voltage too low?

Hi,

I am making an RC car and this is wired as following:

  1. I took the cellboost ipr3 apart from the shell and wired everything to this positive and neg.
  2. H-Bridge pos/ground connects to cellboost
  3. H-bridge (sn754410ne) has 2 powered motors that are pretty small but can draw some current when the car gets stuck
  4. Arduino usb 5v connects to cellboost pos.
  5. Arduino usb gnd connects to cellboost neg.
    6.Arduino usb d+ and d- connects to the cellboost's usb charger d+ and d- pins (which I think are not used by cellboost)

Everything is okay'ish but for some reason, my arduino isn't recognized by computer when I connect the cellboost's usb charge to the computer (even though D+ of arduino is hooked up to D+ of cellboost charging side)

Also, when I run my motor, the motor starts up and the arduino just resets for some reason. I suspect this is a current draw problem since both problems get sorted out when I hook up the arduino/h-bridge with seperate power (instead of cellboost power).

My question is: do you think an arduino and 2 motors can be hooked up directly to the lipo (rather than via the cellboost's charging circuit) or is there a reason for having a current limiting thing in the cellboost's circuit? It was initially designed to run an ipod shuffle so I think my new circuit takes in a lot more current than an ipod does. This would mean the internal safety current limiter thing would be useless for me. However, would the lipo explode if I connect the motor to it? I am worried the 2 of them would take too much current. Here is a pic of a similar sized motor in an rc car just to get an idea:
http://www.world-trades.com/photo/929/9301/rc-car-193.jpg

Thanks!

Never ever use a lipo battery without protection against too low voltage or overloading. It might explode.
Most of the times, they can supply a large current.

Perhaps you need a larger battery, and some protection to stop the car if the voltage is too low (for example at 3.0V).
I think it is possible to run it directly from the battery, and have the Arduino keep an eye on the voltage. Only the sn754410ne needs 4.5V, so you might have to look for an other driver ic.

You could also buy a stronger switching voltage converter, like a buck boost converter. To make a stronger +5V.

Is there a way then to turn off everything in case voltage goes too low? I can turn off sn754410ne but is there a way to self destruct the arduino? I am now able to get votage reading from arduino.

To read a voltage with the Arduino, you can use two resistors as a voltage divider, and read it with an analog input.
If you choose analogReference() to be 1.1V, the Arduino measures the voltage regardless of it's own voltage.

The avr chip (the microcontroller on the Arduino board) can put itself into sleep mode.

rkrishnan2012:
I am making an RC car and this is wired as following:

  1. I took the cellboost ipr3 apart from the shell and wired everything to this positive and neg.
  2. H-Bridge pos/ground connects to cellboost
  3. H-bridge (sn754410ne) has 2 powered motors that are pretty small but can draw some current when the car gets stuck
  4. Arduino usb 5v connects to cellboost pos.
  5. Arduino usb gnd connects to cellboost neg.
    6.Arduino usb d+ and d- connects to the cellboost's usb charger d+ and d- pins (which I think are not used by cellboost)

Please draw us a schematic. From the way you describe it I think you may be screwing up the Arduino->PC communication by messing with the D+ and D- wires. These need treating with extreme care. Please, we need a drawing. And maybe a photo too if you can.