Ethernet connection with solar panel

Old Forum

posted May 22 '19 at 3:01 pm

Hello again,

I'm working on a project where the client wants an always active Ethernet connection, but without access to AC power. (Different project to the last one).

This is a weather station, which will be logging every five minutes, but I'd like if possible to also have the wind speed sensor do three second rolling gust calculations as shown in the FAQ example.

If this is too power hungry, it may need to be dropped, as I realize it would basically involve the station having no idle time. The plan for the power connection is a solar panel and a 12V lead/acid battery going into a charge controller, which has its output hooked up to the external power input of DT80.

I'd just like some feedback on my calculations for the solar panel/battery requirements. From the manual and other examples, I estimate this system should have at most a 1.5 W demand (there's a 12V output attached for a 4-20 mA barometer).

Does that sound right? If so, I figure an 18 Ah battery should have enough capacity. The solar panel may need to be a bit beefier. The climate graph for the region gives me an average of 1.5 hrs/day of sunlight in December (lowest), which if I'm working the solar panel calculations out means I'll need at least a 35W panel, possibly 40W or 50W.

If I'm completely out with my working here, and will need more power than that, I might have to lose the rolling wind-gust calculation, figure out a way to turn off the Ethernet port at night, or both.

Any suggestions, better methods, or other hints gratefully received.

Bruce

Hello again, I'm working on a project where the client wants an always active Ethernet connection, but without access to AC power. (Different project to the last one). This is a weather station, which will be logging every five minutes, but I'd like if possible to also have the wind speed sensor do three second rolling gust calculations as shown in the FAQ example. If this is too power hungry, it may need to be dropped, as I realize it would basically involve the station having no idle time. The plan for the power connection is a solar panel and a 12V lead/acid battery going into a charge controller, which has its output hooked up to the external power input of DT80. I'd just like some feedback on my calculations for the solar panel/battery requirements. From the manual and other examples, I estimate this system should have at most a 1.5 W demand (there's a 12V output attached for a 4-20 mA barometer). Does that sound right? If so, I figure an 18 Ah battery should have enough capacity. The solar panel may need to be a bit beefier. The climate graph for the region gives me an average of 1.5 hrs/day of sunlight in December (lowest), which if I'm working the solar panel calculations out means I'll need at least a 35W panel, possibly 40W or 50W. If I'm completely out with my working here, and will need more power than that, I might have to lose the rolling wind-gust calculation, figure out a way to turn off the Ethernet port at night, or both. Any suggestions, better methods, or other hints gratefully received. Bruce

Roger

posted May 22 '19 at 3:02 pm

Good morning Bruce,

It just so happens I have just finished putting together a presentation on just this topic. A few tips and pointers:

With an Ethernet connection DT80 will not be able to use low power mode. For an Ethernet connection to work the logger must be awake at all times.
Determine the power usage of all devices. If possible use device that run on the same Voltage. If you have some devices that run on 12 v and others at 24V then DO NOT center tap the batteries for the 12 V supply. Center tapping will unbalance the load and damage the batteries, use a Voltage converter to set down the Voltage
Use a solar conditioner to charge the batteries. Batteries will last longer when properly charged. While on the topic of batteries use deep cycle marine batteries and reduce the battery discharge level for the temperature effected.
Determine the number of days the system will run without being recharged. This will allow for cloudy days etc. Typically this will be about 5 days.
Size the solar panels to suit and allow extra to recharge the batteries after days without sun.

Some links you might find useful:

Cheers,
Roger

Good morning Bruce, It just so happens I have just finished putting together a presentation on just this topic. A few tips and pointers: 1. With an Ethernet connection DT80 will not be able to use low power mode. For an Ethernet connection to work the logger must be awake at all times. 2. Determine the power usage of all devices. If possible use device that run on the same Voltage. If you have some devices that run on 12 v and others at 24V then DO NOT center tap the batteries for the 12 V supply. Center tapping will unbalance the load and damage the batteries, use a Voltage converter to set down the Voltage 3. Use a solar conditioner to charge the batteries. Batteries will last longer when properly charged. While on the topic of batteries use deep cycle marine batteries and reduce the battery discharge level for the temperature effected. 4. Determine the number of days the system will run without being recharged. This will allow for cloudy days etc. Typically this will be about 5 days. 5. Size the solar panels to suit and allow extra to recharge the batteries after days without sun. Some links you might find useful: - http://www.solarnavigator.net/lead_acid_batteries.htm - http://www.solarcraft.net/ - http://www.freesunpower.com/ - http://www.motorhomesaustralia.net/solar.html Cheers, Roger

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