There is a simple way to have a reliable backup battery system without a relay. Try this:
Connect your fused repeater power cable directly to the battery terminals, without any intervening devices. Connect your power supply to the battery through a single Schottky diode. Adjust the power supply voltage so that the battery is floated at its optimum voltage, to account for the small forward voltage drop across the Schottky diode. I use a Schottky diode because its forward voltage drop under load is much smaller than that of a silicon diode and is stable. The diode is needed because some power supplies have a tendency to go into a "crowbar shutdown" mode if the AC input goes away (as during a power failure) while a DC voltage is maintained at its output by a battery. Such an event will blow fuses and will almost certainly shut down the repeater. Unless the repeater operates almost continuously, the power supply does not need to match the current draw of the radio during transmit. I have a 50 watt base station set up this way that has a 26 Ah VRSLA battery floated by an Astron RS-10 power supply, and it has been 100% reliable through many power outages. I used an International Rectifier #122NQ030R diode, simply because it was easy to mount on a copper bar that is bolted to the positive terminal of the power supply. The "R" in the part number indicates reverse polarity, meaning that the diode terminal screw is the cathode, which is convenient for attaching the load wire. Here's the datasheet: http://www.irf.com/product-info/datasheets/data/122nq030.pdf 73, Eric Lemmon WB6FLY At 09:18 PM 04/18/06, you wrote: >Captainlance <[EMAIL PROTECTED]> wrote: > >What would be the next best charger, if one >doesn’t have a Micor Power Supply with the >battery charger or our Micor Power Supplies don’t have the battery charger ? > >73’s, >Jim Kh6jkg 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/
