At 07:25 AM 10/22/08, you wrote: >Scott, > You are of course correct about hooking the PA directly to the battery, >there being no reason to disconnect it. > > There are undoubtedly many good reasons to consider a more sophisticated >disconnect method than the simple relay circuit described when the ulimate >in power saving is needed. However, I wonder what percentage of the folks on >this list have the technical acumen to design a circuit like this, let alone >trying to gather all the parts for it.
Just buy a LVD module (or a solar charge controller module that has LVD built in). Or build the one from the link that was posted. Or dig through the QST back issues. They had an article on one and a parts kit was available. > The cutout circuit of the solar charge controller you mention does look >interesting and the kit for $55 might easily be adaptable to be used in a >repeater disconnect application. No "might easily be adaptable" about it. Just hook the Astron to the solar panel input, the repeater system (less PA deck) to the load terminals and the battery to the battery terminals. Adjust the Astron to the proper float voltage to minimize the heat generation in the charge controller section.. > However, I still feel that the extremely simple relay circuit I >described will do the job as it has for me in several applications for many >years. With only three or four parts there is very little to fail. When the >box it up on the hill I don't want to have to run up there every time there >is a nearby lightning strike. Most of the solar equipment that I've seen has been designed for that situation. Sunny states like Texas and Florida that get lots of lightning also have lots of solar installations and the solar equipment manufacturers wouldn't be in business if they didn't offer a product that would stand up to a distant strike. . And you can monitor the status of the unit remotely so if it glitches you know it. There are points in the circuit you can tap and feed to digital inputs on the repeater controller. For example, the courtesy beep can change from a simple beep to a morse "B" when you are on battery. > The 100 ma. figure is typical of some of the Rat Shack relays. There are >many that pull much less current available. But can they handle 10a of DC current? I've seen relays that will handle 10a of AC but only 2a of DC, others that are rated at 10a AC or DC. I've found that, in general, the higher the DC contact current the larger the coil. People have opinions, and I respect yours. Simple and elegant is good, but it has to meet the requirements. And minimizing the 24x7 energy drain from the battery when the power is off is primary. My opinion is that once the AC power is off I'd rather NOT waste the available battery charge feeding as much energy to the LVD relay coil as I do the receiver and the controller combined (or depending on the relay coil, as much as twice that). Power outages can last minutes or they can last weeks. Or, as some areas of Louisiana learned after Katrina, months. >Al, K9SI Mike WA6ILQ
