Advice for a 6xNUBM44 build?

Sta said:

Thanks, contacted him. Do you know if the batteries I referenced will be enough even for a full NUBM06 block?

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That depends on what you're gunna run the diodes at, as well as if the battery specifications are completely accurate.

30c is the multiplier, and the capacity is 6200mAh.

30c*6.2Ah = 186Ah

Theoretically the battery could be drawn up to 186A for a short burst, and as the amperage draw declines then the run time increases.

Let's say you're running your diodes at 4.5A each. 4.5A*8(8 diodes) = 36A

6.2Ah/36A = 0.17h

.17*60 = 10.2
.17 hours is 10.2 minutes

So you could run 8 diodes running at 4.5A for 10 minutes. Keep in mind this is only if the battery specifications are completely accurate. Hopefully I did all my math correctly as well, if I messed up anywhere let me know.

If your using SXD drivers they cut off at 6.8v and batteries sag under load, the SXD can take 16v so I would go with higher voltage packs and IMR or INR formulation if your using 8 drivers.

You could wire them in series and use a 4.5 amp regulated supply, you will need 40 volts or so.

A dc to dc can be found on ebay, but think about ramp up and you don't want any spikes so I would use a dedicated supply, not a variable.

Cheaper drivers can be found on ebay as well.

I might go with 8 Chinese drivers because the ramp up and protections are already designed in, or consult my power expert and build one, but ramp up and clean spike free power is important with laser diodes. High efficiency is less heat to get rid of as well.

Thanks for your help. For a higher voltage battery pack, what about this one?
http://www.ebay.com/itm/2x-3S-10000...855143?hash=item25b786ce67:g:3hQAAOSwDuJW1DVe

Sta said:

Thanks, this is quite useful. Do you know of any higher-capacity 7.4V lipos or are 2 of these my best best?

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No problem.

For sure, here's one: Maxamps LiPo 22 000 mAh 7S 25 9V 40C Battery Pack Popular for UAV Applications | eBay

I'm guessing you don't want to dish out all that money for a battery though, so it's really just a matter of looking around. You'll definitely find higher capacity 7.4v batteries around here and there, but it's up to you to find the best price to capacity battery. The one you listed in the OP should do quite well though, but if it's run time you're looking for you should check out the prices of higher cap batteries.

If I use 2 x 26650 my draw is 3 amps. But with 3 cells it's 2 amps.

My nubm44 with 3 x 26650's draws 2 amps into the driver at full charge so if you used 8 SXD drivers I would figure 2.5 amps each so yea, 20 amps draw is about right at 11.1 volts for 8 diodes with some drop and discharge.

Will those put out 10 amps each constant? I don't see it in the specs.

If you parallel the batteries you need 20 amps constant output at 10 volts. The SXD is 95% efficient and your diodes need 22.5 watts each so yea, 200 watts out of the batteries.

I would use a dozen Efest IMR 26650's in 4 strings of 3 but as long as those will put out 10 amps constant they should work.

It's better to go a little bigger than you need, and as they discharge and voltage drops current will be higher.
Also the higher the mAh the more drop under load.........those may not be big enough, the wires look too small.

RedCowboy said:

My nubm44 with 3 x 26650's draws 2 amps into the driver at full charge so if you used 8 SXD drivers I would figure 2.5 amps each so yea, 20 amps draw is about right at 11.1 volts for 8 diodes with some drop and discharge.

Will those put out 10 amps each constant? I don't see it in the specs.

If you parallel the batteries you need 20 amps constant output at 10 volts. The SXD is 95% efficient and your diodes need 22.5 each so yea, 200 watts out of the batteries.

I would use a dozen Efest IMR 26650's in 4 strings of 3 but as long as those will put out 10 amps constant they should work.

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222W going into 8 diodes/drivers? That's crazy to think about and also a ton of power :thinking:

RCB if you're talking about the new batteries that Sta posted - they'll do 10A for an hour constantly @11.1v if it's specs are accurate, and it can do a ton more current the lower run time you go because of it's 25c capability.

10 amp hours is fine as long as they will put out 10 amps each without dropping under 9.5 volts.

That's not in the rating.

My NUBM44 takes 24 watts into the driver and puts 22.5 watts into the diode that puts 6.5 watts out, then the lens eat some and I set a bag on fire at 20 feet, but it takes 24 watts per driver/diode, the NUBM06 will be a little less but not much.

Batteries sag under load, 20 amps at 10 volts is what he needs and batteries sag.

I use 3 x 26650 that are 4200mAh and rated 20a costant and 50a surge and they wear down, 2 cells need a charge after 5 minutes running 1 NUBM44 or they sag below 6.8 and these are IMR good cells. With 3 cells I get 3 or 4 sessions of 4-5 minutes and a mass of aluminum is warm after each run.

Maybe I run a little longer than 5 minutes, in the winter I can go twice as long, maybe 2 cells do 3 minutes times 3, but they are not dead, I have to stay above 6.8v under load.