Power supply requirements for 2X MUBM44 diodes?

Inspired by the Belphegor build I am considering the first step in a much more elaborate Wizards Staff build.

Am I correct that I would need a modified 4D maglite and 4X 32650 batteries to power the 2 NUBM44 diodes?

Will I need a 5-Cell Maglite to fit the longer batteries?

If using a SXD drivers set at 4.5 amps a NUBM44 will draw 3 amps at 8 volts ( 2 cells ) or 2 amps each at 12 volts ( 3 cells )

So 2 x NUBM44's with SXD's at 4.5a each would only draw 4 amps if your battery supply was 3 x 26650 IMR cells and slightly more as they discharge.

A 4 C-cell Maglite would hold 3 x 26650's with a spacer, a round wood dowel cut to fit with a brass paper fastener through a center hole could be used.

Your 26650's will need to be low resistance high drain IMR or INR such as EFest or Basen, I have tested these and 3 in series with SXD drivers they will carry 2 NUBM44's no problem. You will have 34 watts of waste heat to deal with.





I just got some Basen cells recently and they hold over 4 volts from a full charge into a 1 ohm load at 3.8 - 3.9 amps for a 30 second test as do the EFest, I also run NUBM44's all the time on 2 EFest 26650's for several minutes at a time until the large heat sinks are hot, and after cooling for several minutes more, I recharge 2 cell units when the cells are down to 3.7 because the SXD drop out is 6.8 volts, but running 3 cells I can wait until each cell is down to 3.3 - 3.4 volts before I recharge and that's after many multi minute runs.

It's 24 watts into the SXD and 22.5 watts out and into the NUBM44 that put out 7 watts. So roughly 17 watts of waste heat per diode.

RedCowboy said:

If using a SXD drivers set at 4.5 amps a NUBM44 will draw 3 amps at 8 volts ( 2 cells ) or 2 amps each at 12 volts ( 3 cells )

So 2 x NUBM44's with SXD's at 4.5a each would only draw 4 amps if your battery supply was 3 x 26650 IMR cells and slightly more as they discharge.

A 4 C-cell Maglite would hold 3 x 26650's with a spacer, a round wood dowel cut to fit with a brass paper fastener through a center hole could be used.

Your 26650's will need to be low resistance high drain IMR or INR such as EFest or Basen, I have tested these and 3 in series with SXD drivers they will carry 2 NUBM44's no problem. You will have 34 watts of waste heat to deal with.

I just got some Basen cells recently and they hold over 4 volts from a full charge into a 1 ohm load at 3.8 - 3.9 amps for a 30 second test as do the EFest, I also run NUBM44's all the time on 2 EFest 26650's for several minutes at a time until the large heat sinks are hot, and after cooling for several minutes more, I recharge 2 cell units when the cells are down to 3.7 because the SXD drop out is 6.8 amps, but running 3 cells I can wait until each cell is down to 3.3 - 3.4 volts before I recharge and that's after many multi minute runs.

It's 24 watts into the SXD and 22.5 watts out and into the NUBM44 that put out 7 watts. So roughly 17 watts of waste heat per diode.

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Thanks, this is exactly the info I was looking for.

Would I be right in assuming that a 3 D cell maglite would work for this project if the tailcap was modified as outlined in jayrobs maglite kit thread *link*

Are these Feilong 32650 *link* just not up to the task (not low enough resistance, not good enough quality?) compared to the 26650s you recommend?

They look like regular Li-ion and have no specs telling of internal resistance or maximum sustained output and maximum surge output.

There are 8000 mAh 26650's but typically the higher the capacity the higher the resistance and why this matters is because of the voltage sag.

The EFest 4200mAh stay above 4 volts into 1 ohm for 30 seconds but the blue wrapper 8000mAh 26650's drop below 3.5 volts into 1 ohm imediatley, both from a full charge.

The reason this matters is because the bucking drivers have a minimum input voltage and higher resistance cells will sag more as they discharge and not maintain minimum input voltage as long as a lower capacity rated cell with a higher sustained output.

I have seen people use the feilong 32650's but not for 2 x 7 watt diodes, also they are not IMR or INR formulation, that is a better formulation for high drain low sag, the reason 18650 and 26650 chemistry has evolved where the 32650 seems to be lagging behind and have few options is because of the vape market needing high drain cells and the RC market has rectangle cells tuned to suite their needs, you could use a 10,000 mAh RC battery pack but not in a flashlight host.

Anyone who has tested the feilong 32650 can chime in, they look like just larger, more expensive old technology cells.

RedCowboy said:

They look like regular Li-ion and have no specs telling of internal resistance or maximum sustained output and maximum surge output.

There are 8000 mAh 26650's but typically the higher the capacity the higher the resistance and why this matters is because of the voltage sag.

The EFest 4200mAh stay above 4 volts into 1 ohm for 30 seconds but the blue wrapper 8000mAh 26650's drop below 3.5 volts into 1 ohm imediatley, both from a full charge.

The reason this matters is because the bucking drivers have a minimum input voltage and higher resistance cells will sag more as they discharge and not maintain minimum input voltage as long as a lower capacity rated cell with a higher sustained output.

I have seen people use the feilong 32650's but not for 2 x 7 watt diodes, also they are not IMR or INR formulation, that is a better formulation for high drain low sag, the reason 18650 and 26650 chemistry has evolved where the 32650 seems to be lagging behind and have few options is because of the vape market needing high drain cells and the RC market has rectangle cells tuned to suite their needs, you could use a 10,000 mAh RC battery pack but not in a flashlight host.

Anyone who has tested the feilong 32650 can chime in, they look like just larger, more expensive old technology cells.

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jayrob offers 32650s for use in the maglite hosts he sells, that is the only real reason I was considering them.

I also came to the same conclusion that 32650s were lagging behind the others. Maybe that will change in the near future and IMR/INR, protected and cells with better than 6000mAh with low resistance will come to market.

In the mean time I'll plan on using the EFest 4200mAh till something better comes out and is vetted.

I have not tested the fielong 36650's, their size may make up for a lot, from a cost point they may not fair.

The cheap ultrafires can drop like a stone when under load, and IMR/INR will sag less than the old gold standard Panasonic 18650B, but if he has a set up with those large cells ask him how they test out, you can also use his host and a pvc sleeve and buy twice as many quality 26650's for the same price, but I have not tested the feilong 36650 so I don't know how well they hold up, 6000mAh is a conservative number for a cell that large, they could avoid sag pretty well, if they were rated 12000 mAh then I would say they would sag.
I know people use them, I would like to see the 36650 in IMR formulation, but like I noticed 6000mAh is a conservative number so ask him before I talk you out of them.

RedCowboy said:

I have not tested the fielong 36650's, their size may make up for a lot, from a cost point they may not fair.

The cheap ultrafires can drop like a stone when under load, and IMR/INR will sag less than the old gold standard Panasonic 18650B, but if he has a set up with those large cells ask him how they test out, you can also use his host and a pvc sleeve and buy twice as many quality 26650's for the same price, but I have not tested the feilong 36650 so I don't know how well they hold up, 6000mAh is a conservative number for a cell that large, they could avoid sag pretty well, if they were rated 12000 mAh then I would say they would sag.
I know people use them, I would like to see the 36650 in IMR formulation, but like I noticed 6000mAh is a conservative number so ask him before I talk you out of them.

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jayrob sale: 6000mAh 32650 Li-Ion Batteries

Colonel Sanders said:

Jay, you'll be pleased to know that these cells have not only passed my tests, they've far surpassed my best hopes. I'm going to start a thread in the battery section over at the mother site but I'll at least give a quick summary here. I'll also post a link here when that thread goes up for those who want the nitty gritty details. Here are the discharge data summary...

Discharge rate/Mah
2 amp = 5580
4 amp = 5559
5 amp = 5501
10 amp = 5384!

These cells hold up under load like nothing else I've tested. They very easily bested a brand new MNKE IMR26650 which made 3784Mah at 10a draw. The Feilong ran much cooler, longer, and suffered from far less voltage sag overall. That's saying something as the now discontinued MNKE IMR26650 cells are excellent. That's a difference of over 42% Mah at a 10a load in favor of the Feilong cell and that's not counting the lessened voltage sag which means the difference in actually energy supplied is even greater.

... P.S. I will be ordering more of these cells. I have several 26650s which are about to get replaced in my D Mags.

Man are these some awesome cells. I can't believe I haven't heard more about them.

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