I have a 3D MagLite, many years ago I modded it with a good heat sink and a Seoul P7 based off something I saw on CPF. There is no driver, it is directly driven. I have been trying to get an understanding of current replacements. Will the SST40 be capable of being driven from 3 D cells, I may use Nimh cells? I believe amps is fine, but what about 4.5 volts. PS I’m new to this and did read up on the LED sticky, I just can’t figure if the SST40 can take 4.5 volts.
frazlabs uses the sst40 in their lights, it’s direct drive with a single Liion. you should be ok with 3×NiMH
Is it difficult for you to change the LED or easy going?
I ask that because the SST40-Class of LEDs aren’t that expensive, so you could just try it.
Cheapest at Convoy:
SST-40: LUMINUS SST40 LED - Convoy flashlight
Or what about a LMP LED? THe LHP73B has a regular max- current of 20A - your Setup won’t even come close to that
Only Problem is, that the LHP73B and LHP531 have quite low Vf.
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Thank you both! I am going to give one a try. I don’t think it will be difficult to get it in there. I appreciate the feedback.
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Shouldn’t be a problem in this scenario because (1) NiMH cells are significantly lower than 1.5V, and is on average 1.2V during discharge, and (2) NiMH AA’s have significant internal resistance, which causes the output voltage to sag. A decent high-power LED like SST40 or LHP531 is in no danger, provided that heatsinking is adequate.
I would recommend against the SST40–low CRI, ugly tint. Try SFT40 in 3000K for a high-CRI incan-like beam, 5000K for a neutral thrower, or LHP531 for a very efficient flooder with nice tint.
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Thank you. Yes I am going for the high CRI version.
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Nimh are capable of high currents, especially D, you may burn up your sst 40, with fresh cells current may go well above 5A, as far as 4,5V (i assume you mean alkaline cells) they will not provide current that would be dangerous to the led, never mind voltage, it will sag under load anyway, your led will never see 4.5v.
Old p7 leds were higher voltage than modern leds it was safe to drive them directly from 1 li ion, or 3x nimh, new leds with 3v or lower will pull a lot of current from those cells.
Thank you for this, indeed I think I did burn up my LED using the NiMH cells, but I have another LED. Will a 3v/8A buck driver be suitable for this arrangement?
Max current according to the datasheet is 6A, driving at 8A is between overdrive with limited lifespan, or burning it depending on how good you remove the heat. but I would not even drive it at 6A TBH. I’d limit to 5 max, there will not be much noticeable decrease in brightness, If you had leds directly soldered to a copper water line with no stars, then maybe you could run at 8A, but in case of maglite, I would not, unless you want to change leds more often than overdriven bulbs.
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