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hardikcool
05-22-2009, 08:35 PM
hi friends,
i am having motors that at max load pulls 9 amp each or else around 1 amp....
and d batteries which i have is only 1.2 Ah so how much current is drawn max from it??
and m nt happy with its performance may be because of the battery...
which battery should i go for?

suhasm
05-22-2009, 09:05 PM
Why not use mini lead acid batteries?

robonics
05-22-2009, 11:37 PM
Hi
I guess you are using 6 V 1.2AH lead acid batteries.
The current rating 1.2AH means when fully charged it can maintain the voltage of 6V if you draw a current of 1.2 A for an hr.

You can as well drive a 2.4 A load with it but according to the ratings the battery can maintain the voltage for 1/2 an hr.

So in your case where the maximum current rating is 9A , if you driving your motor at peak load , the battery will last for 7 mins approx according to calculations . But practically it wont even last that much.
If it is 1A otherwise it should last for atleast 45mins..Remember the battery never lasts as the rating promises. !!

YOu could go for higher rating Lead Acid batteries. The one found inside the UPS lasts very long. Its 12V 7 AH.

hardikcool
05-23-2009, 08:45 AM
i am using 12 V but dont know why it is not giving that much satisfaction

here are the 2 motors that i am using:
http://robokits.co.in/shop/index.php?main_page=product_info&cPath=2_3&products_id=186&zenid=oesehtujm9oii1tgin9p8s1s74


but it doesnt seem to be giving that torque..........it cant move even 3-4 kgs!!!
m using differential drive on the track system....

please help me..

robonics
05-23-2009, 09:58 AM
You are using 12V what batteries ?
Lead acid or NIMH or Liion .. make sure you have charged it properly..
If you are using Lead acid battery you can charge by directly rigging it to the 12v adapter .. It will work fine ..

hardikcool
05-23-2009, 10:52 AM
yes i am using lead acid batteries...

robonics
05-23-2009, 12:43 PM
Then I guess it must supply the demand ...
Test the amount of current your motor draws and then choose the battery .. You can also test it by hooking up your motor to your DC adapter..

If it draws more current go for a battery of higher rating..

pranavtrehun007
06-01-2009, 03:08 AM
Hi hardikcool,

You can try using a battery eliminator. If they dont work with that, then there is something wrong with the motors. If you can get an SMPS, that will be awsome (maybe get it on rent before buying it). two motors with that kind of torque should be easily able to carry ATLEAST 16KG of weight.

Also, which motor driver are you using? it could be that the driver is not high current. You would need a driver that can handle 9.5- 10Amps for each of the motors.

Were you able to get the torque from the motors? i too wanted to buy those motors but after reading your post, i dont know if it would be a good choice. Please let me know your results so far and the motor driver that you are using :D

Pranav

hardikcool
06-01-2009, 09:45 AM
actually i am not getting the powerful battery so cant say whether it will give that much torque or not and other prob is 1 of the motor seems to be a little slower than the other so bot constantly takes left turn although m pushing it straight.........

and also i am not using any motor driver coz its wired one right nw......

pranavtrehun007
06-01-2009, 04:47 PM
1 of the motor seems to be a little slower than the other so bot constantly takes left turn although m pushing it straight.........

and also i am not using any motor driver coz its wired one right nw......

split the power distribution into two parts.
attach more batteries to the slower motor and see the combination that gives you a nearly straight trajectory . Also, consider starting with a smaller robot and then move to a bigger project..... i am just curious, what are you trying to build? :roll:


there may also be a safety issue here (but i am not sure). plz research the maximum current draw that your battery supports.

hardikcool
06-02-2009, 11:19 AM
@pranavtrehun007:
thanx 4 d suggestion i will definitely work on that and btw i have already made many smaller projects thats y i m nw with a big gun!!

trying to make a perfect combination of all terrain and robo -war machine and i am very near to it.....

suhasm
06-02-2009, 07:43 PM
split the power distribution into two parts.
attach more batteries to the slower motor and see the combination that gives you a nearly straight trajectory .

uhm....i dont think that is a very good idea.
Adding extra batteries to increase or decrease the speed would be a very inefficient way to do it. Motors dont have a linear Voltage vs RPM curve also. A better solution would be to use PWM to control the speed of the motors and then set both appropriately to get them both running at the same RPM.

rao
06-03-2009, 12:16 PM
PWM is a fantastic idea as it also ends up saving battery life.

One of the major problem with two motor (differential) drive is making the robot go in a straight line.

As suhas said, applying different signals to both motors will solve your problem


Rao

hardikcool
06-03-2009, 02:54 PM
PWM is a fantastic idea as it also ends up saving battery life.



Using PWM may reduce speed also and i cant let the speed go down and also the bot is completely manual........

so using these things on this bot is a bit undesirable according to me!!!

vikas
06-03-2009, 06:24 PM
With Different PWN signal you can actually make the bot go straight if motors are out of alignment. Thats how its professionally done ...

100% duty cycle pwm is nothing but DC :) , and no speed loss.

For batteries , i think these motors will be able to handle the weight of lead acid batteries quite easily.

rao
06-04-2009, 04:26 AM
Search for the 555 PWM circuit. Make one for each motor. Use the pots to tune the speeds seperately. The robot will still remain manual and the PWM circuit dont require uCs, 555s are quite cheap and the circuit is quite easy.

Rao