Hi,
Currently I am working on a project which has 2 DC motors, 1 Servo, Pololu sensors, Ultrasonic and Sharp IR sensor. Firstly, 2DC motors are supplied by 9V battery and Arduino is also supplied by seperate 9V battery. We have realised that the general use 9V batteries are not enugh and draining quickly. We have purchased rechargable 11.1V 1450 mAh C 25 Li-Po battery and will use this. We want to power both Arduino Mega 2560 and DC motors by this batterry together. Some friends told voltage regulatory circuit is needed.
I have searched online on this but could not find valuable information.
Do we need voltage regulator for DC batterry really?
Can you suggest links or etc. so that we can built this circuitry?
hydrv:
Hi,
Currently I am working on a project which has 2 DC motors, 1 Servo, Pololu sensors, Ultrasonic and Sharp IR sensor. Firstly, 2DC motors are supplied by 9V battery and Arduino is also supplied by seperate 9V battery. We have realised that the general use 9V batteries are not enugh and draining quickly. We have purchased rechargable 11.1V 1450 mAh C 25 Li-Po battery and will use this. We want to power both Arduino Mega 2560 and DC motors by this batterry together. Some friends told voltage regulatory circuit is needed.
I have searched online on this but could not find valuable information.
Do we need voltage regulator for DC batterry really?
Not if the motors are rated at 12vdc. The arduino external power connector does not require a regulated voltage as it is regulated down to +5vdc by an on-board regulator.
Can you suggest links or etc. so that we can built this circuitry?
The motors run from 9V?
The Mega needs 5V.
Motors can require high surge currents, such as when they stall, that can briefly drag down the voltage and cause the microcontroller to reset. Best way around that is to give the motors and the uC their own source - in this case, 2 regulators in parallel powered by the same battery.
Lots of choices here for 5V the Mega - modify a USB cable and bring 5V in there.
The Arduino has an on-board regulator, supply 11V to the barrel plug.
A lithium battery will not have any difficulty sourcing enough current
for small motors - in fact you might want to consider adding an inline fuse.
With 11V to the Arduino there is 6V to be dropped by the regulator so
it may get quite hot - if the other 5V peripherals draw a lot of current
you may need a separate 7805 regulator on a heatsink (or a DC-DC
converter).
You don't mention a motor controller - are you using one? What
voltage are the motors?
MarkT:
The Arduino has an on-board regulator, supply 11V to the barrel plug.
A lithium battery will not have any difficulty sourcing enough current
for small motors - in fact you might want to consider adding an inline fuse.
With 11V to the Arduino there is 6V to be dropped by the regulator so
it may get quite hot - if the other 5V peripherals draw a lot of current
you may need a separate 7805 regulator on a heatsink (or a DC-DC
converter).
You don't mention a motor controller - are you using one? What
voltage are the motors?
I understand now why it is suggested. Thanks. As you stated arduino may get hot because of power supply voltage(measured Li-Po voltage when fully charged is 12.6V ). Then we shold use 7805 for arduino since our board is not genuine. I may get crazy with 12.6V XD
We are using a motor driver for DC motors with 12V supply.
The LiPo battery has C 25 rating (25*1.45= 36.25 A) I think we do not need regulator,do we?
I would recommend a switching regulator for the 5V. Otherwise you're just wasting a lot of battery charge as heat in the regulator.
Say the Mega and whatever LEDs, etc you have connected need 350mA of current.
Power = Voltage x Current.
(12V in - 5V out) x .35A = power dissipated as heat = 2.45W. That regulator will be Hot! and may go into thermal shutdown.
CrossRoads:
I would recommend a switching regulator for the 5V. Otherwise you're just wasting a lot of battery charge as heat in the regulator.
Say the Mega and whatever LEDs, etc you have connected need 350mA of current.
Power = Voltage x Current.
(12V in - 5V out) x .35A = power dissipated as heat = 2.45W. That regulator will be Hot! and may go into thermal shutdown.
Thanks,
I decided to use 2 seperate Regulattor circuitry. 7805 for arduino and 7809 for Dc motors.