Hello. I'm currently trying to find the battery drain for one of my projects. I want to implement a sleep mode, which will reduce power, but I want to know the difference this implementation makes and see the difference in how long the battery lasts.
I'm really not good with electronics, so I need a bit of help. Below is a schematic for my current design. I have a 3.7V 1000mAh Lipo Battery. I'm using the Adafruit LoRa M0 with a Water-proof Ultrasonic Sensor (Water-proof Ultrasonic Sensor | The Pi Hut).
I do have a multimeter, but I'm more afraid of damaging the circuit as I know nothing about this kind of stuff. If anyone has any guidance or advice I'd appreciate it.
Some tips on measuring low, as in sleep, currents here;
I note your using a LoRa device, so for some ideas as to how long a battery will last if your sending sensor data on a regular basis, see here;
Note that using a very low capacity battery, say 100mahr, is a practical and simple way of measuring real world power consumption, there are of course more complex ways ......
BE CAREFUL. Most multimeters require you to move one of the test leads to another input on the meter if you want to measure current. IF YOU LEAVE THE LEADS IN THE CURRENT MEASUREMENT INPUT BUT PUT THE SELECTOR ON VOLTS, THE LEADS WILL SHORT OUT WHAT EVER YOU CONNECT THEM THROUGH.
You must move the lead back to the voltage input before trying to measure voltage.
If this is not clear please post a photo of your multimeter and we can guide you better.
I do it a little different. I use a Schottky diode (low leakage) in series with the battery and shunt it with a resistor. The value of the resistor is determined by what current I want to measure. The diode keeps the system going if it comes alive or has a current surge it limits the voltage drop across the sense resistor. I then connect my meter across the resistor to make the current measurement. Unless you have the exact resistance you need to use Ohm's law to calculate the current. This is available on line at: Ohms Law Calculator. This allows me to make low current measurements without worry about blowing my meter yet still having enough power to supply the load. The nice part is if the load cycles I do not have to change anything in my setup. Just a note I use a lab power supply instead of a battery and adjust for the resistor but in this case the error will be negligible. For more accuracy measure the resistor value.
Unfortunately I don't know how the low current measurement works on your multimeter. Your multimeter (and it seems a lot of the new multimeters) seems to use the "voltage" inputs for low current measurements. I've not used one of these so I'll let others with more info on this type of current input take over.
These meters normally use the voltage inputs ( right input and centre common ) for low current measurement, up to 200 mA. There is a fuse in the circuit.
I would recommend starting measuring current using the left hand input (10 ADC) and centre (common) and if the reading is below 200 mA switching to the other ( right hand input) when you will not blow the fuse.
G
it's the two channels. One of the channels (the one he is on) is rated for 100mA 1000V max (typical, and is FUSED)
The other one is rated 10A 250V (max duration 10 second) UNFUSED (or fused) and can only do current.
You can get a better understanding of what the different prongs are if you look at the brackets and the labels.
Most analog and cheap digital ones have the "three lead" design where you need to mechanically move it from one prong to another (complicate operation to reduce chance of human error). Some even have four leads. I have one that does that. but I also have two bench DMM that you can choose between ranges with a simple button press (and two different fuses inside), and they come with onlg two prongs to start with.
In the case of Arduino, both channel is completely fine and the 100mA 1000V channel will yield more accurate results. Unless it did used more than 100mA, but in that case the meter will probably just read "1"(overrange) and he would have figured long before he melt the fuse.
