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07-11-2010, 02:04 AM #1
 Class 2M Laser Join Date: Aug 2009 Posts: 690 Rep Power: 20
Tabish
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Voltage / current draw

What voltage would a 140 be running at if the micro boost is set to 1A.

Need to know because I want to calculate the current draw at battery so I can estimate battery life.

EDIT:

So assuming the diode uses 4.4V @ 1A and the driver efficiency is 80%:

Its pulling 5.5W from the battery. Which means a current draw from battery of:

-1.31A when fully charged (4.2V)
-1.49A nominal voltage (3.7V)
-1.83A when discharged (3.0V)

The battery is a 14500 about 900mAh with a discharge rating of 1.5C.
This means a safe discharge of about 1.35A.

If I keep a short duty cycle, it should be able to get at least 30 min of run time right ?

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Last edited by Tabish; 07-11-2010 at 04:52 AM.

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07-11-2010, 03:08 AM #2
 Class 3B Laser Join Date: Dec 2009 Posts: 3,175 Rep Power: 264
BShanahan14rulz
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Re: Voltage / current draw

Calculate how much power your laser diode uses (power out) using its Vf at the current you desire and the current.
P=I*V

(Power in)*(driver inefficiency %) = power out
or
Power in = (power out)/(driver inefficiency %)

driver inefficiency you should use the lowest % stated on the datasheet of your driver.

Once you know how much power needs to be drawn from the battery, you can figure out, using P=I*V, what current will be drawn from the battery at a given voltage. As your volts drop, your current draw will increase.

Now go out and catch some fish

07-11-2010, 03:42 AM #3
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laser_freak
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Re: Voltage / current draw

I don't have my 445nm build up and running yet (waiting on some AixiZ modules), but here is some data from other people.

Lasersbee's data:
a140: 1050mA --- 4.34V
a140: 960mA ---- 4.31V
a130: 1090mA -- 4.79V

Exerd's data:
a1?0: 1000mA -- 4.5V
a1?0: 1000mA -- 4.6V

Hemlock_Mike's data:
a1?0: 1000 mA -- 4.25V

ff-racer's data
a1?0: 1000mA -- 4.24V

Hope this helps.

Last edited by laser_freak; 07-11-2010 at 03:46 AM.

07-11-2010, 04:24 AM #4
 Class 2M Laser Join Date: Aug 2009 Posts: 690 Rep Power: 20
Tabish
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Re: Voltage / current draw

Quote:
 Originally Posted by BShanahan14rulz Calculate how much power your laser diode uses (power out) using its Vf at the current you desire and the current. P=I*V (Power in)*(driver inefficiency %) = power out or Power in = (power out)/(driver inefficiency %) driver inefficiency you should use the lowest % stated on the datasheet of your driver. Once you know how much power needs to be drawn from the battery, you can figure out, using P=I*V, what current will be drawn from the battery at a given voltage. As your volts drop, your current draw will increase. Now go out and catch some fish
Yup I know that. What is the Vf for a 140 at 1A though ?

EDIT:

Quote:
 Originally Posted by laser_freak I don't have my 445nm build up and running yet (waiting on some AixiZ modules), but here is some data from other people. Lasersbee's data: a140: 1050mA --- 4.34V a140: 960mA ---- 4.31V a130: 1090mA -- 4.79V Exerd's data: a1?0: 1000mA -- 4.5V a1?0: 1000mA -- 4.6V Hemlock_Mike's data: a1?0: 1000 mA -- 4.25V ff-racer's data a1?0: 1000mA -- 4.24V Hope this helps.
Thanks. I'll just assume 4.4v then.
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