Kevin, I will assume that your solar panels, charge controller, and battery bank are sufficiently robust to handle the entire repeater load, including the accessories. The solar charge controller is a critical part of any solar panel installation, and it is important to ensure that it has complete control over battery charging. In other words, there should not be another source of charging current that flows into the battery. lest the charge controller lose track of the state of charge. Perhaps you can describe how you are regulating the charging of the batteries at this time.
I suggest using Schottky diodes to isolate both the solar system and the mains power supply from the repeater load. The mains power supply output voltage may need to be adjusted slightly to compensate for the small (about 0.4 VDC) forward voltage drop of the diode. The problem with using relays to control power is that they consume power when energized, and that can be a significant load on a heavy-duty relay. You might look into using a solid-state relay based on a thyristor, which will probably have a TTL control input. >From your description of the symptoms, it sounds like the battery voltage is varying enough between solar and mains sources, that it causes the controller to chase it in slow motion- a sort of relaxation oscillator effect. It may also be true that the battery voltage is dropping below the trip point when the repeater is transmitting, possibly because the battery is not sufficiently charged. Some power supplies are unable to start up with a load connected, and that characteristic may complicate your switchover scheme. 73, Eric Lemmon WB6FLY -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] On Behalf Of Gmail - Kevin, Natalia, Stacey & Rochelle Sent: Sunday, July 13, 2008 2:19 PM To: [email protected] Subject: [Repeater-Builder] Need a Switching Circuit for AC/Battery Power Hi, I have a need for switching AC and Battery power at our repeater site. Current setup is mains 230v AC and 12v Battery charging via solar cells. Due to the increasing charges for mains (and still going up) we want to utilise battery power more and use the mains for back-up and when the batteries drop below 11v. The mains is connected to a power supply at 13.8v, this is in parallel with the batteries. I had built a small switching circuit with 2x relays. One relay has the AC inline so the mains power supply can be turned off by the controller remotely or by the scheduler. The second relay was triggered by the AC line so that if the mains went off it would tell the controller which would then switch the repeater to low power mode, timers etc. The problem with the way I had set it up was that when the mains was switched off, even with a solid 12+v on the battery the relay would click continusally because the controller for some reason would see a low voltage and switch the mains relay back on. When the volts was back up to the 13.8v the mains relay would switch off again, back to battery power. I may be pulling straws here in what is actually happening. I have tried to remedy the problem, and had it working for awhile, but it then started doing it again. I would like some suggestions on what way to go? Should mention I am using a RLC-3 controlling the repeater and power requirements. Thanks Kevin
