I want to drive two same 24v 5A(full load) Dc motors with pwm using 2 hbridges for each motor. I have two 12v 18Ah sealed lead acid batteries which will be in series to make 24v. Can i connect batteries directly to h-bridge or should i use a current regulator or any other circuitry between the battery and the driver circuit.


closed as unclear what you're asking by Bence Kaulics, Eugene Sh., Voltage Spike, Dmitry Grigoryev, Daniel Grillo Aug 17 '16 at 16:57

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  • \$\begingroup\$ How are you going to generate your PWM? \$\endgroup\$ – Eugene Sh. Aug 17 '16 at 14:43
  • \$\begingroup\$ Using atmega 16 microcontroller ic \$\endgroup\$ – Sabheeh Ali Aug 17 '16 at 14:49
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    \$\begingroup\$ So what is "directly" in your terminology? Schematic please. \$\endgroup\$ – Eugene Sh. Aug 17 '16 at 14:51
  • \$\begingroup\$ By the word "directly" i ment connecting the terminals of the battery (combined in series) to h-bridge. \$\endgroup\$ – Sabheeh Ali Aug 17 '16 at 14:53
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    \$\begingroup\$ I would say "yes", but the lack of the full picture voids the warranty. \$\endgroup\$ – Eugene Sh. Aug 17 '16 at 14:53

Yes. No need for voltage regulator or similar. Voltage would be ~24V minus some voltage drop on transistors on H-bridge, so it is safe for motor, because this is the voltage the motor is rated for.


As others mentioned, you can connect your batteries to your H-bridge directly. However, it also depends on what you are really trying to do. If you are just generating PWM for your motors (without ANY feedback, such as encoders) then as your batteries discharge you will see lower performance of your motors - for example lower revolutions per minute.

Let's say at 24V and 80% PWM you have ~100RPM's. As your batteries discharge, at 20V and still 80% PWM you might have 80 RPM's or less momentum (we don't know what you are trying to do with your motors).

The drawback of powering H-bridge directly from power source is that the motor performace is dependend on the battery voltage and you might want to use any feedback, for example an encoder to measure RPM's. When your battery level drops -> your RPM's drop then you just increase your PWM to keep RPM's at constant desired level.


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