battery box vent

[defed]

i've been doing a bit of reading on venting a battery box and have found several recommendations for a "convection vent".

i have seen 2 ways to accomplish this.

one as shown here:  http://zomeworks.com/products/h2vent-hydrogen-venting/example-5

the other here:  http://www.bdbatteries.com/hydrogenventing.php

they are basically the same thing except one only needs one hole.  has anyone used this method, in either version?  just wondering if one has any advantages over the other, besides one less hole.

[SparWeb]

They do look similar - the one with the tube-inside-a-tube is a bit of a mystery.  If they are justifying the recommended way to vent the box by referring to the "chimney effect", then I wonder if that concentric design will defeat the effect they seek to harness.  They refer to heat exchange between the two tubes in the second link, but I don't believe you want that if you want thermal differences to move the air.  Sorry - don't know enough about the subject to really weigh in.

The answer probably depends on the situation your battery box is in.  If it's outside, then the external conditions change a lot during the day.  If in a shed, the daily fluctuations aren't as drastic, and obviously if they are in your heated house then the temperature doesn't change much at all.  So you might get away with a vent system that is vulnerable to poor flow on a "cold day", if it's installed inside the house.

Trapping gases under the lid wouldn't be as much of a problem if the lid or ceiling of the enclosure is sloped.  Then you have a definite high spot, and flow out of there will discharge all gases from the immediate vicinity.  That's how mine works.  There is a 2" hole in the wall as high up on the high side as I can go, and I don't worry about an inlet port because the box is nowhere near airtight! 

[defed]

i went w/ a side by side pipe.  inlet w/ a dip tube to the bottom of the box and the outlet just entering the box.  i debated sloping the top slightly to make the vent area the highest point, but i figure if the tube is at the top, and the top fills up with gas, it would go out the tube anyway.

the way i understand the tube in tube design....the heat exchange is when the cold air comes in, it warms from going thru the warm tubes, so as to not lower the inside temp of the box.  i decided not to bother with this, as a 2' length of pipe probably won't transfer heat to the air fast enough.  unless there was a real heat exchanger, or the air moved reaaaaally slowly.

wonder if there is an inexpensive hydrogen gas meter i could stick in there to see if it's working or not.

[fabricator]

[defed]

one that will tell me in a NON DESTRUCTIVE fashion!!!   

[ghurd]

Safety matches?

[TomW]

Safety matches?

G;

Oh, Duh? light match if the atmosphere ignites in the box it means hydrogen buildup

Or not.

Tom

[wpowokal]

Hoe do you know if it is Hydrogen burning? What color is a hydrogen flame?

allan

[fabricator]

Who you callin a hoe?....................

[TomW]

Who you callin a hoe?....................

I distinctly heard "rototiller"

 /
 
 

T

[ghurd]

Hoe do you know if it is Hydrogen burning? What color is a hydrogen flame?

Matches burn with a yellow flame...
Hydrogen burns with a sonic boom.

Doesn't most gassing happen during equalization?
If I was really worried about it, I would maybe connect a tiny (1.25x1.25"?) Brushless muffin fan to a voltage controlled switch.
RCpilot did it with one of my kits.  1st link is the talk about what and why, next is the finished project.
http://fieldlines.com/board/index.php/topic,129163.0.html
http://fieldlines.com/board/index.php/topic,129186.0.html

G-

[freejuice]

Who you callin a hoe?....................

I distinctly heard "rototiller"

 /
 
 
  Tom, I could have sworn I heard ho-down and nobody was shot! It must be square-dancing he speaking about...this is confusing...groan!

 Fabricator has an evil streak by playing with matches around hydrogen ...come to think about it, he is a fabricator afterall and I'm sure he's played with those actylene bottles and plastic bags.  

[fabricator]

I have no idea what you'r talking about................................

[SparWeb]

Then ask the neighbours whose horses are scared out of their skin of plastic bags now!

[fabricator]

LOL, caught red handed.

[freejuice]

I once saw a 30 gallon lawn and leaf bag purged with the right ratio. When it" popped" the concussion at 50 feet was....well, interesting.

[fabricator]

I have been.........told, it's an easy way to catch a bunch of fish in a hurry, you simply tie a balloon to a brick with a piece of water proof cannon fuse duct taped to it and toss it in a likely honey hole, then scoop up dinner.