Battery Box wiring help requested

[StarEcho]

I've been working on a battery box for underneath the bed in my trailer for at least 6 months off an on, mostly in the planning stages.  So now I finally got my butt in gear and got most of the items I needed to make the box the way it would work best for me.  At least I thought.

Now I know that there is the issue of offgassing when the batteries are being charged.  I think the bed seals itself pretty well to the bed frame and under the bed is the storage opening to the outside of the trailer, so there is plenty of ventilation.   I still wanted to make some type of compartment for my 4x6v golf cart batteries  and organize my wiring so I can fix things more easily.

So this is what I've had for the past 8 months or so:

[img=800x450]https://lh3.googleusercontent.com/s...x53e2nHfTiCfF5wGCjovPuyy3=w1202-h676-no[/img]

that board dividing the batteries from the rest of the compartment is just a freestanding board that seems to work ok, but it was never meant to be permanent.

So I decided to use a tough plastic tote for my box mainly because of finances.

[img=500x889]https://lh3.googleusercontent.com/T...culZxMrZ4BcNI6JVDM9qUg2f4X=w381-h676-no[/img]

Here's what it looks like with the batteries in it:

[img=600x337]https://lh3.googleusercontent.com/T...OokbEACryxYeaAF4-92KHg9wc=w1202-h676-no[/img]

I drilled a hole in the front of the trailer and put one of the battery box vents on it, attached the hose to the other side of the white pvc pipe piece you see on the top right of the picture.  The smaller tube goes to the bottom of the box, with my theory being that air would be heavier and go down to the bottom of the box to circulate around the batteries with the hydrogen and whatnot being heaver and flowing out the vent.

The bolts you see on the front of the box are the firewall bolts so that I only need to connect the battery wires inside the box and then one set to the inside of those firewall bolts and then everything else will attach to the outside set of firewall bolts.  The basic goal is to have everything that I need to access or might want to access on the outside of the box.  I set up a battery watering system to fulfill that wish as well.

[img=600x337]https://lh3.googleusercontent.com/M...ejjQuEz52FMSjcbH5aFyGPVaj=w1202-h676-no[/img]

The tubing runs out the right side of the box ----

[img=600x337]https://lh3.googleusercontent.com/X...eoakWqJLTSx_RCSoOp0wWa_-J=w1202-h676-no[/img]

And through the grommet.  I plan to put some sealant where I didn't get a perfect fit.

[img=600x337]https://lh3.googleusercontent.com/W...VqwJ6vC0LJ_EbOfViUxBTggfc=w1202-h676-no[/img]

Ok, so what's the problem?  Where is the question?  LOL  Well, in all my planning, I didn't take into account the wires from the inverter and trailer to the battery box.  They fit perfectly where the batteries were located before, but where I put the firewall bolts is about 2-3 ft or so farther away.


[img=600x337]https://lh3.googleusercontent.com/U...0NWVAJ-LAlFT7z09C3ZNDFnFw=w1202-h676-no[/img]
First of all, I had help before -- ok, friends from the winter did it for me-- Kirk cut the trailer wire to fit and added the lug nuts.  I don't understand why the inverter positive wire is doubled?

[img=400x712]https://lh3.googleusercontent.com/v...PkgUfF59ZvcYTQB9Ibvl3no3WT=w381-h676-no[/img]

I'm not sure what to do now, other than some type of connector.  1 ) Cut the lug nuts off, put the trailer wires into positive and negative bussbars and then another stretch of wire to go from the bussbars to the firewall bolts?  I don't have any tools to put lug nuts on wire that big.

2)  Why is the inverter positive wire doubled?  If there is such a solution as I've guessed above, how do I deal with that?

I do have a fuse on the outside of the trailer for those trailer wires.  And I got a fuse panel for all my internal 12 volt stuff. The wires from the charge controller are long enough I believe and if they are not I know how to handle them.

2) I'm also toying with the idea of cutting a hole in the side of the plastic box and putting that computer fan in there and wiring it to my solar panel "load" inputs so that it only runs dawn to dusk (while the batteries are being charged)  Is that necessary?  I'm worried that since I'm trying to make it airtight so that doesn't leak fumes, that will also do away with a lot of the natural ventilation of an rv storage bay.  Or will the ventilation tube be enough for that?

Ok, fire away.  Just please lets go with the assumption that I'm not overly worried about outgassing but more want this to add a measure of orderliness and ease of access to my setup.  On the other hand if you see anything that is absolutely horribly wrong please tell me.

Thanks for the help.

 

[DannyB1954]

I couldn't get your pictures to load, so I will try to address what I think I know. " with the hydrogen and whatnot being heaver and flowing out the vent" Hydrogen is lighter than air. They used it to lift blimps until the Hindenberg. If the batteries are off gassing, they will probably be warm. Their own heat might be enough to create air flow. If you use a fan for circulation it would be best if the fan did not create any internal sparks. I would also blow air into the box instead of out. That way the fan would be in fresh air.

Here is a black tank vent cover that uses any kind of breeze to suck out fumes. http://www.etrailer.com/RV-Vents-an...tml?feed=npn&gclid=CN7cy86UtM8CFQuqaQodr98LSw If you plumbed this into the top of your battery compartment it might help. During the winter that compartment may get cold if your bed is directly above it I would insulate.

 

[Optimistic Paranoid]

When you're charging batteries, especially if you are equalizing batteries, you are not only off-gassing hydrogen (flammable for sure, and I think potentially explosive, but only if the air/hydrogen mix is just right) you are also off-gassing corrosive sulfuric acid fumes.  I've seen threads in the mainstream RV forums where people complain about the steel in their battery compartments losing all the paint and rusting due to the fumes.

BTW, I couldn't see the pictures either.

 

[StarEcho]

hmm, wonder why the pics don't show?  Obviously they show for me.... They are from my google photos, so maybe it's something with permissions.  I put them all in a shared album now so here is that link

https://goo.gl/photos/oVNA6rRseNqaeTda9

The hydrogen being lighter was what I meant.  The air is heaver so it will fall to the bottom and the hydrogen will go out the vent.  Sometimes my fingers type their own thing. lol  and the fan was meant to blow INTO the box.  My question for that was is it necessary and would that compromise the idea of gasses getting into the bed compartment.  My guess is not since there is a vent higher up for the hydrogen to flow out so if I put the fan on the bottom of the box only air would flow out when it was off?

Not worried about the underbed / outside accessible storage being cold in winter.  It didn't make a difference last winter, so that's not an issue.  I think if you can see the pictures you'll understand what I mean.  Sorry they didn't show up.

My main concern was how to connect the large diameter wires with the available supplies.  IE is it possible to work this out without having to order from Amazon yet again and wait another 3 or 4 days.  Cause yes, even with 2 day shipping, that doesn't count weekends and the day you order.

Maybe I'll just take the firewall bolts out and move them to the side where the trailer and inverter connections are, just to be done with it.  That makes it not "pretty" with the two holes in the front that I will have to patch somehow.  But at least it will be done and I can get on with the rest of the project of hard wiring many of my 12v items with their own fuses, and outside 12v outlets, etc.

Please let me know if you still can't see the pics and I'll just upload them here as attachments.

Thanks for trying to help.  I know it's almost impossible when you can see what I'm talking about.

 

[StarEcho]

Ah another question...

I should have my solar panels fused before they get to the battery right?  Or wrong?  They are not fused now, and I've been lucky with no problems, but if I'm mucking about with distribution panels and whatnot, I might as well get those right.  So I have a terminal fuse block

https://www.amazon.com/gp/product/B0019ZBTV4/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

with a 30 amp fuse to go in it, that I thought I'd add from the charge controller to the + side of the outside firewall bolts.  

Is that the proper place or do they need to be fused BEFORE the charge controller?  And if so, then do I need to get yet another doodad to accomplish that?  If so can you give an idea of what to search for?

Thanks again.

 

[SternWake]

I saw the embedded pics last night but now they do not show.

The inverter cables for a 2000 watt inverter should be thick, like 2/0 gauge or fatter.  It appears(ed) your current inverter (+) cable is doubled 6awg cable. and the (-) is 4awg

To actually approach 1000 watt output you need fatter cabling, much less 2000.

The appearance of electrical tape on the ring terminals might also indicate crimps of dubious quality.

Properly making  thicker battery cables takes more than a hammer and a vice and electrical tape.
 
This guy makes top quality custom cables with top quality parts for a great price and fast and free shipping. Much much better than auto parts store bought cables and for often less money.
 
http://www.genuinedealz.com/custom-cables

Use ring terminals with center holes just large enough to fit over studs and no larger.  Order them small if you have to and drill them afterwards to fit if you have to.  You do not want the ring terminal to be a sloppy fit over the stud.

Please skim through this link regarding the making of proper battery cables:
http://www.pbase.com/mainecruising/battery_cables

Flooded/wet Batteries will start offgassing during charging, when they get in the 14.2 v range, they will then continue to gass as long as voltages this high or higher are held by the charging source.  Higher amperage charge rates to reach absorption voltage will cause more offgassing. Very high discharge rates, like 2000 watts, will also cause offgassing.

Electrolysis produces oxygen and hydrogen and takes a slight sulfuric acid mist with it.  The gasses are warm and will rise, and obviously hydrogen rises, and both hydrogen and oxygen are combustible.

So a perfectly sealed box  filled with charging batteries, is basically a bomb, waiting for a spark. 

If air is exhausted, air must be replaced too. Exhaust high, intake low.

Huge volumes of air movement are not required, but I can easily smell a charging flooded battery that is offgassing and will not inhabit the same space as one.

Offgassing has to happen for a flooded battery to reach full charge, do not listen to those who say a properly charged battery will not offgass. Others have no issue with sulfuric acid mist, or can't smell it, and scoff at the possible risk.

And the next person who says a battery boils is going to get a digital slap upside the head.

100% Sulfuric acid boils at 638.6 degrees f, and even diluted to 1.250 specific gravity would start boiling after the battery case has begin melting at 220F+.

 

[Optimistic Paranoid]

A couple of comments. 

Every well designed battery box I've ever seen has two holes, one up high as the exit, and one down low, on the opposite side, for the air intake.  I'm actually not sure if that clear tube you've got coming in from the outside will actually work as an air intake or not.  For sure it will probably SLOW DOWN the rate of air exchange.   Which may, or may not, be a bad thing.  Depending on how much total air exchange occurs.  All I can really say is it's not "best design practice".

As far as the doubled wires, that doubles the ampacity - or in simple non electrical engineering English - doubles the current capacity of the circuit.  If you use two thin wires instead of one thick wire, it tends to be more flexible and easier to bend around corners and so on.  Or your friend may have done it that way because he already had the thin wire, and he was trying to save you some money by not buying the thicker wire.

Hope that helps.

Edit:  Just saw where Sternwake beat me to it while I was typing.

 

[StarEcho]

I saw the embedded pics last night but now they do not show.  

Ok, if I have time I'll repost the first post with attached pics.  Maybe it's a size issue or something.

The inverter cables for a 2000 watt inverter should be thick, like 2/0 gauge or fatter.  It appears(ed) your current inverter (+) cable is doubled 6awg cable. and the (-) is 4awg

To actually approach 1000 watt output you need fatter cabling, much less 2000.

The appearance of electrical tape on the ring terminals might also indicate crimps of dubious quality.

Properly making  thicker battery cables takes more than a hammer and a vice and electrical tape.

The inverter cables came with the inverter, so one would ASSUME (LOL) that they were correct.  Oh well.  I will order from the link you gave.  Question though:  Do I need to order 2AWG for both positive AND negative, or can I just order a 2AWG for the positive and keep the existing negative?

This guy makes top quality custom cables with top quality parts for a great price and fast and free shipping. Much much better than auto parts store bought cables and for often less money.
 
http://www.genuinedealz.com/custom-cables

Use ring terminals with center holes just large enough to fit over studs and no larger.  Order them small if you have to and drill them afterwards to fit if you have to.  You do not want the ring terminal to be a sloppy fit over the stud.

Please skim through this link regarding the making of proper battery cables:
http://www.pbase.com/mainecruising/battery_cables

Thanks for the link.  I will use it.  However, I won't be making any battery cables.  I don't have the equipment or strength to use it, so that will have to be ordered or done by friends.  Thanks for the info though.

Flooded/wet Batteries will start offgassing during charging, when they get in the 14.2 v range, they will then continue to gass as long as voltages this high or higher are held by the charging source.  Higher amperage charge rates to reach absorption voltage will cause more offgassing. Very high discharge rates, like 2000 watts, will also cause offgassing.

Electrolysis produces oxygen and hydrogen and takes a slight sulfuric acid mist with it.  The gasses are warm and will rise, and obviously hydrogen rises, and both hydrogen and oxygen are combustible.

So a perfectly sealed box  filled with charging batteries, is basically a bomb, waiting for a spark. 

If air is exhausted, air must be replaced too. Exhaust high, intake low.

Huge volumes of air movement are not required, but I can easily smell a charging flooded battery that is offgassing and will not inhabit the same space as one.

Offgassing has to happen for a flooded battery to reach full charge, do not listen to those who say a properly charged battery will not offgass. Others have no issue with sulfuric acid mist, or can't smell it, and scoff at the possible risk.

And the next person who says a battery boils is going to get a digital slap upside the head.

100% Sulfuric acid boils at 638.6 degrees f, and even diluted to 1.250 specific gravity would start boiling after the battery case has begin melting at 220F+.

Ok, you have to be specific with me.  What exactly are you saying in regards to my questions?  

What I'm getting is that I don't want a perfectly sealed box which I already understand.  Hence the vent to the outside of the trailer.  The exhaust is the larger diameter pvc pipe and the intake is the smaller diameter clear tubing that goes to the bottom of the box.  So check and check.  

If you're implying that I should have had a battery box from the beginning, well duh!  LOL  But it is what it is.  I didn't have the big bucks to have someone fabricate a metal box for me. 

Now was offgassing a problem?  I could definitely smell it when the bed was up, but not when the bed was down, so the bed obviously has a good seal with the bed frame.  Was there ventilation before?  Yes most definitely.  That compartment door from the outside of the trailer is NOT well sealed and air goes in and out of the edges quite well. Basically that whole underbed storage compartment WAS a giant battery box.  

Does any gas escape into the living area?  Maybe, I don't know.  All I know is that it is what it is and I'm working on trying to make it safer now.  I'm not losing sleep over it though.  

Other than that I'm not sure what you are trying to say here?

In any case, I do appreciate your comments SternWake!  Thanks!

 

[StarEcho]

Every well designed battery box I've ever seen has two holes, one up high as the exit, and one down low, on the opposite side, for the air intake.  I'm actually not sure if that clear tube you've got coming in from the outside will actually work as an air intake or not.  For sure it will probably SLOW DOWN the rate of air exchange.   Which may, or may not, be a bad thing.  Depending on how much total air exchange occurs.  All I can really say is it's not "best design practice".

Well, I've seen a lot of diagrams on battery boxes and this design made the most sense to me.  I only wanted one vent hole on my trailer.  And I can't see any reason in the world why air would not go through the clear tubing to the bottom of the box.  For sure any gasses would go through the larger pvc pipe OUT.  Now if I were made of money the pipe and tubing would have been copper.  But I'm not and they are not.  The principle is the same, though isn't it?  Air is heavier and will flow DOWN and the off gasses are lighter and will flow UP and out the vent pipe?  I think the only issue that copper address is temperature differentials?  Now maybe that sounds like I know what I'm talking about but it's really only what I've read and mostly understand so I'm open to education.

As far as the doubled wires, that doubles the ampacity - or in simple non electrical engineering English - doubles the current capacity of the circuit.  If you use two thin wires instead of one thick wire, it tends to be more flexible and easier to bend around corners and so on.  Or your friend may have done it that way because he already had the thin wire, and he was trying to save you some money by not buying the thicker wire.

Yes, that does make sense, thanks and explains a lot.  Just to be clear though, my friend did NOT make that inverter cable, that came from Amazon that way with the inverter itself.

That OP for responding, I appreciate it.  If you can give me an explanation for why the design I chose won't work (other than it's not what you're used to) I'd also appreciate that.

 

[StarEcho]

Ok, this is a repost/edit of the first post in this thread with five pictures "attached" instead of embedded.  The only question from this thread that I don't think was answered or discussed was the first question about connecting two large gauge wires so as to increase the length.  Without redoing the whole wire as I don't have any way to add lugnuts.  I don't have the tools or the strength.

Other than that, this post is just for the pictures.

I've been working on a battery box for underneath the bed in my trailer for at least 6 months off an on, mostly in the planning stages.  So now I finally got my butt in gear and got most of the items I needed to make the box the way it would work best for me.  At least I thought.

Now I know that there is the issue of offgassing when the batteries are being charged.  I think the bed seals itself pretty well to the bed frame and under the bed is the storage opening to the outside of the trailer, so there is plenty of ventilation.   I still wanted to make some type of compartment for my 4x6v golf cart batteries  and organize my wiring so I can fix things more easily.

So this is what I've had for the past 8 months or so:

View attachment 9557

that board dividing the batteries from the rest of the compartment is just a freestanding board that seems to work ok, but it was never meant to be permanent.

So I decided to use a tough plastic tote for my box mainly because of finances.  [added] I haven't had any problems in 8 months with leaking or discharge so I'm not overly worried about acid eating away at it, but I'll keep an eye on it.

Here's what it looks like with the batteries in it:

View attachment 9564

I drilled a hole in the front of the trailer and put one of the battery box vents on it, attached the hose to the other side of the white pvc pipe piece you see on the top right of the picture.  The smaller tube goes to the bottom of the box, with my theory being that air would be heavier and go down to the bottom of the box to circulate around the batteries with the hydrogen and whatnot being heaver and flowing out the vent.

The bolts you see on the front of the box are the firewall bolts so that I only need to connect the battery wires inside the box and then one set to the inside of those firewall bolts and then everything else will attach to the outside set of firewall bolts.  The basic goal is to have everything that I need to access or might want to access on the outside of the box.  I set up a battery watering system to fulfill that wish as well.

The tubing runs out the right side of the box ----

And through the grommet.  I plan to put some sealant where I didn't get a perfect fit.

View attachment 9565

Ok, so what's the problem?  Where is the question?  LOL  Well, in all my planning, I didn't take into account the wires from the inverter and trailer to the battery box.  They fit perfectly where the batteries were located before, but where I put the firewall bolts is about 2-3 ft or so farther away. -- See the first picture. --

First of all, I had help before -- ok, friends from the winter did it for me-- Kirk cut the trailer wire to fit and added the lug nuts.  
But I don't understand why the inverter positive wire is doubled? [edit] (came with the inverter that way)

View attachment 9566

I'm not sure what to do now, other than some type of connector.

 1 ) Cut the lug nuts off, put the trailer wires into positive and negative bussbars and then another stretch of wire to go from the bussbars to the firewall bolts?  I don't have any tools to put lug nuts on wire that big.

2)  Why is the inverter positive wire doubled?  If there is such a solution as I've guessed above, how do I deal with that?

I do have a fuse on the outside of the trailer for those trailer wires.  And I got a fuse panel for all my internal 12 volt stuff. The wires from the charge controller are long enough I believe and if they are not I know how to handle them.

2) I'm also toying with the idea of cutting a hole in the side of the plastic box and putting that computer fan in there and wiring it to my solar panel "load" inputs so that it only runs dawn to dusk (while the batteries are being charged)  Is that necessary?  I'm worried that since I'm trying to make it airtight so that doesn't leak fumes, that will also do away with a lot of the natural ventilation of an rv storage bay.  Or will the ventilation tube be enough for that?

Ok, fire away.  Just please lets go with the assumption that I'm not overly worried about outgassing but more want this to add a measure of orderliness and ease of access to my setup.  On the other hand if you see anything that is absolutely horribly wrong please tell me.

Thanks for the help.

 

[ccbreder]

Not 2 AWG. 2/0 AWG, meaning 00 AWG. I just want to repeat what Sternwake has said above. Take time to read the links he posted, and buy your cables from genuine dealz. Except, Boil the battery is a descriptive term to explain to a beginner the condition in the cells of a heavily charged battery. Everyone has seen boiling water, but not many the rapid churning of battery acid. Except in special occasions, battery acid should not boil. From my Webster's; boil 3 to seethe or churn like a boiling liquid
I have a very small computer fan exhausting my battery box. There is no possible spark where it would matter. Pushing air into the box would cause fumes to exit from any unsealed crack or seam. Not an explosion hazard, but I don't want the fume in some areas. Thermal chimney-ing would move air in from the bottom and out the top. The riser should be without bends and continue straight up as a chimney. PVC would be fine as an vent pipe. separate note, my little fan runs constant and is a very light draw.

 

[DannyB1954]

The reason two vents are better is it is difficult for air to both move in and out at the same time with one vent. Have someone who smokes blow some smoke into a clear bottle and see how fast it comes back out. You really do want the air to flow through to remove fumes. Your battery box will not go into a vacuum trying to push out fumes. For air to get out, it needs to get in.