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07-09-2008, 05:32 AM #1
 Class 3R Laser Join Date: Sep 2007 Location: California Posts: 1,127 Rep Power: 159
ixfd64
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how is battery life calculated?

Does anyone know how to calculate how long will a set of batteries last?

At first, it seemed that this was done by simply dividing the mAh rating by the current draw. However, something doesn't quite add up. For example, the current draw of Wicked's green pen-style lasers is 600 mA, so a set of two batteries should last over three hours, assuming that each battery has a capacity of 1,000 mAh. However, Wicked lists the battery life as 90 minutes.

Am I missing something?

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07-09-2008, 05:37 AM #2
 Class 3R Laser Join Date: Apr 2008 Location: South Florida Posts: 1,544 Rep Power: 134
Jimmymcjimthejim
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Re: how is battery life calculated?

Yes, as you have read in other threads and whatnot, most drivers (including the one in your laser) aren't 100% efficient. So all that power going into the laser, only some of it goes into the diode. I believe that readings from the multimeter show the current going into the diode, not the total current used.
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Current Lasers:
8??nm: 1050mA DIY Micro Sized
658nm: 2mW keychain pointer - DIY 80mA/350mA switchable in Altoids tin - 300mA DIY Micro Sized
632.8nm: 10mW Hughes HeNe - 15mW Melles Griot HeNe - 1mW Melles Griot bare tube
612nm: 5mW Meredith Instruments HeNe
594.1nm: 4mW Meredith Instruments HeNe
543nm: 2mW Melles Griot HeNe - <1mW Multimode 6" HeNe (He's cute!)
532nm: 5mW Lyra-G5 - 70mW DIY by Wannaburn
473nm: 5mW Lab Style
445nm: DIY 650mA in Sonar II Host
405nm: DIY LG 10X at 330mA with Ehgemus host and Microboost - CNI GLP-405 70mW

07-09-2008, 11:04 AM #3
 Class 4 Laser Join Date: May 2007 Location: Queensland, AU Posts: 7,549 Rep Power: 689
Things
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Re: how is battery life calculated?

Batteries arent always up to spec, in fact, they rarely are!

07-09-2008, 12:38 PM #4
 Class 2M Laser Join Date: Nov 2007 Location: United Kingdom Posts: 529 Rep Power: 31
Helioplasma
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Re: how is battery life calculated?

Battery mAh divided by the draining current in mA = possible turned &quot;on&quot; in hours
i.e [s]WL[/s] executives : power consumption : 600mA ; average AAAs : 900mAh ; battaery lifetime = 900/600 = 1.5 = 1h30.
of course batts will never ever last 90 minutes in a green laser pointer so maybe I've been tricked by WL.
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95mW infiniti - TO OLD !!! Hardly burns anything without good batteries. But nice as a pointer. Looking at NOVA lasers currently for a fresh new one.
125mW pulsar - Piece of 54!T, doesn't do anything. No burning power at all. But very beautiful as a laser pointer.
191mW ++ IgorT Romisen/CREE laser - This really kills your eyes (without goggles).
170-180mW LikeItBright Ultrafire laser - Works like a flashlight, but a beast up close.
200mW + LCC in police host By Moh. Nice red, and very cheap.
550mW Yobresal "Tiny Laser" - Incredible beam. This specific wavelength isn't really comfortable for the eyes though.
NOIR laser goggles OD 7+ for 180-534 nm Oemlasersystems

Other lasers not worth mentioning
TOTAL AMOUNT SPENT ON LASERS = 1065 \$ AT LEAST (not much compared to some other people here...)
Always look on the bright side of lasers ------------------- not literally

07-09-2008, 04:50 PM #5
 Class 3R Laser Join Date: Apr 2008 Location: South Florida Posts: 1,544 Rep Power: 134
Jimmymcjimthejim
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Re: how is battery life calculated?

Quote:
 Originally Posted by ixfd64 Does anyone know how to calculate how long will a set of batteries last? At first, it seemed that this was done by simply dividing the mAh rating by the current draw. However, something doesn't quite add up. For example, the current draw of Wicked's green pen-style lasers is 600 mA, so a set of two batteries should last over three hours, assuming that each battery has a capacity of 1,000 mAh. However, Wicked lists the battery life as 90 minutes. Am I missing something?
Oh and I missed something that I caught in Helioplasma's post.. The batteries are connected in series, which adds the voltage rather than the current. So if you have two 1000mAh batteries in series, then the batteries together have a capacity of 1000mAh, but with 3v instead of 1.5v.
__________________
Current Lasers:
8??nm: 1050mA DIY Micro Sized
658nm: 2mW keychain pointer - DIY 80mA/350mA switchable in Altoids tin - 300mA DIY Micro Sized
632.8nm: 10mW Hughes HeNe - 15mW Melles Griot HeNe - 1mW Melles Griot bare tube
612nm: 5mW Meredith Instruments HeNe
594.1nm: 4mW Meredith Instruments HeNe
543nm: 2mW Melles Griot HeNe - <1mW Multimode 6" HeNe (He's cute!)
532nm: 5mW Lyra-G5 - 70mW DIY by Wannaburn
473nm: 5mW Lab Style
445nm: DIY 650mA in Sonar II Host
405nm: DIY LG 10X at 330mA with Ehgemus host and Microboost - CNI GLP-405 70mW

07-09-2008, 09:52 PM #6
 Class 4 Laser Join Date: Jun 2007 Location: Carbondale, IL Posts: 5,254 Rep Power: 755
styropyro
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Re: how is battery life calculated?

Quote:
 Originally Posted by Jimmymcjimthejim Yes, as you have read in other threads and whatnot, most drivers (including the one in your laser) aren't 100% efficient. So all that power going into the laser, only some of it goes into the diode. I believe that readings from the multimeter show the current going into the diode, not the total current used.
Efficiency of the laser has nothing to do with the current drawn, when you measure the total current draw of the laser by putting the multimeter leads in the tail cap and battery you get the total current being drawn, not just the current going into the laser diode. So if your laser draws 600mA and you have 900mAh batteries in series, the battery life of the laser will be 1.5 hours pretending the batteries don't sag under the high current draw. Of course that never happens so the battery life where the laser is actually useful and not dim/mode hopping is usually a lot lower.
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07-09-2008, 10:37 PM #7
 Class 3R Laser Join Date: Apr 2008 Location: South Florida Posts: 1,544 Rep Power: 134
Jimmymcjimthejim
Class 3R Laser

Join Date: Apr 2008
Location: South Florida
Posts: 1,544
Rep Power: 134
Re: how is battery life calculated?

Quote:
 Originally Posted by styropyro [quote author=Jimmymcjimthejim link=1215581533/0#1 date=1215581837]Yes, as you have read in other threads and whatnot, most drivers (including the one in your laser) aren't 100% efficient. So all that power going into the laser, only some of it goes into the diode. I believe that readings from the multimeter show the current going into the diode, not the total current used.
Efficiency of the laser has nothing to do with the current drawn, when you measure the total current draw of the laser by putting the multimeter leads in the tail cap and battery you get the total current being drawn, not just the current going into the laser diode. So if your laser draws 600mA and you have 900mAh batteries in series, the battery life of the laser will be 1.5 hours pretending the batteries don't sag under the high current draw. Of course that never happens so the battery life where the laser is actually useful and not dim/mode hopping is usually a lot lower.[/quote]

Oh, thanks for correcting me
__________________
Current Lasers:
8??nm: 1050mA DIY Micro Sized
658nm: 2mW keychain pointer - DIY 80mA/350mA switchable in Altoids tin - 300mA DIY Micro Sized
632.8nm: 10mW Hughes HeNe - 15mW Melles Griot HeNe - 1mW Melles Griot bare tube
612nm: 5mW Meredith Instruments HeNe
594.1nm: 4mW Meredith Instruments HeNe
543nm: 2mW Melles Griot HeNe - <1mW Multimode 6" HeNe (He's cute!)
532nm: 5mW Lyra-G5 - 70mW DIY by Wannaburn
473nm: 5mW Lab Style
445nm: DIY 650mA in Sonar II Host
405nm: DIY LG 10X at 330mA with Ehgemus host and Microboost - CNI GLP-405 70mW

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