Some really good lessons here, thanks Larry I forgot to mention one of my explosions, I was checking connections and found one loose but I had turned off the battery bank. but there were four parallel strings connected I believe the string I was working on had a small current flowing or some thing because moving the cable to test connection caused expolision.
Inside the battery is hydrogne and oxygen in the perfect ratio, it detonates, with almost any spark, I am sure the flame kernel is much smaller than gasoline in air for example. Darryl --- On Wed, 12/15/10, Starlight Solar, Larry Crutcher <[email protected]> wrote: From: Starlight Solar, Larry Crutcher <[email protected]> Subject: Re: [RE-wrenches] Battery based hydrogen incidents To: "RE-wrenches" <[email protected]> Date: Wednesday, December 15, 2010, 1:35 PM 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: _filtered #yiv774257597 { font-family:Calibri;} _filtered #yiv774257597 { font-family:Tahoma;} _filtered #yiv774257597 { font-family:Century Gothic;} _filtered #yiv774257597 {margin:1.0in 1.0in 1.0in 1.0in;} #yiv774257597 P.yiv774257597MsoNormal { FONT-SIZE:12pt;MARGIN:0in 0in 0pt;COLOR:black;FONT-FAMILY:"serif";} #yiv774257597 LI.yiv774257597MsoNormal { FONT-SIZE:12pt;MARGIN:0in 0in 0pt;COLOR:black;FONT-FAMILY:"serif";} #yiv774257597 DIV.yiv774257597MsoNormal { FONT-SIZE:12pt;MARGIN:0in 0in 0pt;COLOR:black;FONT-FAMILY:"serif";} #yiv774257597 A:link { COLOR:blue;TEXT-DECORATION:underline;} #yiv774257597 SPAN.yiv774257597MsoHyperlink { COLOR:blue;TEXT-DECORATION:underline;} #yiv774257597 A:visited { COLOR:purple;TEXT-DECORATION:underline;} #yiv774257597 SPAN.yiv774257597MsoHyperlinkFollowed { COLOR:purple;TEXT-DECORATION:underline;} #yiv774257597 SPAN.yiv774257597EmailStyle17 { FONT-WEIGHT:normal;COLOR:windowtext;FONT-STYLE:normal;FONT-FAMILY:"sans-serif";TEXT-DECORATION:none;} #yiv774257597 .yiv774257597MsoChpDefault { FONT-SIZE:10pt;} #yiv774257597 DIV.yiv774257597WordSection1 { } 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 - [email protected] 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: [email protected] [mailto:[email protected]] 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 _______________________________________________ List sponsored by Home Power magazine List Address: [email protected] Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org _______________________________________________ List sponsored by Home Power magazine List Address: [email protected] Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org -----Inline Attachment Follows----- _______________________________________________ List sponsored by Home Power magazine List Address: [email protected] Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
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