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Replacing batteries by AC or DC adaptor

drummerdimitri

drummerdimitri

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Hey guys,

I was just wondering if one could replace the use of batteries in any electronics with an AC or DC adaptor or maybe even a switching adaptor. For example: My 445 nm laser pulls around 2.2 A from my 4.2V battery. Could it be okay to connect a power supply of 4.205 V, that can supply a maximum current of say 3 or 1 A?
I am asking this because I want to transform some build from being a portable handheld to a labby style. If this is not possible, then how exactly should i approach this?

Thanks!
 





bobhaha

bobhaha

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You can use an AC to DC wall converter but the current must exceed the needed current by the laser. For example if the laser pulls 2.2A you would need at least a 2.5A wall adapter. You must make sure the output voltage is constant and within the drivers limits. So a 4.2V AC-DC converter with at least 2.5A output is great.
 
LaZeRz

LaZeRz

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Word of warning:

Make sure you measure the voltage coming from your ac/dc adapter and add a capacitor if possible. I have a "12v" AC/DC and it outputs over 20 volts.
 
drummerdimitri

drummerdimitri

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LaZeRz said:
Word of warning:

Make sure you measure the voltage coming from your ac/dc adapter and add a capacitor if possible. I have a "12v" AC/DC and it outputs over 20 volts.
Click to expand...

Don't worry, I always measure the voltage of the adaptor before connecting it to any source.
I have two cheap chinese adaptors that can be voltage regulated and output twice the voltage they are rated at. I can accurately test voltages to 4 decimal places so that shouldn't be a problem!
 
drummerdimitri

drummerdimitri

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bobhaha said:
You can use an AC to DC wall converter but the current must exceed the needed current by the laser. For example if the laser pulls 2.2A you would need at least a 2.5A wall adapter. You must make sure the output voltage is constant and within the drivers limits. So a 4.2V AC-DC converter with at least 2.5A output is great.
Click to expand...

If the current does not meet the requirements of the driver, how would that affect the output power? I am guessing it would just not be as powerful as it should be.
Also, would there not be any danger of using a 3A output if the driver is pulling 2.2A from the batteries? I know that a drive pulls as much current as it needs to, but what if the battery is limiting its discharge rate to protect itself?
 
LaZeRz

LaZeRz

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Might fry the adapter if you suck too much current from it ;)
 
bobhaha

bobhaha

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drummerdimitri said:
If the current does not meet the requirements of the driver, how would that affect the output power? I am guessing it would just not be as powerful as it should be.
Also, would there not be any danger of using a 3A output if the driver is pulling 2.2A from the batteries? I know that a drive pulls as much current as it needs to, but what if the battery is limiting its discharge rate to protect itself?
Click to expand...

Yup... you will damage the wall adapter. Some adapters have a feature that will stop all output to the driver and it just simply will not work.
 
Last edited:
LarryDFW

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drummerdimitri said:
If the current does not meet the requirements of the driver, how would that affect the output power? I am guessing it would just not be as powerful as it should be.
Also, would there not be any danger of using a 3A output if the driver is pulling 2.2A from the batteries? I know that a drive pulls as much current as it needs to, but what if the battery is limiting its discharge rate to protect itself?
Click to expand...

Only use "switching power supplies", since they are voltage regulated.

Most switching plug in supplies will deliver ~10% over the rated current.

Voltage will sag a little at that over-current level.

Loads less than the rated current are fine.

LarryDFW
 
Last edited:
hakzaw1

hakzaw1

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good topic- wallwarts are everywhere- scrap only pays 10cents a pound for them- I recyce for use not grinding them up --duh!
I dont trust the numbers on the labels.

ty for the info all.. tell me more- hak
 
sinner

sinner

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How much of a labby do you want actually?
Lab styles are usually made for the functionality of it and a continuous duty. If thats
what you desire, you cant get away with just a wall-wart adaptor.. You would only be
powering the laser off a dc source and thats it.. The driver&LD would still overheat and a
duty cycle is necessary, So it will not actually be a labby i think!!!
 
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