How to make 24V high current DC power suppply...?

[koolguy]

Hello everyone,


I want to make a DC power supply for driving motor which require 24V and 20Amps current appr......
As before i have used AC to DC rectifiers with linear regulators 78XX max. current of 1Amps i have listen about bypass transistor across regulator to increase its current holding capabilities but transformer cost will increase too much for that, so please suggest me how to make this power supply...??

 

[tcmtech]

For power in that level your easiest solution may be to use common automotive battery chargers for the power supply.
They are cheap and easy to get plus most use a half wave bridge center tapped transformer so its possible to modify them to produce 24 volts at half their 12 volt rated amps.

Any 12 volt 40 amp or higher rated battery charger of that design would easily work as a base power source for making a 24 volt 20 amp supply just by adding a full wave bridge rectifier and the right size capacitors.

 

[cowboybob]

Your voltage and current (therefore, power) requirements dictate the transform's power rating, i.e., 480 watts. There's no magic bullet to get around needing a transformer with that output capacity.

As an alternative, I might suggest getting two cheap or used 12VDC automotive battery chargers with at least 10 amps output capacity per charger (even higher output current capacity would be better), connect their outputs in series and use that for your power supply. These units are not all that well regulated, but given that you are driving a motor, regulation ought not be a major concern.

 

[koolguy]

Is there any other method than using battery?

 

[colin55]

The best is to get a 12v battery and use a 4 amp battery charger. These are easy to get in India.

 

[tcmtech]

Is there any other method than using battery?

Yes. Read the first two posts.

 

[colin55]

A 20 amp power supply is an enormous investment and very difficult to produce. On top of that, a 20 amp motor is going to take 40 amps when loaded.

 

[koolguy]

hey are cheap and easy to get plus most use a half wave bridge center tapped transformer so its possible to modify them to produce 24 volts at half their 12 volt rated amps.

Any 12 volt 40 amp or higher rated battery charger of that design would easily work as a base power source for making a 24 volt 20 amp supply just by adding a full wave bridge rectifier and the right size capacitors.

Till now i have seen a diode pf 3Amps max in this case which diode to be used and transformer..?
I have seen SMPS they are small can't we use it??

 

[tcmtech]

I am reffering ot a common portable automotive battery booster charger not a small trickle charger.

Something like on of these can make a good cheap high current power supply with very little modifications.
**broken link removed**

 

[alec_t]

The best is to get a 12v battery and use a 4 amp battery charger.

Not quite the 20A required by the OP, Colin

 

[bountyhunter]

Hello everyone,


I want to make a DC power supply for driving motor which require 24V and 20Amps current appr......
As before i have used AC to DC rectifiers with linear regulators 78XX max. current of 1Amps i have listen about bypass transistor across regulator to increase its current holding capabilities but transformer cost will increase too much for that, so please suggest me how to make this power supply...??

Here is a new supply for $50:

**broken link removed**

 

[colin55]

You can't run a motor off a SMPS. It takes 50 amps to start. The SMPS will shut down.

The best is to get TWO 12v battery and use a 4 amp battery charger. You can even use two 12v chargers.
For a 15% duty cycle, this is all you need.

 

[tcmtech]

For a 15% duty cycle, this is all you need.

Where did anyone mention he was running at a 15% duty cycle? Did I miss something?

Personally I don't consider a 24 volt 20 amp power supply all that big or difficult to piece together from common items either but thats just me.

 

[colin55]

Personally I don't consider a 24 volt 20 amp power supply all that big or difficult to piece together

Have you ever seen a 20 amp battery charger?

 

[bountyhunter]

You can't run a motor off a SMPS. It takes 50 amps to start. The SMPS will shut down.

Then you add a big storage cap or a couple of 12V batteries.

 

[4pyros]

For someone with limited resources and money like the OP I would suggest using two 12 volt battery's and a
low current 24 volt charger to test your motors. What are you going to use on your robot for battery's and chargers?

 

[koolguy]

What are you going to use on your robot for battery's and chargers?

Will this battery will work for this motor??
**broken link removed** or **broken link removed**

 

[colin55]

It says clearly: "Discharge Current up to 12A"
Maximum safe discharge current 4000mA

So obviously it will not work for a 20 amps motor that will take up to 30 or 40 amps.

And the battery will last less than 15 minutes and will get so hot the plastic will melt.

Unless you tell us what you are doing, we are just running around in circles.
You are trying to buy a gold-plated hammer to drive a fence nail.

 

[koolguy]

OK, i was thinking to make a person sitting Robots..

 

[tcmtech]

Have you ever seen a 20 amp battery charger?

I live on a farm and I am an industrial technician. 20 amp is a small battery charger in my views.

I have a pair of 12 volt portables that can top 100+ amps continuous duty cycle each with starting peaks only limited by what the supply line circuit breaker will sustain.

I also have an old industrial 240 volt powered one that can top 1000 amps peak cranking power at 12 volts or 500 amps on 24 volt output.