Robot projet, battery problem

[lerameur]

hello,

I would like to know if what I am getting is normal or if I have flaws
in my design
I have a 12v (12.87) battery, It is hooked up to and H-bridge (L298N)
with the diode as shown on the specsheet. I used fats recovery diose
100v 8A cause thats I had. When I check the voltage on the motor while
it is running, it is about 10v. I am osing volts here, And the motor
due turn slower, Is there any way I can have the motor closer to the
12.84v mark ( or the battery voltage ?)

Ken

 

[Tom Biasi]

hello,

I would like to know if what I am getting is normal or if I have flaws
in my design
I have a 12v (12.87) battery, It is hooked up to and H-bridge (L298N)
with the diode as shown on the specsheet. I used fats recovery diose
100v 8A cause thats I had. When I check the voltage on the motor while
it is running, it is about 10v. I am osing volts here, And the motor
due turn slower, Is there any way I can have the motor closer to the
12.84v mark ( or the battery voltage ?)

Ken

Hi Ken,
You are getting a couple of junction drops. If you can't tolerate it, put
more in.

Tom

 

[ehsjr]

hello,

I would like to know if what I am getting is normal or if I have flaws
in my design
I have a 12v (12.87) battery, It is hooked up to and H-bridge (L298N)
with the diode as shown on the specsheet. I used fats recovery diose
100v 8A cause thats I had. When I check the voltage on the motor while
it is running, it is about 10v. I am osing volts here, And the motor
due turn slower, Is there any way I can have the motor closer to the
12.84v mark ( or the battery voltage ?)

Ken

Take a look at the datasheet for the H-bridge
saturation voltage. The bridge is where the
voltage is dropped, and it is normal.

Ed

 

[lerameur]

Take a look at the datasheet for the H-bridge
saturation voltage. The bridge is where the
voltage is dropped, and it is normal.

Ed

Thats what I thought, but it is a bit more then I anticipated.
I would need a 15 volt car battery for my project.
Could I use a car battery and a small 3v battery pack in series ?

k

 

[Tom Biasi]

Thats what I thought, but it is a bit more then I anticipated.
I would need a 15 volt car battery for my project.
Could I use a car battery and a small 3v battery pack in series ?

k

Not a good idea. The car battery can put out tremendous current compared to
the little 3 V. pack.
Bad things might happen.
Look into the 14 or 18 V NiCad packs they use for power tools.

Tom

 

[lerameur]

Not a good idea. The car battery can put out tremendous current compared to
the little 3 V. pack.
Bad things might happen.
Look into the 14 or 18 V NiCad packs they use for power tools.

I need 6 hours of run time, for the motor, laptop, spectrum analyzer.
So I really need something big. do they make 3v smal lead acid
batteries ? if so would that do ?
Mayb i should look into 24v car battery and use voltage dividers??

ken

 

[Tom Biasi]

I need 6 hours of run time, for the motor, laptop, spectrum analyzer.
So I really need something big. do they make 3v smal lead acid
batteries ? if so would that do ?
Mayb i should look into 24v car battery and use voltage dividers??

ken

If you are going to series batteries they should be of the same chemistry
and AH rating.

Tom

 

[Eeyore]

Thats what I thought, but it is a bit more then I anticipated.
I would need a 15 volt car battery for my project.
Could I use a car battery and a small 3v battery pack in series ?

Why not use mosfets in your bridge. You can get less voltage drop with them.

Graham

 

[lerameur]

Why not use mosfets in your bridge. You can get less voltage drop with them.

you mean change H-bridge ?
which one do you recommend ?

k

 

[Jonathan Kirwan]

If you are going to series batteries they should be of the same chemistry
and AH rating.

Yes. I think there are still 6V motorcycle batteries around. 3 of
those would get to 18+V. Also may be able to tap off at the 12V point
for the rest, leaving the 18V for the motor supply rail.

Jon

 

[jasen]

I need 6 hours of run time, for the motor, laptop, spectrum analyzer.
So I really need something big. do they make 3v smal lead acid
batteries ?

closest values are 2.2V or 4.4V

if so would that do ? Mayb i should look into 24v car battery and
use voltage dividers??

use DC-DC converters, dividers are extremely inneficient.

Bye.
Jasen