Isn't 9v going to hurt a 6v motor?
I'm building a new robot using the chassis of a swap meet remote control car (Wikipedia says the motors want 6v). The brains will be an Arduino Duemilanove and an Adafruit Motor Shield. I've read the user manual for the Motor Shield, but still have a couple questions. I've tentatively run the motors off 4.8 volts and it is enough juice to go forward and backward but not enough to turn. I'm afraid to burn up the motors since I have no experience with 6v motors.
Stuff I've read and understand:1) The Arduino and Motor Shield will run off one 9v battery.2) The motors will work better with their own battery source and that battery source will never go through anything other than the motors. I don't have to worry about that going through any electronics.
What I need help understanding:1) Can I daisy chain 5, 1.2v rechargeable batteries for 6v and plug that into the external power terminals to run the motors? Is there a better rechargeable 6v battery out there with enough MaH to last a day and then recharge at night?
2) There is a jumper to run the motors off the same 9v that runs the Arduino and Motor Shield. Isn't 9v going to hurt a 6v motor?
I decided to use a shield because it makes my life a lot easier and I still have enough pins left for the rest of my sensors.
The toy came with a, "TYCO R/C 6.0V Jet Turbo" rechargeable NiCd battery pack (rated at 700 MaH... wiki says it would charge for 8 hours and then run for 20 minutes.) So I'm guessing the motors run close to 6v, if not a little under that.
I don't know what the current needs of the motors are, but the battery only had .7A so that has to be the max, right?
The L293D delivers .6A according to their data sheet which is .1A under the max the old battery delivered. If that .1A is a problem I have read that you can piggyback L293Ds to double the current if you need to. I'm not sure what that does as far as restricting heat dissipation though. I'm guessing it's nothing good.
Another option is to replace the L293D with SN754410 motor driver ICs which is rated for 1A which will work for sure but it doesn't have the kick-back protection the L293D does (I have no idea what that means or why it is bad).
Sorry about the ambiguity of "all day." I hope to run the robot 8 hours a day and recharge it over night for the next day. The motors would probably be running about half that time. So, its duty cycle would roughly be 1/6. I'm hoping 6v at 2450MaH would do that?
I opened up the toy and the motors don't have any markings on them at all. The main body and the bottom look kind of like aluminum and the top is a white plastic. Not very helpful, but looks pretty cheap.
I don't think this was a high quality toy but I think it'll make a pretty nice robot platform. It's light, has tank style steering on four wheels but it does have a funky little gear linking the two left and two right wheels. I just need a little help figuring out how to handle these motors.
Forgot to ask. What's the advantage of the 7.2v NiMH battery pack over 6 AA 1.2 NiMH batteries run in series? Would I just choose whichever has the better MaH?
The toy came with a, "TYCO R/C 6.0V Jet Turbo" rechargeable NiCd battery pack (rated at 700 MaH... wiki says it would charge for 8 hours and then run for 20 minutes.) So I'm guessing the motors run close to 6v, if not a little under that. I don't know what the current needs of the motors are, but the battery only had .7A so that has to be the max, right?
Must have been a problem with Amps... just weird that it would start off working and then quit like that.
I did measure the current at 0.99A at stall. On the Adafruit Motor Shield's "Use it" page is says piggybacking the ICs will double current to 1.2A so I went with that because it's over 1A and then I'd also still have the kick-back protection. If it starts to shut itself down again I'll heat sink it. I didn't realize the IC was shutting itself down, I just thought it wasn't giving enough current to the motors to move them which confused me because it was moving them 10 seconds ago before it quit on me.
It looks like they made most of the top of the PCB a giant heat sink and ran as many traces as they could on the bottom layer. This must be a different version of the shield than the one that's on the Motor Shield's page in their shop.
Whenever I'm concerned about heat from a shield, I just add an extra stack header to the layers. Not sure how effective it is, but it makes me feel better about it.
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