What is the voltage input on MC-E if wired 2s2P and Direct Drive?????

Hi all,

I know MC-E Wired 2s2P with 1.4A driver takes 8V~13V input or so I think.

But, if I dont use a driver and just do DD does that mean the voltage input is 3V~9V or so?


Thanks,
bigC

2S2P would be double the voltage of 4P, Around 7.2v?

think2x said:

2S2P would be double the voltage of 4P, Around 7.2v?

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That is awesome. Thanks for the confirmation. My idea is simple. A twistie super skinny and short 4Sevens Quart mini DD with MC-E 2s2P and powered by 14500 cells or a Peak solutions Brass bezel/body 2*AAA body with MC-E 2s2P and powered by 10440 cells.

bigC

forward voltage for 350mA (per P, 700mA Total) will be (per datasheet)
Typical: 6.4V
But it could be lower
or it could be as high as 7.8V

forward voltage for 700mA (per P, 1400mA Total) will be (per datasheet)
Typical: 6.8V
But it could be lower
Or it could be higher

Scientifically, that literally is as close as you can plan it.. And you had better hope that the 4 die are well matched.

You would be much better served by running them in 4S1P and using a proper driver (probably boost mode, if you're planning on two cells)

LEDs are really poor candidates for Direct Drive, and they are also really poor candidates for Resistor Current Limiting. They're dynamic loads (based upon temperature and age) and they are not precision values (each LED WILL have a different Vf from the next one).

LEDs need an active circuit, be it an SMPS or a Current based Linear Regulator..

Ben

The datasheet spec is 3.5V at 700mA drive. Thus, 2S2P would be 7.0V at 1.4A drive. In reality, I'd say Vf will be closer to 6.6V. Thus, you will probably overdrive a 2S2P MC-E using 2x14500 in direct drive and also probably be over the usual 2C discharge limit for a LiCo-based cell such as an AW14500.

AW10440 unprotected cells are rated at 340mAh. I don't know what the exact discharge curve of a 10440 cell looks like under various loads, but I would think that such small cells would not be happy trying to direct drive a 2S2P MC-E at full power.

Justin Case said:

The datasheet spec is 3.5V at 700mA drive. Thus, 2S2P would be 7.0V at 1.4A drive. In reality, I'd say Vf will be closer to 6.6V. Thus, you will probably overdrive a 2S2P MC-E using 2x14500 in direct drive and also probably be over the usual 2C discharge limit for a LiCo-based cell such as an AW14500.

AW10440 unprotected cells are rated at 340mAh. I don't know what the exact discharge curve of a 10440 cell looks like under various loads, but I would think that such small cells would not be happy trying to direct drive a 2S2P MC-E at full power.

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Good point Justin.

I will stick with a Mini 2*AA as a host. That way I know the IMR 14500 red coat cells can take the 8~plus watts an MC-E 2s2P can dish out. Maybe a resistor in the tailcap to compensate for the voltage input. Or something like that.

bigC