12v battery wiring, not series or parallel, but...

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TrailerTrucker

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Hello all RVers,

Thanks in advance for your help!  We recently bought a used 2010 Lance trailer, and found the batteries are wired like the attached picture...which I think is neither series nor parallel, but something just plain wrong.  I took it on a two-week trip, and it did just fine, but seemed to draw down pretty quick, though that was my first trip and I have little experience on how long these batteries should last.

Can anyone share what this wiring would actually do to my batteries and my capacity? Thanks so much


 

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TrailerTrucker said:
Hello all RVers,

Thanks in advance for your help!  We recently bought a used 2010 Lance trailer, and found the batteries are wired like the attached picture...which I think is neither series nor parallel, but something just plain wrong.  I took it on a two-week trip, and it did just fine, but seemed to draw down pretty quick, though that was my first trip and I have little experience on how long these batteries should last.

Can anyone share what this wiring would actually do to my batteries and my capacity? Thanks so much
Click to expand...

How old are batteries?  Draw down pretty quick?  What were you running.  A couple lights and a propane fridge, one thing.  Furnace, a whole different story.

Parallel wired as they are, keeps the system 12 vDc.  Just adds 2X the length they will last. (in theory)
 
They are in parallel, but wired wrong, they should feed corner to corner, not with the load positive and negative on the same battery.  Having it wired like this one battery will lag behind the other charging or discharging.  The simplest corrective action would be to move either the positive or negative feed to the other battery in the set.
 
Isaac-1 said:
They are in parallel, but wired wrong, they should feed corner to corner, not with the load positive and negative on the same battery.  Having it wired like this one battery will lag behind the other charging or discharging.  The simplest corrective action would be to move either the positive or negative feed to the other battery in the set.
Click to expand...

Huh? What did I miss here? Please post a drawing of what you mean.
 
Correct 12V parallel wiring should connect the positive on one battery and negative on the other to the main load leads like this:



https://i.pinimg.com/originals/0f/9a/e2/0f9ae223150f2f55fb5ab86a007892cd.gif
 
Issac-1 is correct

Wired 'as is' will work, but as Issac-1 states, his drawing and recommendation is the preferred and correct way.

Good catch  :))
 
Gotcha! I couldn't picture in my mind what was being said. Thanx.  :))
 
SpencerPJ said:
Issac-1 is correct

Wired 'as is' will work, but as Issac-1 states, his drawing and recommendation is the preferred and correct way.

Good catch  :))
Click to expand...
Yep, Issac is correct. It is not a huge problem with only two batteries but with a few more batteries in the circuit and it would really cut down on the amount of power it could hold.
 
Standard parallel wiring.. I have seen that Corner (positive load to one negative load the other) but unless you are drawing over 100 amps (inverter draw) I'd not fret about that. That is proper Parallel wiring for most RVs.

Now. suggestion.. when it comes time to replace.. (not until) if they fit go to GC-2 in series

-{6v}+===-{tv}+==12 volts

in this config the amp-hour capacity does not add (220 amp hours. mroe than you likely have now) but the voltage does. and you can use more of the power without flattening the batteries. (Flat means put in new ones as opposed to recharge).
 
Thanks so much everyone, and yes, Isaac, that's what I was thinking as well.  All of the parallel wiring diagrams I have seen have the wires leading to the load coming off of both batteries (one off of each) as opposed to the same battery, like my batteries are....I just have zero electrical background and no idea if that had any negative implications. 

And I think I will be switching over to a two battery GC2 system, as we're about to head off on a 5 month trip in the trailer and plan on doing some significant boondocking.  Looking at getting 200-300w of panels to feed the batteries and maybe a 1000w or smaller inverter.


Thanks again, y'all are awesome!
 
Isaac-1 is correct, that is also the way you should connect any permanent charging system ie solar. Direct parallel will not damage anything but it will favour the lead (as in dog lead) battery and then the second battery equalises charge. By splitting draw off using positive from one and negative from the other, current draw is balanced.
regards
TonyL
 
Trailer Trucker,
If you do not know the age and condition of that pair of batteries, then changing them out is a good plan.  There is another problem with batteries in parallel.  Unless the two jars are absolutely Identical (and they never are) you do not get capacity X 2.  If they are 6V jars in series, you get the Amp-Hour capacity of one, but at 12V.   
If you are going to add solar, (an idea with some merit) also include a real battery monitor.  This is not a voltmeter, but a power charge/use accumulation monitor.  They are not cheap, but when living on solar, they are essential. 

Matt 
   
 
One comment about the "Corner" Hookup (The person who said they are hooked up wrong)

The "Theory" is that with both positive and negative RV leads hooked to one battery that battery will bear the Brunt of the load/charge

The fact.. often the wires off to the RV are like 10 Ga or so..but the parallel cables (Battery to battery) are generally automotive starter cable (4ga or heavier) so if you ever notice a difference in the amount of current the batteries are supplying.... I'll be surprised.

Now with a big (IE 1KW or larger) inverter.. THEN hooking positive lead to one battery and negative to other makes sense. but that's the only case 

And if you decide to go the GC-2 Route (Which I suggest for multiple reasons including price)

Well each PAIR of 6 volt Golf car batteries wired in series (-bat+-ery+) is the same as one BIG 12 volt b attery (4d if you want to get literal)  Just hook up up line I typed it in prens. and treat the pair as though it were a SINGLE 4D battery.
 
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