[RE-wrenches] Battery based hydrogen incidents

Wed Dec 15 11:35:14 PST 2010

I was hesitant to reply because I surely will look foolish, but perhaps it may help someone in the future. I did something very stupid back in 2001 that caused an explosion. 

The battery bank (12 volt, 660AH) was located in a metal cargo container next to the wall and set in a plastic container. The container had open doors on both ends. The battery was in the absorption cycle with heavy gassing. I noticed that the positive terminal was slightly loose. Fully aware of the danger of the task I was performing, I grabbed my socket wrench and began to carefully snug it down. Even though I carefully observed the location of the wrench, I did not think about the steel container wall as having a path back to battery negative. It did. I blew the top off a battery that I was standing over. Fortunately I was wearing safety glasses or I probably would not be here today typing this. There was a water hydrant near and I was able to flood my face and body for about 15 minutes. No facial scares but a lessen very well learned: Do NOT work on batteries that are off gassing. Gassing begins at about 2.3 volts per cell. If you are a battery novice, I encourage you to thoroughly educate yourself and do not neglect your safety gear when working on batteries.

Another event I witnessed: In 2007 I was at a campground and heard an explosion. The owner of an RV a few spaces down from me was opening the battery compartment as I walked up. Inside he had  un-vented batteries in the same compartment as the inverter and other switch gear. His batteries were obviously gassing when something sparked it off. The top was blown off a 6 volt battery and he had electrolyte everywhere and a damaged cargo door. We work on hundreds of RV's and sadly I see this kind of poor "workmanship" every week at our service center.

Larry Crutcher
Starlight Solar Power Systems
928-342-9103
  ----- Original Message ----- 
  From: Kent Osterberg 
  To: RE-wrenches 
  Sent: Wednesday, December 15, 2010 10:21 AM
  Subject: Re: [RE-wrenches] Battery based hydrogen incidents

  Sounds like, in general, that the off-grid industry has been fortunate to not have hydrogen explosions.  That's good.  No explosions here either.  But one shouldn't take that as evidence that it couldn't happen.  I don't believe this is a circumstance where it is better to be lucky than good.  That's why I recommend doing the calculations.

  Kent Osterberg
  Blue Mountain Solar

  Dana wrote: 
    Ken - 

    To meet the flow have run 2 and 3 fans to meet the flow. 2" output from the fan into a 4" header with a matching 2.5" inlet as far away on the lowest portion of the battery box.

    In 22+ years in off grid installations I have yet to see or even hear of one hydrogen explosion. I get repeatedly asked why we have to go to the efforts we go to for box and venting. I am not able to provide even one incident that I have heard rumor of.

    Q - How many battery based hydrogen incidents have happened in our collective experience?

    Dana Orzel

    Great Solar Works, Inc

    E - dana at solarwork.com

    V - 970.626.5253

    F - 970.626.4140

    C - 970.209.4076

    web - www.solarwork.com

    "Responsible Technologies for Responsible People since 1988"

    Do not ever belive anything, but seriously trust through action.

    From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Kent Osterberg
    Sent: Tuesday, December 14, 2010 12:07 PM
    To: Wrenches
    Subject: [RE-wrenches] Battery Venting

    Fellow Wrenches,

    The discussion about battery venting reminds me of a useful and inexpensive program, BattMV, for determining ventilation requirements per EN-50272.  EN-50272 is a European standard used to determine how much air flow is needed for a room, I don't know of a equivalent standard used in the U.S.  It takes a surprising amount of ventilation.  For a 400-AH 48-volt L16 bank charged at 57.6 volts and 24 amps, it's about 7 CFM just to keep the %H2 down to 4%.  A 12-volt Zephyr vent is good for about 5 CFM!   If you think you are venting enough, take some time and study this issue.

    Kent Osterberg
    Blue Mountain Solar

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