I have purchased the Arduino starter kit for my son and we enjoy it. Trying to get him started at a young age. To be honest, I find it very interesting also and am learning with him to a certain extent.
I recently purchased a OSOYOO robot car because he is more interested in that:
The kit comes with a battery holder for 2x of the 18650 'laptop' batteries which connects them in series. The voltage reader with the kit says approx. 8.XX VDC or so when fully charged. The turning of the car is controlled on the car by having left and right side wheels turn opposite directions, IE: right side CW, left side CCW. The tires that came with the kit were creating too much friction and it would not turn (motors just made buzzing sound). I ended up removing the tires and running it on the plastic rims, turned fine due to they can now 'slip' on the hardwood floor in our home. Ran fine forward and backwards.
Next step in the project was to integrate infrared control. Got it up and working. I recall reading Arduino needs threshold voltage above 7VDC or so and was worried 8.XX is too close to that. I ordered a battery holder that is for 3x 18650, so voltage is now at 12.XX VDC. Motor shield and Arduino both power up fine, and infrared controller still works, but only to rotate the car left or right. When I use the button for forward or back on the infrared remote, all power 'shuts off' to Arduino and the motor shield (LED's turn off on shield and Arduino). The motors seem like they start to turn, then immediately everything powers off. Doesn't matter if I hold the car in the air or place it on the counter.
My question is why is the 12.XX VDC battery pack able to rotate the car left or right, but now it cannot go forward or back as it did with 8.XX VDC? Once I hit forward or back, all LED's shut off. Was moving forward and back with the 8.XX VDC batteries. Once I remove one battery (break connection) and then reconnect, all LED's turn back on and it will start turning left/right on command again but will 'shut off' when I try to command forward or backward. I tried to run Arduino off of the programming cable, and just run the motor shield with 12VDC, the LED's come on, but nothing happens when I press the buttons on the infrared controller.
Really appreciate any help you guys/gals can give. I have a couple ideas what may be happening but don't want to sound too stupid on my first post. Sorry in advance if my information is too spotty.
Too few volts may prevent a circuit from operating correctly, but it's quite rare that it could do the circuit any harm. To many volts, on the other hand.... Let's hope you have not permanently damaged anything. Ask here first, is the moral of the tale.
The Arduino will be fine with 8.2~8.4V. Even at the nominal 7.4V of two li-ion batteries, it should be perfectly ok. At voltages lower than around 6.5V, the Arduino's regulator might not be able to provide the normal 5V, but the Arduino will usually carry on working for quite some time.
I will move back to the original battery case. If I get it running again my kid will think I'm a super hero.
I used an Arduino to power a R&D project I had to automate on the fly and I recall using a 9 VDC power supply to the power jack. For reference, what are the limits on Arduino supply voltage?
Also, why is the power cutting out like it is? Almost seems like something is tripping then resets once I remove and reinstall the battery.
The barrel socket on the Uno is connected to its on-board regulator which needs at least 6.5~7V to produce a 5V output. If it gets less than around 6.5V, is output will be less than 5V, probably around 1.5V less than its input. But the ATmega chip and the other circuits on the board can usually run at significantly less than 5V. However, there is no guarantee that they will. The ATmega chip can in fact run right down to 1.8V, but not at 16MHz! The higher the clock speed, the higher the voltage needs to be to enable it to run reliably.
The upper limit is governed by different factors. The regulator's job is to produce a 5V output from any voltage above about 6.5V. in theory, it can probably do this up to perhaps 20V input. But the higher the input voltage, the more work the regulator has to do to get it down to 5V. And the more current it has to supply, the more work it has to do. That work results in heat. Too much heat can cause the regulator to shut down and possibly be damaged. So you will see different figures quoted for the maximum voltage, maybe 12V or even 20V, but none of them is guaranteed to be safe because it also depends how much current is being drawn. The "best" voltage to use is probably around 7 to 8V. But better still is to provide a regulated 5V supply to the 5V pin, bypassing the barrel socket and regulator.
As for your problem of cutting out, impossible to say without more detail from you. A schematic, links to the major components etc. But some component overheating and shutting down to try to protect itself would be a good guess.
I have the same Osoyoo robotic car I'm helping my daughter put together.
On the wheels, we found that reversing the upper screw (when the car is sitting properly) so that the nut is on the inside and the lower screw with the nut outside but with one of the plastic spacers on the inside to bring the end of the screw in more. All screws were rubbing against the inside of the rim.
However we have only had the car move fwd, rev, left & right (lesson #1)...one time. I've added serial debugging to the code, just to be better understand where it is faulting, and it is at the end of the delay() in my case and after whichever set of directions happen to be first (fwd, rev, left or right); this was determined by commenting out the appropriate lines as necessary. So, not a matter of direction (didn't think it would be) but rather something about the very end of the delay as the motors run the intended duration in the proper direction depending on what was provided.
I am curious. I have seen this same car chassis with 2-wheel drive without the arduino components/shields for sale. It has a battery box for four 6v batteries. Is the need for 2 3.7v batteries with this kit based on the additional functions such as the sensors? Could someone explain this to me, please?
24V? Don't you mean four 1.5V batteries/cells, making 6V in total?
The advantage of the li-ion cells over the regular cells is not just the slightly higher voltage, although this is useful. The li-ion cells are rechargeable, which not all regular cells are of course, but also their energy density is much higher, relative to their size and weight.
Unfortunately you need a specific charger for li-ion cells, you cannot recharge them in a charger for ni-mh cells.
Yes, that is what I meant, a total of 6v. But, I am wondering about the use of the chassis with the same motors as in this kit. What would be it's purpose. Could I build the same car with it? I doubt it if 2 3.7v batteries are required just to run the motors. And, if so, I don't know why this other product is on the market. Any thoughts?
Why don't you post links to the 2 motor and 4 motor versions of the kit? Then perhaps we can discuss the advantages and disadvantages of each. Please use the insert link icon so the links are clickable.
There is a complete 2w drive kit and there is a 2w drive kit with a 4 1.5v battery kit. My question is if the complete kit needs 2 3.7v batteries, what is the purpose of the kit with 4 1.5v?
The two kits are made, or supplied, by different vendors. They are targeted, I guess, at slightly different customers. But the marketing strategies are probably not well thought-out.
The "complete" kit may be aimed at beginners, or near-beginners. It includes an Uno clone, which, because it runs at 16MHz, needs at least 6.5V to power it via it's barrel-jack. Hence the 2 x 3.7 battery pack. The 4 x 1.5V pack would not, in theory, provide enough voltage to run the Uno. But most beginners probably won't have any 3.7V li-ion batteries or a charger for them. I wonder if the same vendor sells both of those things also...?
The more basic kit may be aimed at slightly more knowledgeable customers. They will know that a 16MHz Arduino will almost certainly run fine at 5V, if you power it direct through the 5V pin rather than the barrel-jack. 4 x 1.25V NiMh rechargeable batteries would be ideal, but 4 x 1.5V non-recheargeable batteries would be too much voltage and could damage the Arduino. More experienced customers will also know that an 8MHz Arduino is a much better choice than a 16MHz Arduino, extending the battery life greatly, and that an 8MHz Arduino is still more than powerful enough for most projects involving this robot. They probably also know that far more powerful Arduino are now available, based on the Arduino Zero or M0 or ESP8266/32 designs, which also run at 3.3V rather than 5V.
Which would I buy? Neither. Which would I choose if offered one or the other for free? Probably the more basic model, giving me more flexibility to design the rest myself.
