How much current can I draw off the 5v connection?

[William]

I have an ESP32 based project I am adding to my Opensprinkler installation. It would be helpful to power it right off the opensprinkler 5v supply. It draws 180mA max. I don’t want to draw too much current off the 5v supply. How much can I safely draw? Here’s my project. It uses AI to enable/disaple the sprinklers.

https://github.com/bill-orange/Sprinkler_Controller

[Ray]

It’s probably ok. The entire 5V rail can supply up to 2 amp. OpenSprinkler’s ESP8266 draws about 100 to 150 mA (if you use wired Ethernet module, that’s another 180mA). So it can easily support another gadget that needs 200mA. Keep in mind that all this power eventually come from the external 24VAC power adapter (if using AC) or 7.5VDC power adapter (if using DC), so if you also want to run many zones simultaneously then it’s going to strain the external power adapter. But if you don’t run more than 1 or 2 zones at the same time, it should be ok.

[William]

Thanks Ray. I just looked at the schematic and I should be able to hook my ESP32 GPIO directly SN2. That really simplifies things, no opto-isolator board.

Over the last few weeks, I have been trying to integrate the OpenIA API with my microcontroller projects. In this project, OpenAI will evaluate the data from OpenWeatherMap and decide if the sprinklers should run. As yet, I have not done enough bench testing to tell if it is worth the bother. One day, it did decide watering was not necessarey based on the temperature being too cold for the grass to absorb water. Promising. Here’s the prompt I am using:

“Here are JSON responses from OpenWeatherMap containing current weather and forecast weather.
Please determine if I should activate my lawn sprinklers.
– Use rainfall amounts, precipitation probability, humidity, wind speed.
– Follow these rules:
– If forecast rain (>2mm in the next few days) is likely, do not water.
– If other conditions, such as high winds are present or likely. do not water.
– Otherwise, allow watering.
– If you see the word Rain in either JSON string, do not water. Be sure to read all of the JSON strings.
– Consider morning temperature. If it is too cold in the morning, the grass is likely dormant and will not absorb water.
Respond only with “YES” to inhibit the lawn sprinklers and not water or “NO” to activate sprinklers and water. Do not add any discussion to this structured reply.”

I will repost to this thread if this approach bears fruit.

[Author]

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