RV News RVBusiness 2021 Top 10 RVs of the Year, plus 56 additional debuts and must-see units → ×
 


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 08-10-2019, 01:50 PM   #1
2 Rivet Member
 
2016 25' International
Wanamingo , Minnesota
Join Date: Nov 2009
Posts: 28
Images: 1
Best way to hook up auxiliary batteries.

I acquired two AGM group 27 12v batteries. I'd like to use them as auxiliary/back-ups & keep them in my pickup bed. My plan was to wire them to a plug that matches the the female plug on my tow vehicle to plug the camper into when I wanted to use these batteries. Is this a reasonable way to do this, or should I wire it to my Airstream another way?
Scout1 is offline   Reply With Quote
Old 08-10-2019, 01:58 PM   #2
Rivet Master
 
Mollysdad's Avatar

 
2017 26' Flying Cloud
Tampa , Florida
Join Date: Feb 2017
Posts: 5,343
Blog Entries: 1
Did you plan to wire them in parallel to the regular batteries?
Mollysdad is online now   Reply With Quote
Old 08-10-2019, 03:26 PM   #3
PKI
Rivet Master
 
PKI's Avatar
 
Currently Looking...
Walnut Creek , California
Join Date: May 2015
Posts: 3,907
Do not forget to include monitoring/switching/fusing/circuit protection in your cabling as well as a method to secure the aux battery box. Pat
PKI is offline   Reply With Quote
Old 08-11-2019, 11:43 AM   #4
2 Rivet Member
 
2016 25' International
Wanamingo , Minnesota
Join Date: Nov 2009
Posts: 28
Images: 1
Thanks for the feedback, but maybe my question was unclear. What I'm wondering is will hooking up my auxiliary battery as shown in the attached picture be satisfactory, or is there a more efficient (electronically) way of doing it. Such as wiring it parallel with my house batteries. I'd like to do it the way I have pictured, just for simplicity's' sake. It is wired so it powers the trailer just like the tow vehicle would it was plugged into it.
Attached Thumbnails
Click image for larger version

Name:	20190811_112224.jpg
Views:	29
Size:	530.7 KB
ID:	349104  
Scout1 is offline   Reply With Quote
Old 08-11-2019, 12:57 PM   #5
CLOUDSPLITTER "Tahawus"
 
ROBERT CROSS's Avatar

 
2003 25' Classic
Zanadude Nebula , Milky Way
Join Date: Jun 2007
Posts: 16,773
Images: 1
That is doable, but not as efficient as 4awg wired directly to the coach batteries. You could use a high amp quick connect.

Bob
🇺🇸
__________________
ďItís not the system thats the problem, think Circus, itís not the car, itís that the car is full of Clowns.Ē
John Turley



Tahawus
🌤
ROBERT CROSS is online now   Reply With Quote
Old 08-12-2019, 08:30 AM   #6
2 Rivet Member
 
2016 25' International
Wanamingo , Minnesota
Join Date: Nov 2009
Posts: 28
Images: 1
Robert, I have two 6v lifeline AGM batteries in the trailer mated with 470 watts of solar on the trailer roof. The auxiliary batteries will actually be two 12v AGM batteries. Your saying with this set-up it would be best to attach this 12v bank (using the plugs you referenced) in parallel with the 6v bank? That makes sense to me, but just want to be sure. I have searched, but not been able to find any reference to this type of set-up. Thanks for the help?
Scout1 is offline   Reply With Quote
Old 08-12-2019, 10:16 AM   #7
Rivet Master
 
batman's Avatar
 
1964 22' Safari
modesto , California
Join Date: Jul 2010
Posts: 1,045
I agree 4 awg welding cable is much better than the 10 ga wire that is used in the trailer to TV umbilical.

4 awg welding cable and Anderson connectors like the SB-50 or SB-175 would work better. Anderson connectors are great connectors for battery applications, wenches ,etc.

http://www.amazon.com/EWCS-Approved-...g%2C220&sr=1-3
It is not necessary to go marine grade, I just like overkill.

https://www.andersonpower.com/shop/s...k-keyless.html
SB-50 (50 AMP) would probably work fine, However SB-175 IS (175 AMP).

Best of luck with your project.

-Dennis
batman is offline   Reply With Quote
Old 08-12-2019, 11:29 AM   #8
PKI
Rivet Master
 
PKI's Avatar
 
Currently Looking...
Walnut Creek , California
Join Date: May 2015
Posts: 3,907
Does this all depend upon the specific use profile?

For a few amps, no or rather minimal problems. For the situation where the trailer bank is low, those batteries will pull power - possibly more power than the fusing on the umbilical will support.

Then, there is the charging profile, the battery state monitoring, and the lack of regulation associated with the proposed method.

In an emergency and with managed control, maybe. However, as a standard approach to normal use, this seems like a simple solution at first glance that gets more complicated as you consider the possibilities.

Backup battery bank - suggest you add a disconnect for the primary and also add a high amp plug connector. Then unplug the main when at minimum capacity and plug in the secondary. The disconnect eliminates the load for safe connection and the separate banks eliminate battery state conflict. Using 6 and 12 volt batteries in a combined bank may work - 12 volt is 12 volt, but the interaction between cells is normally considered at a minimum poor practice.

Not an expert - suggest you spend some time consulting with one. I'll be interested to hear that information. Your question is an interesting one as the proposal is simple to implement. Just not convinced it is the right way to proceed. Maybe the solution is as simple as disconnecting the battery cables on the main bank while you use the backup. Pat
PKI is offline   Reply With Quote
Old 08-16-2019, 11:21 AM   #9
2 Rivet Member
 
2018 27' Globetrotter
Richardson , Texas
Join Date: Feb 2018
Posts: 20
Quote:
Originally Posted by Scout1 View Post
Thanks for the feedback, but maybe my question was unclear. What I'm wondering is will hooking up my auxiliary battery as shown in the attached picture be satisfactory, or is there a more efficient (electronically) way of doing it. Such as wiring it parallel with my house batteries. I'd like to do it the way I have pictured, just for simplicity's' sake. It is wired so it powers the trailer just like the tow vehicle would it was plugged into it.
Scout,

That set-up would only work if you are counting on a couple of amps (maybe up to 5A) of current coming out of the aux battery. What that set-up would do would be to put the batteries in paralllel, but through a rather high amount of wire resistance. That resistance imbalance will kill any help out of the AUX battery at high current. The same issue is present when charging from solar, most of the current would go into the trailer battery until it is charged and then (and only then) would the external battery get any charging current.

A high current example: two 12V batteries wired in parallel properly (all current paths are matched. At 100A they both see 50A.

Now add an inbalance of 625 microohms (30" of #4 wire): trailer battery then delivers 83A and the 2nd battery delivers 17A! It does not take much of an imbalance in the wiring to totally foul up the matching of parallel connections at high current.
DLDINS is offline   Reply With Quote
Old 09-10-2019, 11:18 AM   #10
2 Rivet Member
 
2016 25' International
Wanamingo , Minnesota
Join Date: Nov 2009
Posts: 28
Images: 1
Thanks for the help. I'll disconnect the house batteries before I plug in the auxiliary. Seems like the best option.
Scout1 is offline   Reply With Quote
Reply


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
Best way to "drive" the 7-way umbilical kittmaster Electrical - Systems, Generators, Batteries & Solar 7 05-14-2019 08:33 AM
My Hook Things Won't Hook Sbb Rock Guards, Segment & Window Protectors 2 04-12-2015 07:16 PM
Hook up OR Not Hook up while camping purman Boondocking 29 08-18-2009 07:42 PM
Charging Auxiliary Batteries COLORADO_CAMPER Batteries, Univolts, Converters & Inverters 9 06-09-2008 11:16 AM
Auxiliary batteries won't hold charge Lena Abbott Batteries, Univolts, Converters & Inverters 5 09-26-2006 07:36 PM


Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by the Airstream, Inc. or any of its affiliates. Airstream is a registered trademark of Airstream Inc. All rights reserved. Airstream trademark used under license to Social Knowledge LLC.



All times are GMT -6. The time now is 07:24 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, Jelsoft Enterprises Ltd.