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Laser Power And Amps

BrilliantLasers

BrilliantLasers

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Apr 11, 2019
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There are a few things I am confused about when it comes to giving power to a laser power supply. What happens if a battery is hooked up to a laser power supply, and the amp rating on the battery is higher than the power supply requires? In this case, I have a battery that is 6 amps, and the power supply is rated for 3amps. Will the power supply only draw the 3 amps, or will it take in the full 6amps and potentially damage the power supply or diode?

Sorry if I sound a little newbish, but it's hard to find a straight answer sometimes.
 





The driver will pull whatever current it needs as long as the battery is able to supply it.

Also, are you sure that battery is rated in amps and not amp hours?
 
diachi said:
The driver will pull whatever current it needs as long as the battery is able to supply it.

Also, are you sure that battery is rated in amps and not amp hours?
Click to expand...

Actually yes, you are correct on that. It does say 6000 mAH. Is there a way to know what the amps are from amp hours?
 
6000mAh is the capacity, it means 6 amps for 1 hour which would also do 3 amps for 2 hours or 1 amp for 6 hours but NOT 360 amps for 1 minute, it's not really linear because you will likely get 1 amp for a little more than 6 hours and if you could get 360 amps for a second before it burst into smoke and possibly flames you would only get it for a quick second if at all.

For instance a good 3.7v Li IMR formulated cell may be rated 4200mAh and say 20a/50a which is 4.2a for 1 hour and it will put out 20a for a minute or so and 50a for a few seconds at a time which is what the ratings are all about, they are made mostly for the vape market so we benefit with a high drain capable cell.

However you should not plan to power a 20a load with this, that's a short burst rating, 4200mAh as a guild suggests around 4 amps as your max sustained load however it varies, it's best to use more battery than you need and they will last longer, that is cycle " charge and discharge " for a longer lifespan if not stressed to the max.

Something I look at is how much a battery sags under load, if it drops more than 10% under load I am not happy.

p.s. Your driver will draw the current/amps it needs, what you want is to make sure your battery voltage is within the drivers input range and that your battery is up to your task as explained above.

A bucking driver won't need as much battery capacity if you are putting in more voltage than you are getting out, remember volts x amps = watts so you need to look at the watts out and watts in because if you are using a boost driver that puts out a higher voltage than you put in you will need more battery capacity.

---edit---

What driver/laser do you have ?

If your driver is putting out 3a @ 5v and is a boost driver you will need a healthy battery as it will need to put out over 3a probably closer to 5a and you can't trust the Chinese ratings especially of the cheap cells, if it's a buck driver then any good pair of cells should do fine.

As too your original question a battery puts out voltage and the capacity is how much current is available as rated over time, you wont hurt it with too big of a battery as long as your voltage is correct/within spec, in short more mAh just means it will run longer.
 
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A battery doesn't really output voltage as "voltage" is just a potential difference between two points and exists in the absence of current flow. An analogy would be the flow of water through pipes. The voltage is the water pressure and the current the the amount of water flowing through the pipe.
 
Electricity doesn't actually flow through a wire like water, in reality electrons jumps from atom to atom, this is why atoms with less electrons in the outer orbit are conductors and atoms with their outer orbit full are insulators.
 
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I believe what you're asking is if your load will pull it's desired current or if it will pull the full capacity of the power source's discharge current. Provided that the load is not a short circuit, it will pull whatever current it needs without damage as long as the source has the correct voltage.

Talking about discharge ratings, if I'm not mistaken it's generally accepted that all max li-ion discharge rates are at least 1C, where C is the capacity and what you are calculating is maximum rated discharge. For example a 3Ah battery would be able to be discharge at 3A without an issue (1C, or 1*3Ah). If you need higher than that you should check the battery specs, some batteries are high discharge (up to 30C), li-po batteries usually have high discharge rates for example.
 
if you have 6000mah 18650 baterry lithium,it is poor quantity ,you can buy a samsung,panasonic,.... real baterry,

I know that's not what you want to ask, but I think you should know
 
Hello,

I think the Problem is relativ simple.
For example, you will drive a laser Diode with 1 Watt power Output. The Efficiency of your Diode is 33,3 %. So you need 3 W to drive your laser.
On the other side, you have your non linear laser Driver with an Efficiency of 90 %. So your Batterie must Support the System with 3.7 W.
With an Lithium Batterie, approx. 4V you will have a current of 0,93 A. Thats it.
If you look for the Efficiency of laser diodes, have a look at the DTR site. You will find a lot of measurements with laser power in W, Voltage and Ampere of the power supply.


best regards

Edgar
 
RedCowboy said:
Electricity doesn't actually flow through a wire like water, in reality electrons jumps from atom to atom, this is why atoms with less electrons in the outer orbit are conductors and atoms with their outer orbit full are insulators.
Click to expand...

No. That is why I called it an analogy.
 
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