Need advice on how to power my newest mag project.

DKlaser

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So I have all the stuff on the way to build a D sized mag using a SST-90 emitter and the 9a driver sold by DW that can be viewed here...

http://www.candlepowerforums.com/vb...icient-5A-9A-Buck-Converter-for-SST-50-SST-90

and

http://daoriginal.da.funpic.de//data/Buck%20Converter/powerbuck/powerbuck_1_0.pdf

Specs are...

- High efficiency ( 94% - 98%)
- Input voltage range: 6V-22V
- Output current: fixed to 9A
- The input voltage must be at least 2V higher than the output voltage, otherwise output current will get lower.
- 1mm² silicone wires preinstalled


Ok so I am wanting to put this in a preferable 2D mag but the largest I would want is a 3D. What would you guys suggest I use to power this thing? And what would be a guesstimate run time for your suggestions.

Also, what wire do you guys suggest using and can the stock mag switch handle this?
 
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nein166

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Re: Need advide on how to power my newest mag project.

I'd suggest using 2 IMR 26650 cells with a 1" PVC tube spacer in the 2D - de-anodize the inside of the tailcap and put a spring in there you may need a spring in the front too there are no button tops on the IMR 26650 cells

Definately replace the stock maglite switch I know someone has a "how to" for a rocker switch that can handle 10A search for it
 

DKlaser

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Are there no IMR cells in the 32650 size? I am very familiar with the tail cap mod I just had to do it for my XML build that used a pair of 32650 cells.

Are those cells you suggested a protected type cell? Can you provide a link to a good set of them? Also what kind of runtime do you think I can get?
 

Justin Case

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Re: Need advide on how to power my newest mag project.

I would use 3xIMR26500 in a 2D to drop the battery current draw to a level that the Mag switch can manage. Assuming that the claimed driver efficiency is accurate, 3xLi-ion should result in a current draw of less than 3A, while delivering the 9A drive current to the SST-90. A D Mag switch can certainly handle that current.

I'd probably use a minimum of 20 gauge wire between the driver and the SST-90.

For calculated run time, the SST-90 draws around 33W (9A, 3.6V). 3xIMR26500 are nominally about 25Wh. So you might get about 30-45 min run time.
 

vestureofblood

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Re: Need advide on how to power my newest mag project.

Are there no IMR cells in the 32650 size? I am very familiar with the tail cap mod I just had to do it for my XML build that used a pair of 32650 cells.

Are those cells you suggested a protected type cell? Can you provide a link to a good set of them? Also what kind of runtime do you think I can get?

You dont necessarily have to use IMR cells in this build. Here are some D cell size li-ion. If you use a pair of these they can easily handle the load. A pair of these will easily fit a 2 D mag. There is also a protected version sold by the same website.

The true capacity of those cells is closer to 4500 ma from what I have read, so your runtime would be ROUGHLY an hour, although actually draining the cells to the cut off point is a bad idea.
 

willieschmidt

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Re: Need advide on how to power my newest mag project.

I have a different spin.... Tabbed NiMH AA Tenergy 2300ma homemade packs in a Mag 3D. Running 6Sx2P it's possible to get 7.2v@ 4400ma. The real beauty is the source is on the Bay (no link but easy to find) that has the cells @ .42 each (48@$20 delivered). Works out to 4 packs at $5 each. Is this the mod, think outside the box, DIY kind of place isn't it? FET switch. 18ga teflon wire.
 
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DKlaser

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Re: Need advide on how to power my newest mag project.

I for sure need protected cells as I do not want to purchase another device to turn off the light when the voltage is too low. I would really like to use the stock switch if at all possible... Especially when this light can drain a set of cells so quickly. I really like the idea of sticking with a 2D light so I want the best setup for that host.

What about these cells, can they handle this job?

http://www.novaeproducts.com/apps/webstore/products/show/1846436
 

willieschmidt

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Re: Need advide on how to power my newest mag project.

Jayrob used those cells (w/ tail cap mod) and the same driver a while back on a PT54 based light. I don't "Mr Google cut and paste" so search away. Your stock switch will work.
 

DKlaser

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Re: Need advide on how to power my newest mag project.

I am a completely in the dark about cells, amps, current, max discharge rate and pretty much anything else electric. I can put anything together if someone tells me what to use.

I just did a 2D build using these cells and a tail cap mod but it is not this powerful. So I have no clue if they will hold up for this project. I need very clear anwsers for most any of the questiosn I ask because I just do not know what some of this stuff means.
 

willieschmidt

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Re: Need advide on how to power my newest mag project.

I am a completely in the dark about cells, amps, current, max discharge rate and pretty much anything else electric. I can put anything together if someone tells me what to use.

I just did a 2D build using these cells and a tail cap mod but it is not this powerful. So I have no clue if they will hold up for this project. I need very clear anwsers for most any of the questiosn I ask because I just do not know what some of this stuff means.

sst-90 with those cell, that driver, proper heat sink, reflector and lens, you should be able to shine like the sunrise. it will keep you warm and toasty on winter nights. keep everything in moderation if you want long run times. this place is a regular cornucopia of knowledge and information, just search and you will find the answers.
 

vestureofblood

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Re: Need advide on how to power my newest mag project.

Hey man dont worry, we got your back.

Not one of us was born knowing these things.

The short answer to your question about those cells is NO.

Normally I would say yes but unless there is a GROSS error on the cell data those cells can only be discharged at 2500-3000ma.

In most cases li-ion can be discharged at a rate of "2C" this means 2x capacity. HOWEVER those cells you linked say "Discharge rate: 0.4-0.6C" This means they can only handle a load of roughly half the 5500ma capacity.

Unless you can find conclusive data from a reliable source like a CPF member with some real world discharge testing on those exact cells, I would not recommend it. At the very least you run the risk of damage to the cell if not worse.

Another very real problem you may run into trying to go with a protected cell is that many of the protected cells will not allow you to discharge the cell at above 3 amps.

If you really want a protected cell 4sevens has protected cells that are proven to work at a 5 amp discharge rate.
http://www.4sevens.com/product_info.php?cPath=53_57&products_id=2585

Using 2 of these cells would give about 50 min or so of runtime.

Here is a fairly simple way to get a ROUGH idea of your run time with a given cell.

Because the VF (voltage forward) required by the LED is close the the same voltage provided by a single li-ion we can look at it like this. You need 9000ma to power your light. Each cell has a capacity of 3900ma so divide 3900ma by 9000ma and you get .4333 That means you would get .4333% of an hours runtime. Now since you are going to use 2 cells we can double that to .86 Then .86 x 60 minutes = 51.6 minutes run time.

Remember this is a VERY loose translation of how run time is calculated and it only works because the voltage required by your LED is so close to the voltage provided by the battery.

If you decide you want to know the formula for getting a much more precise measure I will give it but I'm not going to spend the time elaborating on the long version unless you are sure your ready.
 
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DKlaser

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Re: Need advide on how to power my newest mag project.

Thanks for the info, it helps. Another forum member "Jayrob" that I would say is also a pretty sharp guy uses these cells to power a PT54 based light using the same driver. More info can be found on that build here...

http://laserpointerforums.com/f42/9-amp-pt-54-phlatlight-maglite-mod-64054.html

What are my other options if I do not go with a protected cell? I guess I could be talked out of them but how am I supposed to tell when they are discharged to the point that I need to pull them out and no over discharge them? I hear it is really bad to over discharge these.
 

zelda

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Re: Need advide on how to power my newest mag project.

I recently built a SST-90 Mag with the 9A-Driver and two 32900 Li-Fe.
Thats around 6V under load, its not enough for the driver!
The input should be at least 2V higher, in my case its more.
 

DKlaser

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Re: Need advide on how to power my newest mag project.

Isn't the rated voltage for a Li-Fe cell only like 3.2v? What kind of voltage is it reading fully charged? The Li-ion cells are reading right at 4.2 fully charged. Do you think they have enough to drive the sst-90?
 

vestureofblood

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Re: Need advide on how to power my newest mag project.

Going with unprotected cells is not that big of a deal as long as this light is not something others can "get a hold of". Provided you or someone educated in Li-ion safety are the only users of the light it shouldn't be an issue.

Using a quality charger will take care of the over charge problem. A smart charger will automatically cut off at 4.2V.

To keep from over discharge your first line of defense is having your estimated run time. Next with that driver when you hit the 6V mark you will probly see a noticeable drop in output, so using 2 li-ion 6V is a good stopping point anyway.

With li-ion after use of the light for more than a few minutes its best to go ahead and top off the cells anyway. This is better for the cells than leaving them in a state of discharge and protects against accidental over discharge.
 

willieschmidt

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Re: Need advide on how to power my newest mag project.

Thanks for the info, it helps. Another forum member "Jayrob" that I would say is also a pretty sharp guy uses these cells to power a PT54 based light using the same driver. More info can be found on that build here...

http://laserpointerforums.com/f42/9-amp-pt-54-phlatlight-maglite-mod-64054.html

What are my other options if I do not go with a protected cell? I guess I could be talked out of them but how am I supposed to tell when they are discharged to the point that I need to pull them out and no over discharge them? I hear it is really bad to over discharge these.
If you are dead set on using a 2D mag you are limiting your capacity. Your DW driver will handle the extra battery of a 3D Mag and should make a better running light. I am a keep it simple type of guy. Run my red PT54 direct drive @ 8a+ and my green PT120 DD @ 25a+. Lion are good but not always the best. I use NiMH in those applications. Wouldn't suggest anything that I didn't believe in. That is why the tabbed AA were mentioned above. I have some on the way. Best of luck.
 

Justin Case

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Re: Need advide on how to power my newest mag project.

What are my other options if I do not go with a protected cell? I guess I could be talked out of them but how am I supposed to tell when they are discharged to the point that I need to pull them out and no over discharge them? I hear it is really bad to over discharge these.

Depending on a cell's protection circuit to prevent overdischarge is not a good way to go. Those devices are best considered as secondary protection. They usually trip at a very low voltage already, e.g., 2.7V or even less. Better to pay attention to how long you've run your light relative to a conservative estimate of total available run time, and also note if you see any drop in output that indicates the cells are just about depleted.
 

Justin Case

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Re: Need advide on how to power my newest mag project.

If you are dead set on using a 2D mag you are limiting your capacity. Your DW driver will handle the extra battery of a 3D Mag and should make a better running light.

The 2D Mag size is far more convenient than 3D IMO. Fits a lot better in cargo pants pockets for example for utility use.

3xIMR26500 is a very simple mod to power a 2D Mag. See here for the PVC conduit that one can use for a spacer and what to use to de-anodize the tail cap to drop down the tail spring.

Building your own 6S2P NiMH pack using tabbed cells is a nice way to go as well, and cheaper than the IMRs, but IMO is slightly more complex. Also, my guess is that the OP will need a charging solution for that pack.
 

DKlaser

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Re: Need advide on how to power my newest mag project.

Ok, I think I have narrowed it down to a couple options both use a 2D mag. I have also decided that the run time does not need to be an hour I can settle for 30 minutes roughly. I already have a nice light that I just finished that will go for 3 hours+ with a 1000 lumen output. This light is more for the wow factor. I know its not a real "WOW" light but to my folks and friends it will be. Hell the 1000 lumen light they are already highly impressed with. To me the smaller the light the more wow factor is has. People just in general would expect a longer flashlight to perform better just from their own reasoning. We all know that is not the case but the masses tend to think "bigger is better" So this is a factor for me wanting to stay with 2D size.

Help me decide...

Option 1) Go with 8, IMR 14500 cells that require a special holder made by fivemega that will put 8 cells in the 2D body. The body will need to be machined out and I will have to buy the holder and 8 cells. This configuration will give 14.8v (3.7v each) and 4800mah total. (cells are only 600 mah each) Guesstimate on run time on this setup?

Option 2) Go with 3 of the IMR 26500 cells that will just require a spacer sleeve (that I can make at work) Do a tail cap mod that I can also do at work and just buying the 3 cells. I already have a charger that will work for any of these builds. This setup will give about 6900 mah. Guesstimate run time on this setup?


Just for kicks Option 3) Go with 4, IMR14500 cells for a voltage of 14.8 with a total mah of 2400, get it cut down to a 1D size, and buy the holder from fivemega. Would I even get 10 minutes of runtime with this setup? This option has the best cool factor to me as it will pack a major punch for being so small.


That being said why can I not use li-ion IRC14500 cells that have a mah of 1200? will they not handle the discharge rate this light is gong to require?
 
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vestureofblood

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Re: Need advide on how to power my newest mag project.

Wow dude, LOL it seems like we have come a great distance from your original plan, but here goes :)

Option one. To me this seems like a waste of time and money. Buying a $50 battery holder. Having to bore out the mag body. The additional time and effort it takes to charge all of those cells to keep a balanced pack. All this to power only a single LED?

#2 This is by far the best of the 3 options. Simple and effective.

To get a quick run time estimate we can grossly oversimplify the proceess in this case by saying 3 cells give 2300ma each combined total of 6900ma possible divided by the 9000ma needed gives .76 hours runtime.

That is still less than what using only the 2D cells from KD would provide but you would have a better quality cells using AW IMR 26500s, and you would have a broader range of cell type to use in future lights.

#3 Same thing 2400/9000= .26 hours runtime.

I am not sure what IRC means, but if you are referring to standard li-ion cells a build like this would be very hard on the cells.


Its nice to see you have/are being diligent about learning the best option before spending money or taking a risk by "just tryin' stuff"
 
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