Kevin, I suspect that you have lead-acid wet cells, which emit corrosive vapors and hydrogen gas when charging. Be very careful to enclose these cells in containers that are vented to the outside air. Normally, one would use sealed, nonspillable cells for such duty.
Your rough calculations are correct. If the repeater were online continuously, the current draw times the hours would suggest a long backup capability. However, you must consider whether the end voltage upon which the battery capacity is based, is the same or higher than the voltage at which the repeater shuts down. Repeaters are normally not continuously on line, so the batteries will last longer than the calculations. However, during a power outage, repeaters often get more use than during normal times, so this must be considered. I prefer a "belt and suspenders" approach. I have a primary repeater that is far from commercial power lines, and it has been on a solar power system for more than three years. The storage system is two, 205 AH sealed lead-acid batteries in parallel. Although the system has never failed, I am adding a wind generator to ensure reliability if there are several consecutive days of very foggy weather. The bottom line here is that you should base your backup requirements on realistic current draws, but then "hedge your bets" with a generous excess. Remember that Mother Nature enjoys testing your system with extended periods of very unusual weather! 73, Eric Lemmon WB6FLY -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Kevin & Natalia Sent: Sunday, February 12, 2006 10:08 PM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Battery Back-up Question G'Day All, I am about to install a set of back-up batteries for our repeater. Designed for back-up use. These are 2volt cells, 460amp/hr over 10hrs. What is written on them So we have 6 cells connected together to give 12volts. We are pulling , when everything is running, no more then 10amps. As a rough caculation, I am guessing the batteries should last for around 400+ hours. Anyone got a full caculation to find out how long they will last? Regards Kevin. Yahoo! Groups Links Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
