Hi Ian, I look after a number of solar powered, mountain-top repeater sites.
Reduce the number of points of failure. Use panels in your array with the same capacity, parallel them together. With most panels this is easily done right on the back with short jumpers. Run the output of the array to a junction box near the array and connect it to a significantly larger gauge wire to run to wherever the equipment is. Regardless, try and keep the run as short as possible to minimize voltage drop. Put in the biggest wire you can afford. Use batteries of same capacity and parallel them together. It is VERY rare that you have a battery fail that takes out the whole plant. Keep it simple. No diodes, switches, etc. Run it all through a suitably rated solar controller. PWM models are the most efficient. Moringstar makes some very well built units. Most models have built in low voltage disconnect (LVD) that you can use, if you choose. They generally disconnect at a fairly low voltage (like 10.5V), and re-close when the battery has re-charged some, and the voltage has started to recover. It all done with FET's... no relays to fail. You can also just put the equipment right across the battery plant (suitably fused), if you want to get the most run-time possible. But with this approach, you do risk damage to the battery plant if you have a deep discharge where your solar plant can't keep up. If you're not using low power radios designed for this application, you're going to probably run into trouble... get all the numbers for current consumption and expected duty cycle, and plug it into one of the many calculators on the internet to get an idea of the size of the battery plant and solar array capacity that you'll need. You'll be surprised how quickly the numbers get big. I will tell you from experience (just tinkering) that a 50W panel, with 400AH of battery plant is not enough to keep even a Motorola Maxtrac alive through the winter on an APRS digi in a moderate coastal climate. Our mountain-top sites are generally two 4W TX (UHF and VHF) and two RX (UHF and VHF), its a VHF repeater with a UHF backhaul. The transmitters typically draw about 2A each when transmitting. The receivers around 100mA each. When not transmitting, the TX power right down, and the current consumption of the RX drop to about 80mA each. The solar plant is typically 100W+ (depends on duty cycle), and the battery plant is generally in excess of 1500AH (again, depends on duty cycle and number of days of designed autonomy). Run the numbers, and figure out what you're going to need to make it all work. There are a number of good sites on the internet for figuring out the average hours of sunlight for a particular location, as well as proper angles to set the panels at, depending on latitude. Check them out. Cheers! Lee --- In [email protected], "Kerincom" <[EMAIL PROTECTED]> wrote: > > Two 80 watt panels parallel supplying the two regulators which then charge > the 2 batteries separately .The idea I am working with is not to use the two > batteries in parallel in case one goes flat and takes the second out but to > either with the first part to reduce the current draw on > The batteries by separating the TX and rx power sources or to have a main > and backup battery incase the main goes flat > Thank You, > Ian Wells, > Kerinvale Comaudio, > 361 Camboon Road.Biloela.4715 > Phone 0749922574 or 0409159932 > www.kerinvalecomaudio.com.au > > -------Original Message------- > > From: skipp025 > Date: 2/08/2008 12:18:39 AM > To: [email protected] > Subject: [Repeater-Builder] Re: Dual battery system > > Hi Ian, > > The first questions I would want to ask you are ... > > Are you supplying the charging energy to each charge controller > from the same or different solar arrays? > > Why the two solar chargers versus one solar charger? Is your > array made of mixed type/capacity panels? > > skipp > > > "Kerincom" <kerincom@> wrote: > > > > Hi guys .I am wondering if anyone knows of good pages on dual batteries > > systems and comments on which of following questions is better > > > > I am wondering if having two batteries .one for the receiver and one > for the > > TX each with its own solar regulator or > > A system where two batteries are charged by two separate regulators > and the > > TX and rx run off one battery and when extended no solar period > happens the > > repeater is switched to the second battery when the main drains > below 10 or > > 11v and returned to the main when it charges back up > > > > Thank You, > > Ian Wells, > > Kerinvale Comaudio, > > 361 Camboon Road.Biloela.4715 > > Phone 0749922574 or 0409159932 > > www.kerinvalecomaudio.com.au > > >
