatar
 
Damon Owners Club
Workhorse Chassis Owner
Join Date: Mar 2009
Posts: 22,787
Ah, the old "Balancing" issue.

IF you have a big inverter, something that can suck 100 or 100s of amps off the batteries then balancing may be an issue.

If you are just running lights, a radio, water pump and control systems. Use good quality Starter Cable to parallel the batteries, Try to get one red and one black for obvious reasons (red is positive) and do not worry about it.

With good heavy paralleling cables (Those wires can pass 100 amps no sweat) on a non-inverter RV (or small inverter RV) balancing is not that big a deal....

Even with a whomping big inverter sucking 200 amps or more.. I'm not sure it's that big a deal.. MOST of what I hear about balancing and/or mis-matched batteries.. Is a myth.
__________________
Home is where I park it!
wa8yxm is offline   Reply With Quote
Old 05-04-2014, 06:48 AM   #8
Senior Member
 
Join Date: May 2014
Posts: 568
One important thing to remember, when tying two batteries together you are only going to have the current available of the weakest battery. If bat 1 has more ampere hours than the other you will only pull the lower ah. Its like a funnel. Make sure the batteries match exactly. Simplest example I can post. Good luck
__________________
RVGuy1966 is offline   Reply With Quote
Old 05-04-2014, 07:43 AM   #9
Senior Member
 
94-Newmar's Avatar
 
Join Date: Nov 2009
Posts: 2,043
Quote:
Originally Posted by wa8yxm View Post
Ah, the old "Balancing" issue...........
Even with a whomping big inverter sucking 200 amps or more.. I'm not sure it's that big a deal.. MOST of what I hear about balancing and/or mis-matched batteries.. Is a myth.
Amen... well, except the mis-matched batteries thing. Having a couple dead cells in one battery group can cause issues with the others.

Typically, the only reason to grab a + or - from another battery is to spread out the number of stacked connectors on each terminal. I've seen many DIY projects on coaches where they've added additional terminal posts to one post and stacked 8 terminals on 1 battery post...

Scary stuff..
__________________
94-Newmar Kountry Star 40-KSDP
Spartan/Cummins 8.3C-300HP/Allison 3060 WTEC-II/25yr RV Tech RVIA Certified/Onan-Cummins Certified
94-Newmar is offline   Reply With Quote
Old 05-04-2014, 10:07 PM   #10
Senior Member
 
Franka548's Avatar
 
Freightliner Owners Club
Retired Fire Service RVer's
Join Date: Apr 2011
Location: N E Ohio
Posts: 3,448
It is better to take the positive from one battery to the coach, and the negative from the 2nd battery. Although both will work as others have said, you might as well do it the right way the first time, so you don't have issues later. As others have said, make sure your batteries are matched and are of the same size and amp ratings.
Frank
__________________
05 Alfa Gold 40' Motor Home "Goldie" 03 Malibu Toad towing 4 down
03 Silverado cclb 3500 drw, D/A, Reese 22k hitch
07 Alfa SeeYa Gold 30RL,2 slides,power everything Above for sale PM me for details
Franka548 is offline   Reply With Quote
Old 05-05-2014, 09:27 AM   #11
Senior Member
 
wa8yxm's Avatar
 
Damon Owners Club
Workhorse Chassis Owner
Join Date: Mar 2009
Posts: 22,787
Quote:
Originally Posted by 94-Newmar View Post
Amen... well, except the mis-matched batteries thing. Having a couple dead cells in one battery group can cause issues with the others.

Typically, the only reason to grab a + or - from another battery is to spread out the number of stacked connectors on each terminal. I've seen many DIY projects on coaches where they've added additional terminal posts to one post and stacked 8 terminals on 1 battery post...

Scary stuff..
I have had dead cell in one battery and good cells in the other.. This has happened both in the OEM Six volt which of course were matched (Though I consider the pair of six volt to be one single 12 volt) and in 12 volts I had in a different loop.

Fact is matched or not.. A dead cell in one will cause issues in the battery bank... It does not matter if batteries in parallel are matched.

batteries in series.. Those need to be matched, which is why this Motor home sports a brand new pair of DEKA 230 amp hour Golf car batteries.
__________________
Home is where I park it!
wa8yxm is offline   Reply With Quote
Old 09-21-2014, 08:51 PM   #12
Member
 
wwsmith111's Avatar
 
Join Date: Sep 2014
Posts: 59
Millions of big OTR trucks use three or four 12v batteries in parallel. After the first battery failure there will be an odd ball battery in the group, and then a second and a third. Bottom line is the batteries will work fine together regardless if they are different sizes and/or capacities as long as they are all good i.e. no bad cells, etc. My TT has room for one group 27 and one group 24 which is what I have. I haven't had any issues as long as the batteries are good. Bad battery = change it for a new one. Just keep the water level up in the batteries especially on the group 24 as it will have a tendency to boil the water out as the charger keeps charging to bring up the larger capacity group 27 battery to full charge. A group 27 + a group 24 in parallel will give you noticeably more capacity than two group 24s. I know, I've tried it both ways...
__________________

__________________
2011 5.7l Toyota Tundra w/ Roadmaster Suspension.
2014 Jayco Eagle 338 RLTS w/ 7hp gen & 1000w invert.
PowerTwin II-30" Electric RV Leveling Stabilizer.
wwsmith111 is offline   Reply With Quote
Reply

Tags
battery



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

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
Battery Charging Question atamians Travel Trailer Discussion 12 05-03-2014 10:16 PM
Chassis battery question becks Monaco Owner's Forum 20 03-20-2014 02:30 PM
Generator starting battery question Jasper7821 RV Systems & Appliances 26 01-30-2014 01:11 PM
Battery Question spinn Newmar Owner's Forum 10 01-24-2014 05:48 PM
Question about battery bank system and length of wire to purchase Jasper7821 RV Systems & Appliances 9 01-24-2014 03:48 PM

» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 08:19 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.