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Ok, hold on. I was under the impression you just needed to drop a bit of the 37V to below the led's rating of 36V and then vary the brightness from there. Although you did say vary current as well, but I assumed varying brightness is the end game.The current is the problem I need to reduce the current will the 0.2 ohm 15 w resistor in series be enough to drop the current 2 amps as I keep destroying the led lightes.
Thank you
Doesn't quite answer my questions but lets work with what you've given. And you've already got a PWM controller for brightness as well, I presume you're already using this Si14HyATPC1-50V-20A for dimming?Information about the project.
The battery is 10/ 3.7 volt lithium polymer cells (battery space supplied) rated 37volts 6.5 amp hr with a 30 amp max draw.
High Power Li-Ion Battery: 37V 6.4Ah (8048168-5C, 236 Wh, 30A rate)
Controller is the 50 volt model Si14HyATPC1-50V-20A Adjustable Ramp-Time
Led are rated 30 - 36 volt 9 amp
Cable is approx 1metre, cable is rated 16 amp 600v.
Higher voltage would maybe 2/ 37 volt batteries
Have larger canister to accomodate them.
Remember we are underwater using wet connectors!!!!
If you go to this web address you will find the controller that is being used and specks.
**broken link removed**.
If that's salt water, things could get interesting . Methinks the connectors wouldl have a short life.Remember we are underwater using wet connectors!!!!
Remember we are underwater using wet connectors!!!!
If that's salt water, things could get interesting . Methinks the connectors wouldl have a short life.
What you are saying is to put a .5 ome 40 wat resist in series on the output side of the controller
I thought Gregory said his max input voltage was 39V. Either way, I explained all the steps and results with regards to HIS specs and he could easily go through it again with a higher max input voltage.No.
Your operating conditions vary to widely to be able to do adequate current control with pure resistance. Your battery voltage will be as high as 42 on peak charge (unless you never run the LEDs while charging) down to 30Volts at the low end of the charge cycle. As such, the voltage dropped across your resistor varies from zeroV to 6V. With a half ohm resistor, your current will range from zero to 12 Amps. And it won't max out at 40 Watts. Even if the LED forward voltage stayed at 36, you could have as much as 72 watts. But led voltages decline with temperature. I don't know the exact ratio for your LEDs, but let's suppose 2V. You now have a 8 volts across your half ohm resistor giving 16 amps of LED current and dissipating 128 watts in the resistor.
If you had a higher input voltage you could get away with a linear control circuit, or a buck only switcher. But with the varying voltage that you have, about the only practical choice you have is a buck/boost switcher that provides some intelligent control to compensate for the operating variables.