Linear Driver Problem?

Ok, so I recently purchased a Mohgasm 1.25A driver. As i was waiting for a diode, I decided to check the voltage output of the driver. I put in 2 cr123's for about 8.4v input, and out came 7.8 volts. Wouldn't this kill my diode? I was worried because I am pretty cash strapped and don't want to blow my diode. I hooked it up to a test load using 1n5404's, and just to see the input it still was 7.8 volts into the test load. So is something wrong with the driver or what.


Thanks

How much current were you seeing across your test load? You have to remember, the driver is going to try and raise the voltage as much as it can until it puts out the right amount of current.
If the test load isn't trying to draw 1.25A, the driver is going to be putting out as much voltage as it can to try to make it.

So I measured the current across the resistor, and got a very weird number. The driver was outputting 660 mA. It should be around 1250 mA. So now I am thinking that the batteries cannot supply the 1250 mA.

Can you take a picture or a video while testing ?
That would help us a lot.

Jim

It sounds like it's running fine, your just likely using too many diodes in your test load. To simulate a 445 diode you should be using 5 or 6 diodes in series.

The fact that it's only putting out 660mA is the reason the voltage is so high.

You have to think how constant current drivers work. They want to output whatever current they're set to output.. So they'll float the voltage to whatever is needed until the load draws that amount of current. Your linear driver with 2 li-ions will only put out 7.8V maximum.. however your test load is only drawing 660mA at that voltage. If your driver could put out more voltage with this combo, it would, since it's trying to get the voltage up to the point your load draws 1.25A

Yes, Qumefox i think you are probably right. The diode came in and i wired it up and it lased just fine. Also, i realized i was using 1n4001 diodes for my test load, i realized it when they were getting pretty hot.

Thanks.