I'm looking at setting up some nodes at mountain top locations. Commercial power is available... but I don't want to be totally relying on it. And the site can be a challenge to get to even in the summer, and worse in the winter. If I'm doing my math right, I think a 35Ah battery should be fine for getting me at least 3 days of run time. But the temperatures could get down to around -15 degrees F in the winter and top 100 degrees in the summer, so I'll need a charger that can suitably adapt for that, while knowing how to provide a maintenance charge to maximize battery life.
And a disconnect switch to disconnect the load before the battery voltage drops enough to risk the battery... including freezing. But doesn't itself consume enough power to materially affect run time. And... it would be nice if I could come up with something with negligible power requirements that could notify me of a site power outage. And all of the above without costing more than necessary to get the job done.
Suggestions?
Dave
And a disconnect switch to disconnect the load before the battery voltage drops enough to risk the battery... including freezing. But doesn't itself consume enough power to materially affect run time. And... it would be nice if I could come up with something with negligible power requirements that could notify me of a site power outage. And all of the above without costing more than necessary to get the job done.
Suggestions?
Dave
Random thoughts:
Off the top of my head, something like one of the various arduino flavors with an ethernet "shield" might be able to do most of the management. It could measure battery voltage, cell output, temperature, etc. and serve up a simple web page as a mesh service. If there's an internet gateway somewhere it could send you an email or text message. It could spend most of the time asleep. A simple power MOSFET could switch power to the nodes off. (No idea why anyone would design a low battery cutoff using a mechanical relay!) I suppose a charge controller could be incorporated as well. In a low battery situation you might want it to give priority to powering the node before trying to charge the battery...