Hi there i have a led panel with 2 parallel streams of 5 leds in series each.

When i am using the led driver / dimmer that was originally with the specific led panel from a 7,4 battey it gives 15,5 volts to the leds that under this voltage draw 0,85 A.

Bypassing the driver and using a bench power supply @ 15.5 v directly to the leds, the current draw does not exceed 0.61A while even if i increas to 16,5V the current does not increase over 0.7A (the power supply can give up to 5 Amps)

What i am not understanding?

 

Hello,

Wich chip is used in the led driver?
That way you could possibly retrieve the schematic.
The voltage you are reading from the led driver is an avarage voltage.
The peak voltage will be much higher, leading to the higher current.

Bertus

 

The original led driver has no data (the only chips that are identifiable are stp60n06-14, Lm 358 which are probably regulating/ boosting power since is has a 6-17v input- and a TL4946 which is a PWM control for dimming (am i correct)???

All the voltages i mention are voltages measured / logged for 15 minutes or more...
I had the impression that under the same voltage i would expect the same current draw...

 

There is some missing information but I'll make some assumptions and just give some "generic" information..

LEDs are current driven devices and need to be fed from a constant current power supply and not a constant voltage power supply..
They are NOT light a lightbulb or other resistive device. They are diodes and function differently..

You should not be concerning yourself with the voltage and should set your benchtop supply to constant current mode (if it has one) and set the output current to .85A (if thats really what your LEDs need)
It will adjust voltage as needed to achieve a fixed .85A

 

@mcgyvr (by the way i love your nickname, it was my nickname too when we were kids )) ) Please tell me what else is needed...

I am setting voltage according to the constant current (so the power supply is in cc mode).
I have tried yesterday again and in order to achive 0,85A draw the voltage reached 16.7V (5 leds in series so 3.3+V and 0.85/2A -2 strips in parallel).

The original led controller that came with the specific led (pwm controlled) managed to light the leds under 0.85A current draw with 15.5V...

Why i can not have the 0.85A at 15.5 as the original circuit and i am forced to drive them at 16.7 to achive it?
These panels will be lit continously for several hours, would the excess voltage harm them?
I do not know the specs of the specific leds but based on the original driver i can assume 0.4-0.5A at 3.1V

 

variations in measurement tools... different Vf depending on temperature,etc... different constant current circuit in the driver vs your power supply.. Some have more of an voltage drop related to the power supply than others..

If you are giving it 850mA and thats what it was designed for then you are good to go.. The voltage is just what it is..

 

A couple of possibilities:

What current are you measuring with the battery and driver? If you are measuring the current from the battery? This will be different than the current through the LEDs.

Does the driver possibly have a PWM output? This would affect the current you would read with a multimeter.

Show us exactly how things are connected and where the measurements are taken.

Bob

 

I am measuring the current that flows through the leds (just before the leds - after every circuit).

The driver is PWM controlled but it seems on the oscillator (a cheap one though) almost a flat line...

I am attaching a drawing. Regards




sorry i can not rotate it