Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×


Reply
 
Thread Tools Display Modes
Old 07-05-2022, 01:20 PM   #1
Junior Member
 
Join Date: May 2022
Posts: 16
Battery wiring wrong?

Hi,
See picture. Service added a second battery in parallel for us and connected the RV pos and neg to ONE battery. 90% of what I’ve read says the pos and neg should be connected to separate batteries, for charging balance and efficiency. I have read a few places saying it doesn’t really matter, the difference is negligible.

And, if I needed to charge the batteries where would I attach the charger pos neg clamps in the current configuration? To the one battery with the rv connection?

Help with this?
Thank you.
Attached Thumbnails
Click image for larger version

Name:	48774311-E143-4F63-9EFA-8E8FFCDF0106.jpg
Views:	61
Size:	506.5 KB
ID:	275980  
Tony 260DS is offline   Reply With Quote
Old 07-05-2022, 01:33 PM   #2
Senior Member
 
Join Date: Jul 2017
Location: North of Seattle, WA
Posts: 14,860
Unless you are discharging and charging at HIGH current levels the difference IS negligible.

At the discharge/charge levels present in MOST RV's when using batteries, worrying about how the batteries are connected is like "picking fly poop out of ground pepper".

As long as 12 volt batteries are connected in parallel and 6 volt batteries are connected in series to produce 12 volts, that's what is important.

Use the largest wire size that's practical to connect batteries in parallel and all is good.
__________________
"A wise man can change his mind. A fool never will." (Japanese Proverb)

"You only grow old when you run out of new things to do"

2018 Flagstaff Micro Lite 25BDS
2004 Nissan Titan
TitanMike is offline   Reply With Quote
Old 07-05-2022, 11:19 PM   #3
Junior Member
 
Join Date: May 2022
Posts: 16
Quote:
Originally Posted by TitanMike View Post
Unless you are discharging and charging at HIGH current levels the difference IS negligible.

At the discharge/charge levels present in MOST RV's when using batteries, worrying about how the batteries are connected is like "picking fly poop out of ground pepper".

As long as 12 volt batteries are connected in parallel and 6 volt batteries are connected in series to produce 12 volts, that's what is important.

Use the largest wire size that's practical to connect batteries in parallel and all is good.
Thanks for the feedback and thanks for the LOL on that quote.
Tony 260DS is offline   Reply With Quote
Old 07-06-2022, 12:39 AM   #4
Senior Member
 
rsdata's Avatar
 
Join Date: Aug 2014
Location: Northern KY
Posts: 5,535
Quote:
Originally Posted by Tony 260DS View Post
Hi,
See picture. Service added a second battery in parallel for us and connected the RV pos and neg to ONE battery. 90% of what I’ve read says the pos and neg should be connected to separate batteries, for charging balance and efficiency. I have read a few places saying it doesn’t really matter, the difference is negligible.

And, if I needed to charge the batteries where would I attach the charger pos neg clamps in the current configuration? To the one battery with the rv connection?

Help with this?
Thank you.
although it is too late to do anything about it now, for future reference two batteries in parallel should be the exact same make and age... as you now have it the weakest and/or oldest battery will always pull the better of the two batteries down ... to whatever level of performance is the lowest common denominator

when charging always hook POS to POS and NEG to NEG... any battery post in any configuration will be the same according to the wiring of parallel batteries...

check this out
https://batteryguy.com/kb/knowledge-...s-in-parallel/
__________________
"nothing can now be believed which is seen in a newspaper. Truth itself becomes suspicious by being put into that polluted vehicle."
Thomas Jefferson to John Norvell pg. 2, June 11, 1807

2014 Shamrock 183
2014 RAM 1500 Bighorn Crew Cab, HEMI, 3.21 gears, 8 Spd, 4X4 TST TPMS
rsdata is offline   Reply With Quote
Old 07-06-2022, 02:40 AM   #5
Senior Member
 
nvs4602's Avatar
 
Join Date: Jan 2019
Posts: 549
The best way to wire them is to put the negative lead on 1 battery athe possible lead wire on the 2nd battery. Then both batteries will charge at the same rate. That will compensate for any resistance in wiring between the 2 batteries.
nvs4602 is offline   Reply With Quote
Old 07-06-2022, 06:21 AM   #6
Senior Member
 
TowPro's Avatar
 
Join Date: Sep 2019
Posts: 1,412
what you got is fine, we are not wiring rocket ships here, its an RV. There is so little resistance in those hookup wires it don't matter.

The time you see a wire on each battery is when they hook Two 6 volt batters (golf cart) up in series to make 12V.
__________________
No RV currently
TowPro is offline   Reply With Quote
Old 07-06-2022, 06:42 AM   #7
Senior Member
 
Join Date: May 2020
Posts: 335
If it bothers you, and it would bother me, move the positive cable to the other battery.
__________________

2006 Dynamax Isata IE 250
420 Ah batteries
400w Solar
eric1514 is offline   Reply With Quote
Old 07-06-2022, 08:04 AM   #8
Site Team
 
Flybob's Avatar
 
Join Date: Oct 2014
Posts: 14,184
The fact that you have differences in batteries is more significant than the wiring scheme, but for an RV you will likely not see any impact.
__________________

2015 Freedom Express 248RBS
TV 2015 Silverado HD2500 Duramax
TST Tire Monitors
Honda 2000I + Companion
2 100W solar panels
Flybob is offline   Reply With Quote
Old 07-06-2022, 08:12 AM   #9
Senior Member
 
Join Date: May 2020
Posts: 335
And perhaps moving the cable would help mitigate those differences.
__________________

2006 Dynamax Isata IE 250
420 Ah batteries
400w Solar
eric1514 is offline   Reply With Quote
Old 07-06-2022, 08:33 AM   #10
Senior Member
 
Chuck_S's Avatar
 
Join Date: Aug 2018
Location: Richmond VA
Posts: 3,139
It's not that hard to connect correctly but it may take 5 minutes...



-- Chuck
__________________
2006 Roo 23SS behind a 2017 Ford Expedition
Chuck_S is offline   Reply With Quote
Old 07-06-2022, 08:38 AM   #11
Pickin', Campin', Mason
 
5picker's Avatar
 
Join Date: Aug 2015
Location: South Western PA
Posts: 16,068
Quote:
Originally Posted by TitanMike View Post
Unless you are discharging and charging at HIGH current levels the difference IS negligible.

At the discharge/charge levels present in MOST RV's when using batteries, worrying about how the batteries are connected is like "picking fly poop out of ground pepper".

As long as 12 volt batteries are connected in parallel and 6 volt batteries are connected in series to produce 12 volts, that's what is important.

Use the largest wire size that's practical to connect batteries in parallel and all is good.
X2

The voltage/amperage loss in that less than one foot of heavy battery cable is negligible and you will not see a difference in performance or life of the battery.(ies)
__________________
_________________________________________
2016 Flagstaff 8529IKBS Diamond Package 5th Wheel•Goodyear Endurance Tires•2017 Ford F-Series SCREW 4x4•Factory Puck•B&W Companion•TST Tire Monitor w/Repeater•Sinemate 3500w Gen.
F&AM Lodge 358 Somerset, PA - JAFFA Shrine - Altoona, PA

Days Camped: '17=38 '18=49 '19=58 '20=110 '21=116 '22=90
5picker is offline   Reply With Quote
Old 07-06-2022, 08:43 AM   #12
Senior Member
 
Join Date: Jul 2017
Location: North of Seattle, WA
Posts: 14,860
Quote:
Originally Posted by TowPro View Post
what you got is fine, we are not wiring rocket ships here, its an RV. There is so little resistance in those hookup wires it don't matter.

The time you see a wire on each battery is when they hook Two 6 volt batters (golf cart) up in series to make 12V.
Something that's hard for many to grasp because they saw a wiring diagram on an RV Blog, etc, etc, etc.

When using a heavy gauge wire (the larger the better) as you said, there is so little resistance it doesn't matter.

Same for worrying about equal length jumper wires, etc.

Then again, if one is wiring batteries with SMALL wires, then it might make a difference but in that case there are other issues far more important. For charging, when the batteries approach full charge the current drops and they will all reach the same voltage/state of charge, even if wired with 16 ga wire connected on the "same side".
__________________
"A wise man can change his mind. A fool never will." (Japanese Proverb)

"You only grow old when you run out of new things to do"

2018 Flagstaff Micro Lite 25BDS
2004 Nissan Titan
TitanMike is offline   Reply With Quote
Old 07-06-2022, 10:10 AM   #13
Senior Member
 
Join Date: May 2020
Posts: 335
Quote:
Originally Posted by TitanMike View Post
Something that's hard for many to grasp because they saw a wiring diagram on an RV Blog, etc, etc, etc.

When using a heavy gauge wire (the larger the better) as you said, there is so little resistance it doesn't matter.

Same for worrying about equal length jumper wires, etc.

Then again, if one is wiring batteries with SMALL wires, then it might make a difference but in that case there are other issues far more important. For charging, when the batteries approach full charge the current drops and they will all reach the same voltage/state of charge, even if wired with 16 ga wire connected on the "same side".
All true, but we know that moving that positive cable to the other battery is the correct thing to do whether it’s theoretical or not, and since it would take 5 minutes to do including stopping for a beer break, why not just go ahead a get it done.
__________________

2006 Dynamax Isata IE 250
420 Ah batteries
400w Solar
eric1514 is offline   Reply With Quote
Old 07-06-2022, 10:25 AM   #14
Senior Member
 
NMWildcat's Avatar
 
Join Date: Jun 2012
Location: Southern NM
Posts: 8,115
Quote:
Originally Posted by eric1514 View Post
All true, but we know that moving that positive cable to the other battery is the correct thing to do whether it’s theoretical or not, and since it would take 5 minutes to do including stopping for a beer break, why not just go ahead a get it done.
Because it really does NOT matter in this case. The only change would be to make you feel better...
__________________
Scott and Liz - Southern NM
2012 Wildcat Sterling 32RL - w/level up (best option ever)
2007 Chevy 2500HD 4dr short bed Duramax w/allison
Reese Fifth Airborne air ride king pin coupler with Sidewinder
NMWildcat is offline   Reply With Quote
Old 07-06-2022, 12:19 PM   #15
Canadian Member
 
Join Date: Feb 2012
Location: Eastern GTA, Ontario, Canada
Posts: 5,911
Quote:
Originally Posted by eric1514 View Post
If it bothers you, and it would bother me, move the positive cable to the other battery.
Me, too. I’m a bit of a perfectionist and it would bother me even though, as others said, it doesn’t make much difference in performance for the OP’s situation. I like to form good habits and do it the proper way. Heck, I’d be bothered by having two different-aged 12V batteries.
__________________
2019 Rockwood Signature 8290BS, Reese Revolution pinbox, B&W Patriot 18K hitch
2016 Ford F-250 XLT SuperCrew, 6.2L, 4x4, 6'9" bed, 3.73, w/ snow plow & camper pkgs.
2011 Rockwood Signature 8293SS (2015 - 2018)
2010 Rockwood Roo 23SS (2012 - 2014)

itat is offline   Reply With Quote
Old 07-06-2022, 01:21 PM   #16
Senior Member
 
Join Date: Jul 2017
Location: North of Seattle, WA
Posts: 14,860
Quote:
Originally Posted by eric1514 View Post
All true, but we know that moving that positive cable to the other battery is the correct thing to do whether it’s theoretical or not, and since it would take 5 minutes to do including stopping for a beer break, why not just go ahead a get it done.
I agree that one could do it if they want but the latin term for this is "de minimis - lacking significance or importance: so minor as to merit disregard"

Those that are insistent that this is the ONLY proper way overlook the fact that sometimes the extra length of wire necessary merely contributes to the "rat's nest' effect and it's contribution to performance is 'de minimis'.

FWIW, if you have a large number of batteries connected into a large bank like in a Fork Lift, Off Grid Solar System, or maybe a 'Diesel Electric Submarine, where discharge and charging currents are in the hundreds of amperes, then wiring so electrical paths on the positive and negative sides of batteries are equal length (translated into equal resistance on each side) THAT's when this wiring strategy becomes important.

With half a dozen batteries in an RV, being charged with a 50-60 amp converter charger, way too much over-thought going into it.

More important is having matched batteries and charging for more than "a couple hours in the morning and a couple hours in the evening".
__________________
"A wise man can change his mind. A fool never will." (Japanese Proverb)

"You only grow old when you run out of new things to do"

2018 Flagstaff Micro Lite 25BDS
2004 Nissan Titan
TitanMike is offline   Reply With Quote
Reply

Tags
battery, wiring

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.



All times are GMT -5. The time now is 02:42 AM.