John, One factor that is being missed out on the calculations is how good is the battery in question. Most assume that say a 7Ah capacity battery will give that, but in practice this can often fall short. I've witnessed experienced installation contractors with skills of loading in the last mAh into large communication battery plant, sweating to get over the 90% mark to the defined pass figure for acceptance. They use techniques probably not used by most hams in order to achieve this and get the acceptance certificates signed off.
So how good is the battery being used today? It may have only 75% of original capacity left, so better to be on the generous side what the duty cycle may be and be pleasantly surprised when the estimated battery life is exceeded. Not too sure if this applies in the USA, but there is a source of 12V 7Ah sealed batteries available from commercial alarm systems in the UK at least. The batteries in these systems are trashed at about 3 years after new battery installation. I guess it must be a lot more cost effective for the maintenance companies to do this rather than experience costly failures. We have a few recycled batteries here providing power backup for local repeaters. It pays dividends to get to know who your local alarm technicians are to tap this source of batteries for field operations. Should get at least two or three years more life out of these batteries depending on temperatures experienced during their usage as high temperatures dramatically shorten their useful life. Bob, G3VVT K2 #4168 _______________________________________________ Elecraft mailing list Post to: [email protected] http://mailman.qth.net/mailman/listinfo/elecraft You must subscribe to post. Subscriber Info (Addr. Change, Unsub etc): http://mailman.qth.net/subscribers.htm Elecraft page: http://www.elecraft.com
