Driver problem with non-constant decreasing current

[kmm5117]

So I have run into this driver problem more than once, and its really starting to bug me.

When I build high powered lasers, generally I prefer an X-Drive, but as we all know they aren't really possible to find (please let me know if you have a source!).

Anyways I was messing around with two drivers today, both an pre-set BenBoost mini as well and a FlexDrive. Like I said the ben boost is pre-set, but I can't remember the current, something fairly high. The FlexDrive I have a solder jumper on the highest setting (theoretically should go to 1.5A).

On both drivers when I get up my test load (for a 445nm diode), I get a current reading initially (around 800mA for both), but the current constantly drops and never levels off. The flexdrive will provide a stable reading if I turn the pot lower, about 700mA is the highest I can get it before it starts acting strange. Both drivers are heatsinked in the appropriate places, and I'm using a single 3.7V Li-Ion. Now the drivers get warm, but nothing incredible, i'm only running them for less than a minute.

Can anyone help me with this strange activity? I know its not the driver, this is happening with all of my BenBoosts and FlexDrives, an X-Drive, any linear, or some generic drivers seem to work fine. Also this is doing the same thing at high currents on a MicroBoost.

Thanks much in return

 

[BShanahan14rulz]

Measure the voltage on your 18650 while it is powering the test load via one of those drivers. I bet you have a bad battery.

Your test load, the diodes aren't overheating, are they? Can you touch them wihtout getting instant burns? Test loads are so simple they rarely fail, but if it happens with all your drivers, it has to be battery or test load, eh?

 

[Wolfman29]

To echo Shanahan, it definitely sounds like it's your battery.

 

[kmm5117]

My test load diodes are can get warm/hot, but not enough to burn me. Also, what voltage should I expect the battery while under a load, the normal 3.7-4.2V?

 

[AnthoT]

My test load diodes are can get warm/hot, but not enough to burn me. Also, what voltage should I expect the battery while under a load, the normal 3.7-4.2V?

What kind of battery? Some are better than others and for those boost drivers at 1.5 amps you will need a decent one.

 

[The Lightning Stalker]

You have to start swapping/eliminating components. Try eliminating the battery and powering
from the wall. Try a different load. A 1Ω resistor works or an LED or different diode. At this
point what the load actually is doesn't matter.