Autonomous Truck Motor Power Help Requested

Hey, I am following this instructable http://www.instructables.com/id/RC-Car-to-Robot/?ALLSTEPS I have everything put together correctly and have a bigger truck than he started out with. The problem I have run into is my ping))) sensor only turns on (led indicator flashes) when the rear motors are switching from backwards to forwards. I would assume this is because the motors are taking up the voltage needed by the ping))) sensor. I have two nine volt batteries powering my project ( one 9-volt connected to arduino uno and one 9-volt connected to the motor shield). If the problem is what I suspect, is there any way to limit how much of the power input that the motors use? Thanks so much!

[EDIT] When plugging in the 9v to either the Uno or the Motor Shield AND plugging in a usb connected to the computer into the Uno, I get the result I want.[EDIT]

cherryguy:
I have two nine volt batteries powering my project ( one 9-volt connected to arduino uno and one 9-volt connected to the motor shield).

If you’re using those PP3 9 volt batteries to power a motor then I suggest you stop right there. Those batteries are a hideously expensive way to power things - they have very low current capacity, hold very little charge and to add insult to injury the voltage regulator on a standard Arduino will be throwing a substantial part of that tiny power away as heat. Chuck those and replace them with a battery box and some AA batteries and you’ll get a much cheaper and more reliable power supply.

Thanks, but I doubt that will solve my ping))) sensor problem.

We dont doubt it and at the very least it changing to AA batteries for the power side of yournprojectbwill give you a sustainable way forward. PP3 batteries are a dead end andnif they are not the problem today, they will be tomorrow.

If you check the two servo related links in my signature below you will see a demonstration of the problem and a solution.

Duane B

rcarduino.blogspot.com

cherryguy: Thanks, but I doubt that will solve my ping))) sensor problem.

Really? You can't see the connection between an inadequate power supply and some of your sensors behaving as if they are not getting enough power?

Thanks, but I doubt that will solve my ping))) sensor problem.

You'd be the only one doubting it, then.

DuaneB: We dont doubt it and at the very least it changing to AA batteries for the power side of yournprojectbwill give you a sustainable way forward. PP3 batteries are a dead end andnif they are not the problem today, they will be tomorrow.

If you check the two servo related links in my signature below you will see a demonstration of the problem and a solution.

Duane B

rcarduino.blogspot.com

Thanks all! I guess I was being ignorant :P The brand new 9 volts did die fairly quick (about 3 hours of running the arduino uno and motors) so i guess I will try AAs and see how that works. Will post back with updates and if its all good I'll even post a video! :D And Duane, thanks for those links in your signature, I saw you talking about them in another forum and it switched my thinkings about 9-volt batteries.

DuaneB: We dont doubt it and at the very least it changing to AA batteries for the power side of yournprojectbwill give you a sustainable way forward.

Hey, switched to four AA rechargeable batteries to power the Uno. I am having the same problem as before and when I try to power the motor shield with four other AA batteries the wheels do not turn unless I pick the truck up off the ground. Any other ideas? Oh I also tried using a 5v Regulator and a 9v battery to power the ping and that sometimes works as desired but not other times, as if pin 7 isn't giving the pulses that tell the senor to start.

s the wheels do not turn unless I pick the truck up off the ground. Any other ideas?

What is the mass of the truck? The specs of the motors? Have you tried C or D cells?

cherryguy:
Hey, switched to four AA rechargeable batteries to power the Uno. I am having the same problem as before

How are the batteries connected? Using four rechargeable batteries you would need to connect them to the 5V line. If you connect them to Vin that’ll go through the voltage regulator and the resulting voltage will be too low.

cherryguy:
when I try to power the motor shield with four other AA batteries the wheels do not turn unless I pick the truck up off the ground. Any other ideas?

What voltage do the motors need?

AWOL:

s the wheels do not turn unless I pick the truck up off the ground. Any other ideas?

What is the mass of the truck? The specs of the motors? Have you tried C or D cells?

I don't have much info on the motors as they came with the truck, I took the shell off of the truck and the shell probably weighs more than the added weight of the batteries and boards. No I haven't tried C or D cells but their size makes them quite impractical to use on my truck.

So, an umbilical

PeterH: How are the batteries connected? Using four rechargeable batteries you would need to connect them to the 5V line. If you connect them to Vin that'll go through the voltage regulator and the resulting voltage will be too low.

What voltage do the motors need?

The batteries are indeed powered through the DC power jack through a plug.

The motors run well off a battery pack that came with the truck that is 7.6V. Haven't tried using the battery pack that came with it to power the motors, maybe I should look for it.

[CORRECTION] Its actually a 6V Rechargable Ni-MH Battery Pack.

AWOL: So, an umbilical

Never heard that term used for it... if you must have a picture of the robot I could upload one.

No, I mean if your truck can't carry its own power, then the power should come from an umbilical

AWOL: No, I mean if your truck can't carry its own power, then the power should come from an umbilical

Ah, meaning the batteries are held in a place besides on the truck? Excuse me for being a newb :P