Using a battery charger to power a diode...would it work?

[joeyss]

Okay guys this might be the random idea of the week...

Let's say I have one that gives 4.2 V at 600 mAh and the termials are easy to connect and get a + and - out of. Could I power a heatsinkined 445 or a 635nm with it and make a lab style build that runs of wall curent? I mean provided you check the current and make sure there are no spikes beforehand and it's a constant 600 +/- you should be able to just use it right?

 

[Jacob32123]

Okay guys this might be the random idea of the week...

Let's say I have one that gives 4.2 V at 600 mAh and the termials are easy to connect and get a + and - out of. Could I power a heatsinkined 445 or a 635nm with it and make a lab style build that runs of wall curent? I mean provided you check the current and make sure there are no spikes beforehand and it's a constant 600 +/- you should be able to just use it right?

mAh are the number of milliamps a battery can supply for an hour. mA are a measure of current. Do you mean 4.2v at 600ma?

 

[joeyss]

Yea I meant current.

 

[dieselmarine]

I wouldn't try that personally..probably ruin the diode with a spike.. if there is no protection.

 

[rocket689]

Watch with "wall warts".

Their labelled voltage and current are notoriously wayyy out of spec.
Plus they may have voltage/current spikes.

I wouldn't do it unless you are ready to kill a diode with a slim chance of survival...

 

[joeyss]

I had a digital muiltmeter hooked up to one and it stayed constant (both the current and the voltage)..after all they do seem to have some voltage and current regulator. I even was able to charge 2 NimH D cells by hooking them up to a smaller 3.0V battery charger. I just timed it based on the ma. I mean diodes can be quite fussy , but those 445s seem rather tough..., but I dunno if spending $40+ is worth the risk. If I was gonna risk it I'd rather chance maybe a $10 red diode with the smaller charger.

 

[Cyparagon]

A multimeter is not fast enough to detect spikes. It will only give you the average.

 

[DrSid]

You need current source. This sounds more like voltage source. Such source will increase current to meet output voltage under load. Sure .. those diodes can handle about 2A .. which is most likely more than the source can provide. Also if the source will be set at 4.2V, it should be on the lower side of working voltage of the diode. Still it's risky.

 

[LarryDFW]

joeyss;

I have operated a 445nm off a 4.2 VDC switching supply with no problems.

Carefully check the voltage without a load to insure it is not over 4.3 VDC.

Also, make sure the laser diode is on a good heat sink, so overheating is not a problem.

I do prefer 18650 lithium ion cells for their portability.

The red 635nm diode would need a regulator to lower the voltage.

LarryDFW

 

[joeyss]

Hey thanks for the info...does anyone know if resistors would simply work for diodes provided you have a off switch and secure the connection before turning it on? I have a 4 AAA battery pack and a 4 AA pack. Would that work? I've heard about voltage spikes in batteries , but provided I use a resistor that gives me maybe only 400ma at around 5 volts would that work? I'm talking about 445s

 

[DrSid]

You can rather safely use 3 AA or AAA batteries and no resistor. The voltage is just right. If you use non rechargeable batteries, there should be no spikes. At least I have direct drive laser which I use for some months without any problem.

 

[joeyss]

So just put one that has zero volts and is dead for the 4th battery then?

 

[DrSid]

Nah, dead battery usually has high resistance. Just short circuit the fourth slot with bolt or roll of aluminum foil or something ..

But as it is winter .. ie dry air .. ie high surface charges .. pay SPECIAL attention to electrostatic discharge.