(Continued from Part 2.)
Photovoltaic (PV) Power
Power can be supplied by an internal or external source. For long-term fixed installation, a single wire pair can deliver power from a 12 to 24 vdc from a PV panel to a battery stored inside, or placed outside, or directly to the voltage step-down converter inside. A Baofeng battery eliminator can accept the higher voltage of a PV panel and step it down to 7.4 volts that the transceiver requires. However, there is no battery present to be charged and consumed after sunset, whereas with the voltage step down covert charges the transceiver’s battery. This is the most efficient use of PV power.
Anytime electrical power is converted into a chemical form and then reverted back to electrons (on discharge), there is power lost in the conversion, approximately 15% by some estimates. Bypassing a storage battery and a charge controller, and the usually long runs of DC wire that can represent an additional 5&% loss, improves the efficiency of a small PV system, greatly. And an expensive MPPT charge controller that can improve efficiency during cloudy periods is not needed. The step-down voltage converter is a homemade item, and is detailed in ny SurvivalBlog article Commo for Family, Group, and Community, Part 5. This allows one to use either solar direct power or battery operation, or both.
For the more sunny six months of the year, when no storage battery is used, 10 watts of PV power is a minimum for each one handheld transceiver that needs to be in operation 24/7,and when, and where one transceiver is turn on and receiving, while a second transceiver is off and charging from the same power source. As a minimum, 10 watts is needed for northern latitudes, because the crossband repeater has two transceivers that are turned on 24/7. Ideally, they should both be outfitted with the large 3800Mah batteries that will supply power during overcast days when the PV panel output drops to 10 to 20% of full production.Continue reading“A Low Power Communications Station in a Bucket – Part 3, by Tunnel Rabbit”