Shark Buck

[mudman cj]

cfive-1: I did not mean to run the LED DD without the circuit in between. 4.8V is too much without the circuit (never mind 5.4V! :green🙂, but with the circuit then there is a voltage reduction to the LED which leaves about 3.5V left at the LED given 4.8V into the circuit.

 

[cfive-1]

mudman cj, I do not run DD that wos only short testing.Still looking for a driver which can give regulated output 2.8A at input voltage 4.4V-5.4V.

 

[Techjunkie]

Hi mudman cj
Thank you for your replay(I think it's meant for me).I tested my batteries in DD input 4.1V output 2.3A at 3.5V at P7 LED.At input 5.4V(fully charged) output 7.5A(I stoped after few seconds).I did not test yet at 4.8V.
Regards cfive-1.

Out of curiosity, were you able to measure the voltage drop of the four NiMH D under the 7.5A load? I'm contemplating direct driving a 9A SST-90 from four D NiMH (AccuPower LSD cells) if they'll sag low enough to not drive the SST90 over 9A...

 

[cfive-1]

Techjunkie
Test was-4xfrash charged NiMh 12000mAh Titanium PowPower.No load voltage 5.6V.
DD a P7 Bin C (other data unknown) for 5-7 seconds,current through LED 7.5A and stedy.I did not measure batt.voltage under load(voltage drop),I have only one tester and can not measure 2 values at a time.
Sorry I am afraid to repiet test it could burn LED.
Regards cfive-1.

 

[Frankie02]

Hey Wayne

I was wonderin' if I could use Assembled SHARK with Remora to drive my P7 "J" with 9AA to 3D holder..would it be enough to last for awhile or do I need to change the power source to different kind of battery ?

 

[dat2zip]

Hey Wayne

I was wonderin' if I could use Assembled SHARK with Remora to drive my P7 "J" with 9AA to 3D holder..would it be enough to last for awhile or do I need to change the power source to different kind of battery ?

You can run the P7 from 8 to 12 AA battery configuration.

I'm sure others have more info on configurations that they have done.

Wayne

 

[Frankie02]

You can run the P7 from 8 to 12 AA battery configuration.

I'm sure others have more info on configurations that they have done.

Wayne

which one is best for my mod ? Shark Buck or Blue Shark ?

 

[darkzero]

Any ETA on the SharkBucks?

 

[Aircraft800]

Wayne,

With the new Cree XM-L LED's with low fv, is it possible to run 3X XM-L with 3X 17670 Li-Ion's, or is that too close to the Buck Sharks limits? I know 4 Li-Ion would be a better combination, but I don't know of any 4S 18650 adapters for dual boared Mags, but there are plentyful 3X 17670 adapters 🙂

 

[dat2zip]

Three LEDs with Vf of 3V is 9V in total.

Remember take your batteries low and high Voltage. For a fresh li-ion that would be 4.2V and I don't know where you consider discharge is, but, let's say 2.5V.

For three batteries that would be 7.5V to 12.6V.

In order for the Shark buck to be in regulation all the time the complete battery range must be higher with margin in order to maintain regulation.

Since 9V is not always less than 7.5V - 12.6V this situation is not optimum for full regulation all the time.

It may be in regulation under fresh batteries conditions, but, will fall out of regulation at some point in time before the batteries are fully depleted.

To determine a different configuration determine the following:

1) sum up the Vf of all the series LEDs.

2) Based on the battery technology and number of batteries determine the low and high battery voltage.

3) For a boost the low and high must be less than the sum of Vf. For a buck the low and high must always be higher than the sum of Vfs.

Wayne

 

[Aircraft800]

Once it drops out of regulation, does the shark buck direct drive and operate normally? If the overhead is not so high, low vf XM-L string might say in regulation till the batteries are 3.2v per cell, and are just about depleted anyway (3v correct?).

Sent from my PC36100 using Tapatalk

 

[dat2zip]

Yes, the Shark Buck drops out of regulation and goes into DD.

Wayne

 

[Lumencraft (Matt)]

With a shark buck once the voltage drops near the VF of the LED does it cut the power off, or will it go to DD?

 

[dat2zip]

With a shark buck once the voltage drops near the VF of the LED does it cut the power off, or will it go to DD?

It drops into DD.

 

[Darkstang]

New member here but have done a lot of reading and searching on the Shark Buck. What is the typical overhead that the sharkbuck needs in highpower useage?

I am interested in driving several Xm-l in series from a automotive setup. My supply is 14.3v that seems to be decently regulated. I know I will still need to add an inline regulator setup to the power for protection of the Shark setup.

With a vf of 3.35 volts at 3 amps for the xml, that puts me around 10 volts for 3 Xm-l's. This leaves 4.3 for the Shark to dissipate out in the form of heat. My concern is when turned down to lower settings when supposedly the xm-l's vf drops as low as 2.8-2.9. This could leave a ceiling of over slightly 5 volts. Is this too much?

4 xm-l's would be at 3.35 would only give a ceiling of about 1 volt and I believe from some of your replies, that may be too little.

Airflow and heatsinking are not a concern since it will have lots of airflow and can be hooked to good sized sinks.

Would like to use a shark buck if I can in this situation to make it simple. Also thought about doing the poor mans multi lux setup as well.

 

[videoman]

I wish to drive a single XM-L led with the Shark buck 3A, the battery voltage is either going to be 6 volts or 12 volts DC. If I use the 12V source, will the driver get hotter as opposed to using a 6 V source ? Does it also mean that it wastes the excess voltage in heat, introducing the possibility of thermal shutdown as opposed to using 6V ?

 

[Justin Case]

The Shark Buck is a buck driver (hence the name), not a linear regulator.

 

[videoman]

About the heat thing ?

 

[cmacclel]

About the heat thing ?

It's a real driver so heat should not be an issue.

Mac

 

[Justin Case]

The Shark Buck is a buck driver. The driver "bucks" down Vin to match Vout by adjusting its duty cycle. It isn't a linear regulator that burns up the excess voltage as heat.