Rechargeable Batteries Weak?

• Feb 17, 2012

• #1

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Hello, I've purchased my first laser some days ago and I noticed something strange.
At first I tought the laser was broken, because I put two AAA rechargeable batteries and it didn't work, but then I found some alkaline batteries and it worked.
The laser is this one: Rayfoss.
The thing is, I've got some Uniross 900mAh AAA batteries and the power output seems much much lower than with the alkaline batteries, despit the voltage being HIGHER (according to my thrusty multimeter).
The alkalines im using measure at about 1.38v each and the rechargeable at about 1.4-1.42.

So are rechargeable batteries not really an option for me?

Regards

PS: Is there any way to see if I really have 50mW power without a meter?

 

• Feb 17, 2012

• #2

lasersbee

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Alkaline batteries are 1.5V each... Rechargable AAA are 1.2V each.
With 2 Batteries that is a difference of 0.6Volts...
Your problem is VOLTAGE not Capacity...

As to the Power question..... No....


Jerry

 

Last edited: Feb 17, 2012

• Feb 17, 2012

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Actually as I said in my topic the rechargeable batteries measure 1.4-1.42 volts, and the alkaline only 1.36-1.38.

 

• Feb 17, 2012

• #4

Tech_Junkie

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Rechargeables sag a lot faster than Alkalines. They may top off at 1.4, but they quickly drop down to ~1.2

 

• Feb 17, 2012

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Tech_Junkie said:

Rechargeables sag a lot faster than Alkalines. They may top off at 1.4, but they quickly drop down to ~1.2

Click to expand...

I find it very strange I mean, I measure the batteries in the meter the combined voltage of the two is 2.8 volts and the dot is so much weaker than the alkalines which measure 2.6v combined...
Maybe under a load the rechargeables voltage drops?

 

• Feb 17, 2012

• #6

lasersbee

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Did you check the voltage of your batteries under load...:thinking:
If not your voltage measurements are useless...

Open circuit voltages of batteries is not a good indicator
of actual under load voltages..


Jerry

 

• Feb 17, 2012

• #7

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I tried to check under load but I can't figure out how to.
Where should I connect the multimeter probes to check it?

 

• Feb 17, 2012

• #8

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Exactly. Car batteries work the same way. They can be putting out 12v solid, but put a load on it and it will drop to a point it wont start the car.

EDIT. Just add the meter to the circuit loop.

 

Last edited: Feb 17, 2012

• Feb 17, 2012

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The thing is the positive is facing the bottom of the case and I don't know how to connect it to the loop. Sorry I don't have much experience with electronics.

 

• Feb 17, 2012

• #10

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Connect the batteries together, then put a wire on the + and clip it to the case, then put one end of the meter probe on the - side of the battery, and clip the other probe on the spring inside the head of the laser.

Turn the laser on and take a reading.

Or maybe Lasersbee has a better way.

 

• Feb 17, 2012

• #11

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Won't that connect the - from the battery to the - on the laser?
How will that measure the battery voltage?

 

• Feb 17, 2012

• #12

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I figured out how to do it but I dont have any electrical wire ATM, will try it later.
However, has anyone else felt this issue?
What are the best batteries that I can use for my 3v laser?

Regards

 

• Feb 17, 2012

• #13

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Alkalines. Or you can get a 3.7v 10440 lithium rechargeable battery, and charger. Then you'll need a spacer to to take the place of the missing battery.

These are the reason I dont like pen lasers. You're better off getting a torch or tactical laser. Like this Rayfoss. The batteries these lasers use are common in other lasers, so if you're getting into the hobby its a better buying choice.