Hi guys.


I have a 445nm build using a single 18650, the current is set to 1A , the microboost gets very hot very quickly...and after 30 seconds, starts pulsing...any ideas why? do i need to limit current going IN to the microboost?

TIA

How do you have it wired?

What is the brand and mAh rating of the battery?

That pulsing is usually a power supply problem

Peace,
dave

Its inside one of jayrobs 18650 hosts.. the battery im not sure about, it came out of a laptop battery pack, but that same battery performs flawlessley in my 290mw 532 for as long as i ask it too. And tbh, i think the pulsing is the mmicroboost overheating and shutting down.

It is not the driver. It is the poor quality battery. Your battery will work at high currents with the green because the pump diode is low voltage. The combination of high current and higher voltage is overtaxing the battery. Replace your battery with a high quality battery.

Peace,
dave

Im unconvinced haha, i'll test it on my bench supply, btw im not going against you, you have way more experience than me, the reason im saying i think its the driver, is simply the temperature it reaches in less than 30 seconds..im suprised the components havent desoldered themselves haha. But like i say, i have a good quality lab bench supply so i'll give it a run on that.

By chance have you measured the temp of your Mircoboost at 30sec?

Ped ---
I had that problem too haha... Mine wasn't the battery either though yours might be haha..... I didn't have the power input connected to a proper ground as the instructions require. I felt really stupid haha when I realized that the driver is not common ground.
In aluminum housings, it is hard to get a reliable ground. That's why I use that "spare" connection on the 445 diode as case ground. It's press fit and will handle the current back to the neg input.
I have been there because I didn't read all the paperwork haha........

HMike

How do you have the diode connected to the MicroBoost?

You cannot connect the case pin to the diode - output pad on the driver like you can with the Flex.
As Mike says, connect the case pin to the - driver input.

Yup, like this:

Photo by Ehgemus

It's the battery. Make sure it's a quality lithium ion. Of course this has already been stated but I had a pulsing output with a battery problem.

Ok i'll connect the case pin to the NEG input, and test/replace the batt, i'll report back.

Following the advice given, could one of the boffins check these items out, this is what ive orderd and let me know if thier ok?

TRUSTFIRE BATTERY CHARGER FOR 18650 14500 CR123A & MORE on eBay (end time 07-Sep-10 14:52:45 BST)


ULTRAFIRE 18650 BATTERIES X 2 RECHARGEABLE PROTECTED on eBay (end time 29-Aug-10 13:07:25 BST)

The pulsing is usually caused by the battery voltage dropping below the input threshold. It can also be caused by voltage drops across all of the small resistancs in the circuit such as metal-to-metal contacts. The biggest culprit I've found is those cheap clicky switches. Use an accurate Ohmmeter and measure across all these points - when you find the culprit, it will be obvious. Try the clicky switch first. Bet you that's the problem.

Dave

One of the things you can do to improve efficiency in high current builds like this with the microboost is to solder two one-ohm resistors in parallel with the large range resistor, turn the potentiometer all the way down, and re-set the current to 1A with a dummy load. This will relieve the circuit of 250mW heat, and it will also use a little less juice from your battery and require a little less voltage from it, too

QUOTE=drlava;815038]One of the things you can do to improve efficiency in high current builds like this with the microboost is to solder two one-ohm resistors in parallel with the large range resistor, turn the potentiometer all the way down, and re-set the current to 1A with a dummy load. This will relieve the circuit of 250mW heat, and it will also use a little less juice from your battery and require a little less voltage from it, too [/QUOTE]

I agree.... EXCELLENT IDEA!!!
Lots of smarts on this forum... that's 4 sure !

I solved the problem this way Mini Quick & dirty TUT. Pulsing Flex/Boost driver? Read in.

However the 2 resistors trick will be getting tried on my next build


I now have a duty cycle of around four mins