Instead of talking 33.3 days and 24 hours of sun, let's just take an average day.
At optimal output, and for the sake of argument, let's say our 60W rated panels only produce 45W; optimally. Let's lob off 12% of that to satisfy the naysayers and devil's advocates, and to account for inefficiencies. We have a power output of close enough to 40W. Not all can do it, but for the short run repeater, and with two radios, let's say we run it at 12V, while loosing less heat at the voltage regulator on the radio. Since we're rounding numbers, we'll call that 3.3A. The radios require .8A. During optimal conditions, there are 2.5A free to charge the battery. On our average day, we have 6 hours of optimal sun, maybe more, maybe less. We have gained 15AH of charge to send to our battery. For 3 more hours of the day we will receive less than optimal output -- 2.5A, for another gain of 5.1AH. We now have 20.1AH more than we need to run the radios. We will get another hour of diminished 1A or less output but will not consider that here. So, during our 24 hours, we are either generating enough, or excess for 9 hours. We have to store power for the 15 hours where our system is not generating power. We have to provide 12AH for dark time. We have already generated an excess of 20.1AH. We can provide 8.11AH on our average day to keep our battery charged. If the 12V storage battery is capable of 800AH, and it is topped off with our system it CAN keep the repeater going for 41 days. If you monitor battery condition, you should be able to see a net loss coming way before it shuts down the repeater. Assumptions: We are using efficient radios capable of running at 12V or less. Let's say both are Atheros based Deliberant radios. The CAT5 run to our radios is insignificant, and not some 200' run. Hams, geeks and wisp owners are cut from similar cloth. Mike -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
