Navitron Renewable Energy and Sustainability Forum

Energy/Electricity Storage and Use/Grid Connection => Off-Grid, Batteries & Inverters => Topic started by: Eleanor on March 01, 2012, 09:10:13 PM



Title: Ventilating a Battery Enclosure
Post by: Eleanor on March 01, 2012, 09:10:13 PM
The tin shed's getting a bit full so the new babies are going to live outside. The general idea is to build a box out of ply and line the floor with XPS with a sheet of ply on the top to distribute the weight of the cells. The sides and lid would be lined with EPS and XPS if there's any left over. I've also got some polypropylene sheets (same material cells are made from) which I can use to line the inside of the box and protect the insulation from the acid.

I've been looking around for information on how to safely ventilate the box and have found a few sites including the one below which suggest that two pipes near the top of the box is the best way, one of which dips to near the bottom of the box and draws outside air in when hydrogen is vented from the other pipe (Fig 5 in the link) :

http://zomeworks.com/research/hydrogen-venting/basics (http://zomeworks.com/research/hydrogen-venting/basics)

Any thoughts appreciated. Maybe I'll make sure the lid isn't fastened down just in case  sh*tfan:


Title: Re: Ventilating a Battery Enclosure
Post by: camillitech on March 02, 2012, 07:09:00 AM
I wouldn't worry too much about it Eleanor,sounds like you've got it covered. All the battery enclosures that I've on ships have their lids well and truly fastened down with just or two small vents near the top pointing down the way. Each vent is covered with a fine stainless mesh gauze that acts as a 'flash arrestor'. The steel ones have a lead drip try in them to catch any acid spill but the fibre glass ones don't. 

That article (interesting though it is) seems to be making something far more complicated than necessary  for something that will sit in a well ventilated space (the west coast of Scotland)  ::)

Good luck, Paul


Title: Re: Ventilating a Battery Enclosure
Post by: HalcyonRichard on March 02, 2012, 09:10:55 AM
Hi,
    It seems you can get stagnation if the temperatures are different. i.e. warmer outside the battery compartment than inside. But hydrogen is only produced during charging. wouldn't this produce enough heating to avoid stagnation in the battery compartment ? And certainly make the inside warmer than the outside.


Regards Richard


Title: Re: Ventilating a Battery Enclosure
Post by: Eleanor on March 02, 2012, 10:28:29 AM
Thanks both. When I first started looking at it I would probably have put vents at the bottom and top so I learned something about putting them at the same level (and this seems to have been borne out by Paul's ship battery boxes). So just two tubes at the same level, one that goes straight in and another which bends down to near the bottom of the box seems to be the way to go. Both fitted with stainless wire mesh where they exit. I think the information in the link is mainly intended to deal with the opposite to what we have here ie outside warmer than the inside but I suppose it could happen  fpig:
Paul, if I can overcomplicate it, I will ::)


Title: Re: Ventilating a Battery Enclosure
Post by: Eleanor on March 02, 2012, 10:47:10 AM
Maybe I'll lose the tubes ....... I used to be indecisive ..........  surrender:


Title: Re: Ventilating a Battery Enclosure
Post by: Outtasight on March 09, 2012, 11:16:55 PM
How are you going to be able to take photos of the insides of the cells for the manufacturer to argue the toss over next time with these cells tucked up in a coffin like that?   :P

I'll get me coat...


Title: Re: Ventilating a Battery Enclosure
Post by: Eleanor on March 10, 2012, 08:02:22 PM
Unfortunately I'll be the one getting me coat  :winter
It's alright for those who keep their cells behind the sofa  ;D


Title: Re: Ventilating a Battery Enclosure
Post by: jonesy on March 29, 2012, 03:39:28 PM
I once installed an enormous UPS - the type that has a battery room the size of a living room, and can support a large industrial process for an hour.  The (resident) fire officer wasnt even interested in a hydrogen alarm.  His research showed that the hydrogen liberation of lead acid batteries was minimal.  From memory we fitted a  couple of 20x20cm vents.


Title: Re: Ventilating a Battery Enclosure
Post by: Outtasight on April 02, 2012, 01:23:32 PM
Artful, that's true for AGM and gel cells that are used with UPSs but not true of the flooded cells that Eleanor is using, which make LOTS of gas when charging.

But even gel and AGM cells require some level of ventilation.  It's just that the requirements for air changes per hour are so low that normal home / office ventilation is more than enough and data centres usually have much higher rates of air change than that, so it's never an issue. 

The main requirement for ventilation in UPS battery rooms is more concerned with keeping the battery temperatures below 25C to extend their service shelf life.


Title: Re: Ventilating a Battery Enclosure
Post by: Eleanor on April 02, 2012, 02:55:34 PM
Not sure what I'm doing here when my task for the day is putting this lot together. I cheated a bit as one of the local builders has a DIY shop and I gave them a drawing so they could cut the panels. At least it means they are straight  ::)


Title: Re: Ventilating a Battery Enclosure
Post by: jonesy on April 02, 2012, 04:33:08 PM
Quote
Artful, that's true for AGM and gel cells that are used with UPSs but not true of the flooded cells that Eleanor is using, which make LOTS of gas when charging.
I must confess that I didn't know this..  seems the fire officer didnt either, as they were flooded cells  ;D


Title: Re: Ventilating a Battery Enclosure
Post by: Outtasight on April 02, 2012, 05:40:47 PM
Ha hahahaha... You don't live anywhere near the data centre with those batteries I hope.

This is a video I made a couple of years ago when I was running flooded cells at home behind the sofa...

http://v5.tinypic.com/player.swf?file=90rayo&s=5"

I used to have fish tank pipe pushed into the vents on the four 110Ah batteries and piped the gas through a hole in the window frame to the outside.  One day for a laugh, I put a plastic bag over the exhaust and collected this lot.


Title: Re: Ventilating a Battery Enclosure
Post by: jonesy on April 03, 2012, 10:40:01 AM
This may not be the response you expected, but I GOT TO GET SOME FLOODED CELLS AND SOME BIN LINERS. :hysteria

I saw a program on TV the other night when they put about a 1" cube of sodium in a tank of water.  Fantastic.  Reminded me of stealing tiny sodium pieces from school and making hydrogen at home.    :angel:

Probably just as well I've gone from off-grid to on-grid.  The temptation....

And no, I dont live anywhere near it.  It was over 20 years ago, so more than likely been replaced.  Phew.


Title: Re: Ventilating a Battery Enclosure
Post by: stephendv on April 03, 2012, 11:21:43 AM
From TAB battery, ventilation requirements according to EN 50 272-2


Title: Re: Ventilating a Battery Enclosure
Post by: Paulh_Boats on May 03, 2012, 01:47:15 PM
Eleanor,

How are you these days?

The boast safety scheme for inland boats recommends fans in the battery areas to vent gas - obviously brush-less fans that can't generate a spark!

Also if you have a good quality charger gas bubbling will be minimised.

-Paul


Title: Re: Ventilating a Battery Enclosure
Post by: Eleanor on May 04, 2012, 10:56:08 AM
Hi Paul, all is well here, glad that you're still around. I guess you've been busy boating? The enclosure is fairly well ventilated at the moment as it doesn't have the front or top on yet  ::) It's possible to change the absorption voltage settings on the Outback (which does most of the charging) but at the moment it's just set at the standard 2.4V/cell. As we're bubbling air through the cells I think we should be able to reduce this to avoid too much gassing  :crossed


Title: Re: Ventilating a Battery Enclosure
Post by: Paulh_Boats on May 04, 2012, 01:26:31 PM
Eleanor,

Yes boating but also archery as a new hobby - because my youngest daughter has become a very competitive archer.

Slightly off topic but I'm really pleased to see lots of houses with solar panels as I drive around and its amazing how cheap PV panels have become.

I'd like an battery based LED lighting system for the house - there are some excellent LED dimmers on ebay and I've bought one to dim the cabin lights on my boat. Its just a shame batteries don't last forever....yet.

-Paul