Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: rahulmagoo on December 22, 2008, 10:37:57 AM

Title: batteries discharging
Post by: rahulmagoo on December 22, 2008, 10:37:57 AM
Hello,

I'm using four 4.2V batteries(Li-ion) to derive my motors(stepper motors)...I'm using L298 as my motor controller.
When i connect my batteries the motors run for few seconds then they stop as my batteries discharge very quickly...when i check the voltage ratting through multimeter..the voltage was changing(it was increasing).
Can any one please help me why is this happening.

Thanks
Title: Re: batteries discharging
Post by: pomprocker on December 22, 2008, 12:39:03 PM
Do you have a large capacitor in series to regulate the voltage?
Title: Re: batteries discharging
Post by: rahulmagoo on December 22, 2008, 12:42:19 PM
No I've not connected any cappacitor...the batteries are directly connected to the motor driver and this driver is driving the motors.
Title: Re: batteries discharging
Post by: ArcMan on December 22, 2008, 03:13:13 PM
The increasing voltage you see may be due to the build-up of surface charge.  When a battery is at low charge and you remove the load from it, the voltage will increase for awhile.
Title: Re: batteries discharging
Post by: Trumpkin on December 22, 2008, 04:01:33 PM
Check to see if you have a short.
Title: Re: batteries discharging
Post by: rahulmagoo on December 23, 2008, 01:01:46 AM
No there is no short circuit...the circuit is absolutely fine.
Title: Re: batteries discharging
Post by: Admin on December 28, 2008, 01:05:14 AM
Quote
to derive my motors(stepper motors)...I'm using L298 as my motor controller
The L298 doesn't work with stepper motors (well, at least without a complicated circuit). You need a stepper motor driver.
Title: Re: batteries discharging
Post by: rahulmagoo on December 31, 2008, 04:01:38 AM
No the circuit is not complicated..I've copied the circuit as it is from the datasheet of L298..so there is no problem with my circuit...why L298 won't work with stepper motors?? what are the problems using L298?? can u suggest any other motor driver.
Title: Re: batteries discharging
Post by: Admin on January 09, 2009, 04:49:37 AM
What schematic? I'm telling you, the L298 won't work with steppers! ;)

And even more, the L298 datasheet says it requires at least 4.5V.

A 4.2V battery won't cut it. ;D