First of all, I start by explaining how my project will work. I want to set some Arduino Uno borads (equiped with IR and ulrtasonic sensors) that should send the number of cars counted every minute (with Zigbee) to a server (for data processing).
The probem is sending data every minute will rapidly decrease the bettery level, so i thougt to use solar cells as we have a lot of sun here in my country. Other thing I've thinked about it is to programe the Arduino board to not send any data when the traffic is stoped or the number of cars counted is not significant and put it in a sleep mode when the road traffic is reduiced (e.g. by night).
My qustions are :
How much minimum energy do the Arduino need to work corectly (in my case) ?
What kind of battery should I use and how much power ?
What are the dimessions of the solar cells that I should use to get the energy that the board need. ? (I live in a very hot country, so the sun is not a problem).
If it's possible (approximative values will be good), give me the energy consumption of the arduino operations (sending data, converting signals, processing, ...).
If you have any advices or suggegtion, they will be verry helpful.
The energy requirements of the Arduino are quite variable based on what you are doing. If you are doing a lot of analog reads and doing constant computations it may take a lot more power than if you are occasionally doing something and then placing the chip in a low-power sleep mode.
Odds are the larger power draws will be from your sensors and particularly the wireless radio. The draw of these will be entirely dependent on the type and brand of sensor and how you are using it.
If it were me, I would build the device and use a bench-top power supply or a meter to measure the current consumption. Then you can go about sizing your battery and solar panel.
As far as the battery you might look for a sealed lead acid (SLA) battery, as they are meant to be quite hassle free and you can usually find solar panels and chargers that go along with them easily. As far as solar panel area, that will depend on the technology used in the panel, so instead look for one that has the needed wattage. If the panel won't tell you the wattage, you don't want it.
I agree 100% about the use of a lead-acid battery.
Get solar panels that can deliver perhaps twice as much energy during winter daylight as the Arduino needs over a full 24 hrs.
You can probably use the Arduino to turn off some sensors to save energy when they are not needed.
Building a breadboard Arduino would avoid the energy drain of the unnecessary parts of an Arduino board. The Atmel datasheets for the relevant MCU (eg Atmega328) give a lot of data about the chip's energy consumption. One of the very small Arduino boards might be a simpler alternative.
If you want to detect a car even if one arrives unexpectedly you may not be able to put the Arduino to sleep.
list all your devices and power consumption.
arduino itself
IR sensors
ultrasonic sensor
zigbee
I did not read the other thread, but you are are fin with missing counts, then why do you need fast updates ?
once every 10 or 15 minutes.
count 100 cars, then update. that could be very often in rush hour during the day, an very long periods at night.
data log and send time stamped data ?
how much of a problem is lost data ? if you ran your installation for fast updates at rush hour then 15 minutes at night, or longer, you could reduce the power requirements.
jroorda:
If it were me, I would build the device and use a bench-top power supply or a meter to measure the current consumption. Then you can go about sizing your battery and solar panel.
Yes I agree with you the best way for knowing the real power consumption is to measure it , but the problem I haven't the proper instruments and I'm not expert in this domain. I'm just a programmer working on new algorithm for detecting road traffic congetion (my Master's thesis project).
jroorda:
As far as the battery you might look for a sealed lead acid (SLA) battery, as they are meant to be quite hassle free and you can usually find solar panels and chargers that go along with them easily. As far as solar panel area, that will depend on the technology used in the panel, so instead look for one that has the needed wattage. If the panel won't tell you the wattage, you don't want it.
Thank you a lot for these valuable informations. To be honest I didn't heard about SLA batteries before. I will read about them. And thank you again.
Robin2:
Building a breadboard Arduino would avoid the energy drain of the unnecessary parts of an Arduino board. The Atmel datasheets for the relevant MCU (eg Atmega328) give a lot of data about the chip's energy consumption. One of the very small Arduino boards might be a simpler alternative.
Thank you a lot for the information.
"Note that these techniques only work with the Arduino Duemilanove" (from the tutorial page).
Robin2:
If you want to detect a car even if one arrives unexpectedly you may not be able to put the Arduino to sleep.
Why ? Cauz I'm planning to use the time to do that. For exemple at 8pm the Arduino will automatically turn to sleep mode and wake up on 8am. Even if I do this the board can be woked up by a passing car ?
dave-in-nj:
I did not read the other thread, but you are are fin with missing counts, then why do you need fast updates ?
once every 10 or 15 minutes.
Fisrt of all, thank you for answering me.
Yes I was thinking to change the scenario, 1 minute is tooo much for a sensor. The problem is, if I choose a long time the system will loose a lot of information and he will not able to deliver real time road traffic data to users (using an Android application) so I'm on dilemma. What you suggest to me ?
thank you in advance.
At least in the US they chain the traffic counters to the telephone poles and build them in boxes that make them look very industrial and hardly worth stealing.
You should be able to measure the current consumption of your system with just a multimeter and the wall adapter power supply. If you get a separate barrel jack like this one DC Barrel Jack Adapter - Breadboard Compatible - PRT-10811 - SparkFun Electronics you can then wire the power to the Arduino by bringing ground to the ground pin and the V+ to the Vin pin. You can then place your meter in current mode in line with one of those two wires and you have the current.
If you don't have a multimeter yet, now is the time to get one. I couldn't imagine doing a little project let alone a master's thesis without one. Even a $20.00 hardware store meter would give you the information you need and help you out in many other ways as well.
jroorda:
At least in the US they chain the traffic counters to the telephone poles and build them in boxes that make them look very industrial and hardly worth stealing.
That's what I'm planning to do. thank you.
jroorda:
You should be able to measure the current consumption of your system with just a multimeter and the wall adapter power supply. If you get a separate barrel jack like this one DC Barrel Jack Adapter - Breadboard Compatible - PRT-10811 - SparkFun Electronics you can then wire the power to the Arduino by bringing ground to the ground pin and the V+ to the Vin pin. You can then place your meter in current mode in line with one of those two wires and you have the current.
Thanks again for your help. your informations were very informative for a newbie in electonics like me.
jroorda:
If you don't have a multimeter yet, now is the time to get one. I couldn't imagine doing a little project let alone a master's thesis without one. Even a $20.00 hardware store meter would give you the information you need and help you out in many other ways as well.
Yes you're totally right. The problem is, I'm a computer scientist and I'm not good in electronics that's why I'm asking all these noob questions :- ) As now you told that I should have one, I'm gonna buy one.
At least in the US they chain the traffic counters to the telephone poles and build them in boxes that make them look very industrial and hardly worth stealing.
Here too. (I'm a traffic engineer by original profession....) Scrap metal's big business here: snip the chain with bolt-cutters, then the chain and the heavy industrial box are worth a bit at the dealers; trash the electronics.
When you get a multi-meter, be sure to get one that measures current. That seems to be missing from the cheaper ones, so check the specs before you leave the shop. Then when you use it for current, check you have the probes in the correct sockets on the meter: that's usually different from the volt, ohms etc holes. Also note that there's often two sockets for the red lead when measuring amps: a low current one say 500mA and higher one up to say 10A. It's prudent to start your measurement in the A range and move to the other one if the current is low enough and you need more decimals.
thehurrica:
I thought that you said that if a car passes, I'm not gonna be able to put the Arduino on a sleep mode. That's why I asked.
Well it's not like a poor sleeper that is woken up by the noise. You need some electronic arrangement to wake it up. What have you in mind?
What model you suggest to me ?
Thank you again.
As far as I know most of the cheap (£5 - £10) digital multimeters can measure currents up to 10 amps. That is more than enough for 99.99% of Arduino projects. Don't waste more money until you know that you need to. It can be useful to have 2 of them if you want to measure current and voltage at the same time, or to measure voltage in two places at the same time - hence cheap ones. One thing I would pay a little more for is the ability to measure frequency and capacitance - something I only use occasionally, but very nice to have. So only a little more. In my experience auto-ranging meters are significantly slower to react than ones where you manually select the range and that slowness can be a PITA.
Robin2:
Well it's not like a poor sleeper that is woken up by the noise. You need some electronic arrangement to wake it up. What have you in mind?
:- D
I'm planing to use the watchdog timer. Can I use it ? Cauz my plan is to put the Arduino on a sleep mode when the time clock is 8pm (the density on road traffic will decrease and there will no congestion) and woke it up on 8am (just an exemple) the time depends on the city (big, small, ...).
Robin2:
As far as I know most of the cheap (£5 - £10) digital multimeters can measure currents up to 10 amps. That is more than enough for 99.99% of Arduino projects. Don't waste more money until you know that you need to. It can be useful to have 2 of them if you want to measure current and voltage at the same time, or to measure voltage in two places at the same time - hence cheap ones. One thing I would pay a little more for is the ability to measure frequency and capacitance - something I only use occasionally, but very nice to have. So only a little more. In my experience auto-ranging meters are significantly slower to react than ones where you manually select the range and that slowness can be a PITA.
Thank you for infomations.
I think the better is to buy a good meter.
One other question gentlemen (Sorry if I'm asking a lot of questions).
Is there an ultrasonic sensor with a good range (to cover two lanes) ? cauz the ones that I've found are all with 450cm detection distance (and I think that the max distance of detection cannot exceed 3 meters)
Here's one:
So if there is ultrasonic sensor that satisfy this condition show it to me.
Thank you in advance.
You need some electronic arrangement to wake it up. What have you in mind?