I am building a rover, with 2 TT motors (Sparkfun TB6612FNG Driver), a DHT11 Sensor, Ultrasonic Sonic Sensor, and a Servo Motor. I need to power this project for 4 hours. Please assist me with the power source I should use for all peripherals. I have seen other posts, and what I've gathered from them is that using 4*1.5V AA batteries with a 5V converter would be the best option for the Arduino and the ultrasonic sensor, but I still have doubts. Please assist.
You need to start by measuring the consumption of your various components. How much current do the motors draw when moving the rover at typical speeds over typical terrain? That's probably going to be the single most important measurement. The Uno and sensors will draw only a little current by comparison, but go ahead and measure those also.
Bear in mind that any voltage conversion you need to do will not be 100% efficient. Linear regulators can be very inefficient. DC-DC "buck" and "boost" converters will claim high efficiently number, but that's always a maximum and will be less efficient in practice. I would assume 80% efficiency.
Regarding AA batteries, if you plan to get through a set of batteries every 4 hours, it would be a crime against the planet to use non-rechargeable batteries. Rechargeable batteries like NiMH have a lower voltage, so 4x cells will be more like 5V than 6V, so ideal for powering Uno.
Well as per the motor documentation this is it's current draw at different RPM's and voltages:-
At 3VDC we measured 150mA @ 120 RPM no-load, and 1.1 Amps when stalled.
At 4.5VDC we measured 155mA @ 185 RPM no-load, and 1.2 Amps when stalled
At 6VDC we measured 160mA @ 250 RPM no-load, and 1.5 Amps when stalled.
So, I guess I'll be wanna running it at 6VDC, and I think I should have a battery suppling more then 160mA because I'll obviously have a good amount of load.
Arduino Uno, Sensors, and HC-05.:-
I'm building this project as a school project, without any support of the school, and I don't have any equipment to measure current draw, nor do I have the budget. I can only estimate the current draw. Also, I forgot to mention, I'm using a HC-05 bluetooth module too, which may draw some current too.
Please tell me options for the power that are cheap, and cost efficient, cause our school is not providing anything except the Arduino Uno. They expect us to be "thrifty".
Regarding the DC-DC boost converters, I think they are at least more efficient then the built in 5VDC converter?
If I use AA batteries, I would obviously use rechargeable, although I'll still need to use 4 batteries and step-up as 1.2V is the average output when fully charged. I can also step-down by putting 5 batteries.
Can I use a 12v or 7v Lithium Battery pack, and then connect them? Would that be a good idea? Also, should I have separate batteries for the motor and the servo motor?
Use worse case when calculating battery size.
Use lipo equivelant.
Converter for drop to Arduino.
What do you mean by LiPo equivalent and converter for drop to Arduino, please elaborate.
Here is a very simple option with NiMH batteries.
You can connect the HC-05 to the UNO 5V output.
No buck or boost needed.
Should last more than 4 hours.
Ah requirements...converter 7.4v to 5v or whatever
AA batteries will keep you poor.
Lemme see this one, looks, good. But I want the motors to have more voltage (6v).
I can just add 1 more AA battery right, to increase voltage for the motor?
Look at how most rc cars/ rovers etc are powered.
There is a good reaon why they use say 7.4v lipo battery.
Yes. But would I need separate batteries for the Servo Motor and the Arduino & the Motors?
Ya. I wanna make it so that they are easily chargeable and I don't need to remove the batteries. But would I need to use separate batteries for the Motors, and Servo Motor, and seperate batteries for the Arduino? There is also a space and weight constraint.
Same question again. What about the SG90 Servo? Where would it's power go?
Lemme try this.
Thanks for the quick answers...I really appreciate it cause I need this project's basis complete quickly. Let me test this, and get back to you! Really helpful.
Servo is fine, it's an SG90 with a light load. Motors would require more, which you have solved, again thanks a lot.
You can test it with regular AA if you don't have the NiMH batteries yet.
The output marked 4.8V will be 6V and that can go to the motors and servo.
The output marked 7.2V will be 9V and that can go to Vin.
It won't last as long as the NimH batteries.
Ok. By the way, why wouldn't it last as long?