22mm Convoy 6v/8.25A driver mod

[Amak87]

I have a 22mm 6V/8.25A convoy driver that that I would like to reduce the current from 8.25 to 6-6.5A. I’m trying to make a driver that will push the NUBMOF and Osram PLPT9-450LB_E 8W diodes to their respective limits.

This driver works the same as the other 22mm 6V/5A Convoy drivers, as it has temp control and 12 groups to choose power levels.

I know I can add a resistor or diode in series on the negative line, after the diode, I’m just trying to figure out what’s the best option to get 6A, 6.25A, and/or 6.5A.

Any help? Ideally I’d like to precisely reduce the current by 2A. But I don’t have a ton of resistors on hand so that’s why I’m trying to find out the options.

Here are pictures of the driver.

 

[Z80 Lasers]

Replace the resistor on the negative output with a higher value and it should drop the current.

 

[Amak87]

Replace the resistor on the negative output with a higher value and it should drop the current.

View attachment 78254

perfect! Cuz I actually already removed it and I’m just trying to figure out the proper SMD resistor to solder in its place? I tested the driver using a Samsung 40T battery and it puts out 6.2V at 7.93A. Would an R200 resistor work to get me to 6.2A?

 

[Amak87]

Replace the resistor on the negative output with a higher value and it should drop the current.

View attachment 78254

Also, the other 22mm Convoy 6V/5A driver uses a R010 resistor, I’m thinking of using a resistor that’s between these? Something in the range of R008-R007?

 

[Amak87]

Replace the resistor on the negative output with a higher value and it should drop the current.

View attachment 78254

So do you think the R010 resistor would get me 6A?

 

[Ricker]

Do you have a breadboard to plug everything into and test different resistors with a test load and dmm? I would just answer you but I don't know for sure what the value of the resistor would have to be

 

[paul1598419]

perfect! Cuz I actually already removed it and I’m just trying to figure out the proper SMD resistor to solder in its place? I tested the driver using a Samsung 40T battery and it puts out 6.2V at 7.93A. Would an R200 resistor work to get me to 6.2A?

I would use a dummy, or test, load to set the current.

 

[Amak87]

I have a test load setup, that’s not the issue. I’m just going to throw a R010 on and see where it lands me. The R010 is used on the other 22mm 6V/5A convoy drivers, so I’ll use an Osram 450LB_E to test it with the R010

 

[Amak87]

Do you have a breadboard to plug everything into and test different resistors with a test load and dmm? I would just answer you but I don't know for sure what the value of the resistor would have to be

I don’t think a breadboard would really help me at all, considering I have to solder the resistor before the negative lead on the driver… it would probably create a lot more work, if it would even be plausible

 

[Z80 Lasers]

One of the problems is that more power is being pushed through these tiny components than what they are rated for. As heat increases the resistance gets lower so you have to factor that in a bit. One way to help mitigate this issue somewhat is by stacking resistors in parallel of twice the value of what you're looking for. Also, when dealing with resistance values this low the actual impedance tends to vary from resistor to resistor. You're going to have to play around a bit until it's in a suitable range for you.