SSC P4 direct drive question

evh · Jun 21, 2007

Hi guys. I have a 17670 that's about 5 months old and fresh off the charger at 4.17 V. I connected it to a SSC P4 direct drive and only got a current draw of 700 mA. I read somewhere in this forum that it's supposed to drive a SSC P4 at around 1 Amp. Any ideas what went wrong? Could the SSC P4 be on it's last legs?

hburner · Jun 21, 2007

It could just be that certain emiiter is only going to pull the 700 in direct drive. Nothing wrong with the emitter.

I have had different lux's that pulled different currents out of the same bin codes, as much as 150mAh. hb.

Randy Shackleford · Jun 21, 2007

Do you know the Vf of the emitter?

evh · Jun 21, 2007

I'm afraid I don't know the Vf. The SSC was salvaged from a cheap flashlight. It was running on 6 volts with resistor. I can't remember how much resistance though.

EngrPaul · Jun 21, 2007

Is the SSC in a host or bare? Hopefully it has an outlet for heat! :tinfoil:

RV7 · Jun 21, 2007

I once tried direct drive a SSC without resistor from a 18650, which has similar characteristics as a 17670. The current draw was 1.5A when the battery was full at 4.2V. Still over 1A at 3.85V. So either you got a SSC with an extraordinary Vf or the battery is dying, or both. You can find out by measuring the battery voltage under load.

jsr · Jun 21, 2007

It could also be your ammeter is contributing more resistance than you think. If possible, try switching the ammeter to a higher measuring range. You give up resolution for more accuracy due to a lower value internal resistor.

evh · Jun 21, 2007

Thanks guys for the suggestions.

EngrPaul: The SSC is on an old aluminium heatsink I took from an old PC. Thanks for the concern though.

RV7: I'll measure the Voltage under load when soon.

jsr: I'm using a multimeter that is set on 10A resolution.

evh · Jun 21, 2007

RV7: The battery's voltage under load is 3.7 V. Fresh off the charger, the voltage was 4.17 V.

RV7 · Jun 21, 2007

3.7V at 700mA for an SSC doesn't sound too high.

10A range is fine considering it's in series with the LED.

The internal resistance of a healthy 17670 should be below 0.2 ohm. So at 700mA the output voltage drop should be less than 0.15V. If you measure the open circuit voltage of your battery now and get a reading higher than 3.85V, then the battery is aged, or has experienced over charge/discharge many times.

evh · Jun 22, 2007

Thanks for the help guys. :twothumbs

I'll try and get another battery and SSC to pinpoint the problem.

FlashKat · Jun 22, 2007

EngrPaul can give you the best advice, since was the GURU of modding SSC P4 Seoul flashlights.

evh said:
Thanks guys for the suggestions.

EngrPaul: The SSC is on an old aluminium heatsink I took from an old PC. Thanks for the concern though.

RV7: I'll measure the Voltage under load when soon.

jsr: I'm using a multimeter that is set on 10A resolution.

SSC P4 direct drive question

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