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 - d...@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-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@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 <http://pocketengineer.design.officelive.com/battery_ventila tion.aspx> , 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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