Reply
 
Thread Tools Display Modes
Old 08-31-2012, 03:43 PM   #1
Member
 
Join Date: May 2012
Posts: 93
Two 12V Batteries?

I want to mount two 12V batteries on the hitch of my 186SPT. Question: Using parallel wiring, will my truck alternator charge both batteries while I drive without any additional modifications or parts? And I assume that if the answer is "yes", then when I'm hooked up to shore, that both batteries would be charged as well Now it does a fine job of charging one. Thanks!
__________________

rmdrifter is offline   Reply With Quote
Old 08-31-2012, 03:49 PM   #2
Moderator Emeritus
 
Join Date: Nov 2008
Location: Winston-Salem, NC
Posts: 2,381
The answer to both question is yes, the truck will charge both. That is a long run for wiring, so make sure it is large, about 6 gauge or better. Tie them down good also, (not a bungee cord), as it is amazing how much bounce they will get on that hitch. Make sure also you don't bounce any acid out.
__________________

__________________
LadyWindrider
2012 Ford F250 ext. Cab 4x4
2002 Jeep Wrangler Sahara
2008 Yamaha V-Star 650 Classic

2008 Work and Play 18LT
LadyWindrider is offline   Reply With Quote
Old 08-31-2012, 03:57 PM   #3
Site Team - Lou
 
Herk7769's Avatar
 
Join Date: Oct 2009
Location: South Eastern PA
Posts: 22,436
Quote:
Originally Posted by windrider View Post
The answer to both question is yes, the truck will charge both. That is a long run for wiring, so make sure it is large, about 6 gauge or better. Tie them down good also, (not a bungee cord), as it is amazing how much bounce they will get on that hitch. Make sure also you don't bounce any acid out.
The standard charge wire in the Bargman 7 pin connector is heavy enough for your a 2 battery set up. No need to change anything.
__________________
Lou, Laura, & Freya the wonder dog
2008 GMC Sierra 3000HD Crewcab SB Allison Duramax
2019 Flagstaff 8529FLS - Pullrite 3300
HAM CALLSIGN - KC3FFW
Herk7769 is online now   Reply With Quote
Old 08-31-2012, 04:04 PM   #4
Mod free 5er
 
Join Date: Mar 2008
Location: Concord, NC
Posts: 24,704
Quote:
Originally Posted by herk7769 View Post
The standard charge wire in the Bargman 7 pin connector is heavy enough for your a 2 battery set up. No need to change anything.
X2, been using it for years that way.
__________________
OldCoot is offline   Reply With Quote
Old 08-31-2012, 04:20 PM   #5
Member
 
Join Date: May 2012
Posts: 93
Thanks guys, always appreciate the timely and accurate replies.
rmdrifter is offline   Reply With Quote
Old 08-31-2012, 05:35 PM   #6
Moderator Emeritus
 
Join Date: Nov 2008
Location: Winston-Salem, NC
Posts: 2,381
I was talking about a wire all the way under a camper. I assume a trailer, with battery in nose or on tongue. The battery would be hooked to the converter. Now, to add battery on the trailer hitch, again I assume that would be on the rear, over 20 feet of wire. That is where I was suggesting a large wire.

Agree, adding a larger wire to the trailer connector is useless, the contacts are the limiting factor on current.
__________________
LadyWindrider
2012 Ford F250 ext. Cab 4x4
2002 Jeep Wrangler Sahara
2008 Yamaha V-Star 650 Classic

2008 Work and Play 18LT
LadyWindrider is offline   Reply With Quote
Old 08-31-2012, 05:57 PM   #7
Member
 
Join Date: May 2012
Posts: 93
Actually plan is to move battery box on front of hitch over and slide in another box next to it with parallel wires--both should fit and will be mounted with 4 tap screws each through crossbars as is current box.
rmdrifter is offline   Reply With Quote
Old 08-31-2012, 05:58 PM   #8
Senior Member
 
Join Date: Jan 2012
Posts: 553
I put 2 Trojan 225's on my tongue on my SP189.

They fit in a Group 27 box - two of them, but it had to trim the boxes and the lids with a Dremel to get them to fit. Two group 24 boxes mayfit, but probably need to trim a bit too. Looked, but could not find a "double" box.

So I suggest doing some measuring first.
crasher is offline   Reply With Quote
Old 08-31-2012, 06:09 PM   #9
Member
 
Join Date: May 2012
Posts: 93
I'm using two 24s--smaller box size--which will be enough amps for my purposes. Also couldn't locate a dbl 24 box, only dbl 6V boxes available. I eyeballed and measured situation pretty carefully and think I can fit both boxes on front hitch of 186. Regardless, I'll make sure they are absolutely secure before taking off. Will complete project Sunday PM...will let Forum know if there are any mounting issues.
rmdrifter is offline   Reply With Quote
Old 08-31-2012, 06:36 PM   #10
Moderator Emeritus
 
Join Date: Nov 2008
Location: Winston-Salem, NC
Posts: 2,381
Now I get it. Just so you will know, the front of the trailer is the tongue, or the pin on a 5th wheel, not the hitch. The hitch would be on the back, like the one on your tow vehicle. Some campers do have them. Glad I'm not confused anymore, forget what I mentioned above.

As to your comment on post #9, "I'm using two 24s--smaller box size--which will be enough amps for my purposes." Parallel batteries don't give more amperage. You are still limited by the max amp hour per battery. The amps won't add, but the time will double, assuming two matched batteries.
In other words, 50 amp hours will still be 50 amp hours, it will just double the time to 2 hours, and then you will have two dead batteries.

Hope this makes sense.
__________________
LadyWindrider
2012 Ford F250 ext. Cab 4x4
2002 Jeep Wrangler Sahara
2008 Yamaha V-Star 650 Classic

2008 Work and Play 18LT
LadyWindrider is offline   Reply With Quote
Old 08-31-2012, 06:56 PM   #11
Site Team - Lou
 
Herk7769's Avatar
 
Join Date: Oct 2009
Location: South Eastern PA
Posts: 22,436
Quote:
Originally Posted by windrider View Post
Now I get it. Just so you will know, the front of the trailer is the tongue, or the pin on a 5th wheel, not the hitch. The hitch would be on the back, like the one on your tow vehicle. Some campers do have them. Glad I'm not confused anymore, forget what I mentioned above.

As to your comment on post #9, "I'm using two 24s--smaller box size--which will be enough amps for my purposes." Parallel batteries don't give more amperage. You are still limited by the max amp hour per battery. The amps won't add, but the time will double, assuming two matched batteries.
In other words, 50 amp hours will still be 50 amp hours, it will just double the time to 2 hours, and then you will have two dead batteries.

Hope this makes sense.
I think you need another beer my friend.

12 volt batteries in parallel doubles amp hours but not volts.
Two 6 volt batteries in series doubles voltage but not amp hours.

Two 50AH 12 volt batteries will provide 100 amp hours of capacity at 12 volts.
Attached Images
  
__________________
Lou, Laura, & Freya the wonder dog
2008 GMC Sierra 3000HD Crewcab SB Allison Duramax
2019 Flagstaff 8529FLS - Pullrite 3300
HAM CALLSIGN - KC3FFW
Herk7769 is online now   Reply With Quote
Old 08-31-2012, 07:16 PM   #12
Senior Member
 
lswartz's Avatar
 
Join Date: Jul 2012
Location: Maryland
Posts: 616
Quote:
Originally Posted by herk7769 View Post
I think you need another beer my friend.
If it is cold, I'd like one too.

I am having a heck of a time finding a container for my 2 6 volt golf cart batteries (& yes, you get 12 volts with the amp hours of the weakest battery). The Walmart battery boxes are not high enough for golf cart batteries. the same for their tool boxes. I am going to try a Rubber Maid box tomorrow & then visit Lowes and/or Home Depot. Maybe Sears as well. I may just have to find someone to weld some new angle iron on top of the hitch to give me some more space.
__________________
2013 Rockwood Mini Lite 2109S
2010 Toyota Tundra 4WD
lswartz is offline   Reply With Quote
Old 08-31-2012, 07:19 PM   #13
Site Team - Lou
 
Herk7769's Avatar
 
Join Date: Oct 2009
Location: South Eastern PA
Posts: 22,436
Quote:
Originally Posted by lswartz View Post
If it is cold, I'd like one too.

I am having a heck of a time finding a container for my 2 6 volt golf cart batteries (& yes, you get 12 volts with the amp hours of the weakest battery). The Walmart battery boxes are not high enough for golf cart batteries. the same for their tool boxes. I am going to try a Rubber Maid box tomorrow & then visit Lowes and/or Home Depot. Maybe Sears as well. I may just have to find someone to weld some new angle iron on top of the hitch to give me some more space.
I made my battery box out of two restaurant "bus" trays.
Attached Thumbnails
Click image for larger version

Name:	camper 005.jpg
Views:	110
Size:	59.1 KB
ID:	18962  
__________________
Lou, Laura, & Freya the wonder dog
2008 GMC Sierra 3000HD Crewcab SB Allison Duramax
2019 Flagstaff 8529FLS - Pullrite 3300
HAM CALLSIGN - KC3FFW
Herk7769 is online now   Reply With Quote
Old 08-31-2012, 07:27 PM   #14
Senior Member
 
lswartz's Avatar
 
Join Date: Jul 2012
Location: Maryland
Posts: 616
That is a nice clean setup. I don't have that kind of space but it would be nice to have them inside vs. on the hitch behind the propane tanks. It might be the trade off of a smaller trailer.
__________________
2013 Rockwood Mini Lite 2109S
2010 Toyota Tundra 4WD
lswartz is offline   Reply With Quote
Old 08-31-2012, 07:47 PM   #15
Site Team - Lou
 
Herk7769's Avatar
 
Join Date: Oct 2009
Location: South Eastern PA
Posts: 22,436
It is the front compartment of my 5th wheel.
It was all open when I bought it.
I built the power compartment out of plywood.
Attached Thumbnails
Click image for larger version

Name:	6 June 2009 016.jpg
Views:	76
Size:	56.4 KB
ID:	18966  
__________________
Lou, Laura, & Freya the wonder dog
2008 GMC Sierra 3000HD Crewcab SB Allison Duramax
2019 Flagstaff 8529FLS - Pullrite 3300
HAM CALLSIGN - KC3FFW
Herk7769 is online now   Reply With Quote
Old 09-01-2012, 02:45 PM   #16
Member
 
Join Date: May 2012
Posts: 93
Interesting comment Windrider, and thanks for the education on terms. All I'm interested in is doubling the time, so from what you indicate above using two batteries will achieve that end. Just curious though as to how it actually works: Do the batteries drain simultaneously and equally when wired parallel...correct assumption?
rmdrifter is offline   Reply With Quote
Old 09-01-2012, 04:22 PM   #17
Site Team - Lou
 
Herk7769's Avatar
 
Join Date: Oct 2009
Location: South Eastern PA
Posts: 22,436
Quote:
Originally Posted by rmdrifter View Post
Interesting comment Windrider, and thanks for the education on terms. All I'm interested in is doubling the time, so from what you indicate above using two batteries will achieve that end. Just curious though as to how it actually works: Do the batteries drain simultaneously and equally when wired parallel...correct assumption?
It actually depends on the batteries and how you wire them.

In order for them to work properly (charge and discharge together evenly) they must have equal resistance (including internal resistance) from the charge point to the ground point (called a "CELL".

In order for the internal resistance to be equal:
1) The batteries must be from the same manufacturer
2) The batteries must be the same type and size
3) The batteries must be the same AGE (the same number and depth of charge/discharge cycles)
So, buy them as a set and change them out as a set.

In order for the external resistance to be equal:
1) The red wire from the camper must go from the positive of the first battery in the cell and the ground wire must go to the last battery in the cell.
2) The inter connecting wires inside the cell MUST be identical in resistance. That is the SAME length, gauge, and termination (lugs).

This is so the charging and discharging current flows evenly through the stack of batteries. If the resistance in one battery is lower than the other (due to any violation of the above rules), the current into and out of that battery will be higher than the one with the higher resistance.

This will result in the lower resistance battery being discharged deeper than the other and be charged up faster that the one with higher resistance. As a result, the weaker battery will work harder; lose electrolyte every charge; and fail earlier. This effect will be worse the wider the resistance difference between the batteries.

Adding batteries to the cell beyond two must follow the same rules as above as shown in the top photo.
Attached Thumbnails
Click image for larger version

Name:	Battery Parralell Connections.jpg
Views:	67
Size:	49.9 KB
ID:	18999  
Attached Images
 
__________________
Lou, Laura, & Freya the wonder dog
2008 GMC Sierra 3000HD Crewcab SB Allison Duramax
2019 Flagstaff 8529FLS - Pullrite 3300
HAM CALLSIGN - KC3FFW
Herk7769 is online now   Reply With Quote
Old 09-01-2012, 05:13 PM   #18
Member
 
Join Date: May 2012
Posts: 93
Thanks Lou for taking the time to make such a detailed explanation--very clear.
rmdrifter is offline   Reply With Quote
Old 09-01-2012, 05:57 PM   #19
Senior Member
 
HONDAMAN174's Avatar
 
Join Date: Jun 2011
Location: Big brown desert
Posts: 2,716
So that's what I'm doing wrong. I have them hooked up wrong...again! I have both trailer leads coming off of one battery and the parallel cables hooked to the second. So I have one nearly dead unit and one fully charged at the end of dry camping. Thanks for the info!
__________________
2014 Stealth Evo 2850- "Woodstock"
2011 Toyota Tundra Rock Crawler TRD 5.7- "Clifford"
2013 Honda Accord Coupe V6 w/Track Pack- "Julia"

Just glad to get away
HONDAMAN174 is offline   Reply With Quote
Old 09-01-2012, 06:46 PM   #20
Site Team
 
bikendan's Avatar
 
Join Date: Jan 2007
Location: Camano Island, Washington
Posts: 19,252
if everyone visited the "12 volt Side of Life" website, where a lot of Herk's pics come from, there would be a lot less questions like this.
__________________

__________________
Dan-Retired California Firefighter/EMT
Shawn-Musician/Entrepreneur/Wine Expert
and Zoe the Wonder Dog(R.I.P.)
2016 PrimeTime TracerAIR 255, pushing a 2014 Ford F150 SCREW XTR 4x4 3.5 Ecoboost w/Max Tow Package
Equalizer WDH
bikendan is offline   Reply With Quote
Reply

Tags
12 volt, battery

Thread Tools
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



» Featured Campgrounds

Reviews provided by

Disclaimer:

This website is not affiliated with or endorsed by Forest River, Inc. or any of its affiliates. This is an independent, unofficial site.



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 09:29 AM.


×