I'm quite new to Arduino, I've done a few small projects and the biggest thing I'll do is automatic watering system for my garden, using Electromagnetic valve:
Now, there is a questions of powering such a system. Given that it will be placed outdoor, the best way would be to use power bank, since batteries does not have needed capacity in my opinion. Valve works od 12 V, so I need a power bank with 12 V output. It would be the best if I can power both Valve and Arduino from the same power bank, so I would need a 2 DB outputs, lets say both 12V.
This has only one output for example:
Is there any kind of splitter I can use, or should I buy the same power bank with 2 12V DC outputs?
I'll link valve over the relay as shown in the image attached (note that on the image valves use 220v powering, while my valve used 12v).
Power bank capacity is 20 000 mAh and valve has drain 250 mAh so the power bank could go up for about a week, which is exactly what I need.
Typical powerbank outputs auto-shutoff if the load is small. The selectable output
voltage on this one may be different as its designed for something other than charging
a phone - so hopefully it will work for this, but be aware of the possible issue.
20Ah over a week is 0.12A only. And that's at the 3.7V of the lithium cells, at 12V it
will be a quarter of that, 30mA or so. You can't boost voltage without reducing current!
Have you considered a 3S LiPo pack? 11V is close enough.
MarkT:
Typical powerbank outputs auto-shutoff if the load is small. The selectable output
voltage on this one may be different as its designed for something other than charging
a phone - so hopefully it will work for this, but be aware of the possible issue.
20Ah over a week is 0.12A only. And that's at the 3.7V of the lithium cells, at 12V it
will be a quarter of that, 30mA or so. You can't boost voltage without reducing current!
Have you considered a 3S LiPo pack? 11V is close enough.
Thanks for the reply. So in that way, if 120mA is maximum for 7 days, a simple calculation says this power bank will be empty after 3-4 days?
I'll check this batteries out, but the issue is they are 11.1V and valve works on 12V.
Can you comment on the possibility that I have lets say power bank with one 12V DC output and then split that on 2 parts - one for Arduino, another for relay? (I mentioned that in original post)
