Hello, I have a question about the Arduino's current usage. I want to play around with some sleep modes to save power from a Li-ion, single cell battery. Before I go sticking multimeter leads in places that I should not, where is the best place to measure current in the Arduino when connected USB? I haven't connected the battery yet, and currently my friend has it on him. A simple 'red lead to +5V and the other to pin so and so' would be good enough for me. Thanks in advance for checking this.
bullroarer:
Hello, I have a question about the Arduino's current usage. I want to play around with some sleep modes to save power from a Li-ion, single cell battery. Before I go sticking multimeter leads in places that I should not, where is the best place to measure current in the Arduino when connected USB? I haven't connected the battery yet, and currently my friend has it on him. A simple 'red lead to +5V and the other to pin so and so' would be good enough for me. Thanks in advance for checking this.
You can't really do it when it's connected to USB. The current measuring device has to go in series with the power supply.
https://learn.sparkfun.com/tutorials/how-to-use-a-multimeter/measuring-current
You can't really do it when it's connected to USB
Connected a 9V battery and got ~48mA. Found that to be normal after a little research. Now I want to put it into sleep mode and measure the current. will I connect my multimeter leads the same way?
Measuring current draw from a USB port on a PC can be a little problmatic from a practical side. That's why I jumped on the below cute little item a few months ago when I came across it. Seems to work ok but not the most rugged thing I've come across. Alternates display from volts to milliamps and I haven't verified it's accuracy yet, but at the price I couldn't resist.
http://www.ebay.com/itm/390646012397?_trksid=p2059210.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
The range is nice for how little it is. I can already see where my problem is going to be. I've calculated all my power while connected to the USB port. I'm using a solar panel with a 3.7 li-ion battery. There's going to small differences that will have some effect on the output power, but I doubt it will that big of a deal.
Kudos to the find! Looks to be something a USB stick would like to have by its side.
I think the regular arduino board uses a linear regulator, which wastes the extra voltage so maybe sleeping with a switching regulator is a better choice?
bullroarer:
You can't really do it when it's connected to USB
Connected a 9V battery and got ~48mA. Found that to be normal after a little research. Now I want to put it into sleep mode and measure the current. will I connect my multimeter leads the same way?
Yes.
liudr:
maybe sleeping with a switching regulator is a better choice?
That looks like it would do the trick, I'll keep that in mind when I print a new board for the Arduino.