Best driver for XRE on Ds?

CPF,

So you may be able to tell if you look at some of my threads in the homemade section but after a few years of flashlightholism, I have decided to try building some stuff myself. I have some XP Gs on the way for an Ammo cabinet I want to light Up and I also got my Maratac AAA ripped apart awaiting an XP G. This brings me to the 3rd and last project Im going to do all at once to form my first projects.

This is what I want to do. Im looking to run a 3D maglite on Tenergy NiMh's. The LED im going to use is a XR-E R2 ez900 on a H22A AL heatsink with an aspheric lens. I want to run this at about 1.5 amps. I have actually found quiet a few threads online about running this LED but all of the topics I have found went off topic before anyone actually posted a driver for this. What do you guys think will be the best way to run this?

go with a amc7135 based driver. I prefer single mode.

I doubt that a 7135 driver will run in full regulation with the proposed setup. At 1.5A drive, the XR-E will have very high Vf. Eyeballing the datasheet, I would guess around 4V. I doubt 3xD NiMH can deliver enough input voltage to reach full regulation, especially when you factor in the additional voltage drop from various parasitic resistances in the flashlight.

If you want to use NiMH cells and a 7135 driver, I'd probably go with 4xC NiMH and fit them with a PVC sleeve and a tail spring mod.

Justin Case said:

I doubt that a 7135 driver will run in full regulation with the proposed setup. At 1.5A drive, the XR-E will have very high Vf. Eyeballing the datasheet, I would guess around 4V. I doubt 3xD NiMH can deliver enough input voltage to reach full regulation, especially when you factor in the additional voltage drop from various parasitic resistances in the flashlight.

If you want to use NiMH cells and a 7135 driver, I'd probably go with 4xC NiMH and fit them with a PVC sleeve and a tail spring mod.

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+1
4c's would be easier, cheaper, and regulated using the amc7135 based driver.:thumbsup:

Thanks for all the suggestions so far.

Only problem I have with this is that I already have a lot of primary Ds and a lot of NiMh Ds. This would mean buying a whole new set of batteries which in the long run does not make it a cheaper option. At the begining of 2012 I made the effort to get rid of all my different battery types exect 3. I use 18350s in all my normal EDC sized lights, Ds in my bigger Mags and AAAs for my keychain lights. I got rid of all my lights and batteries that would not fall into one of these 3 categories. Which was about half of my lights. so at this point, Cs are not an option.

Can I use a 4D mag?

mikesantor said:

Can I use a 4D mag?

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Sure, will be even better no adapter needed to hold the D cells. The D primarys may not give enough current to be run at 1.5 amps. You would have to try and see. The Nimh will work very well with that current.

awsome. So 4D mag with 7135 driver it is!

Thanks so much guys. This build will be fun!

Ok now the next question. Where can I buy these boards where I DONT have to buy them 10 and 20 at a time?

Illumination Supply.

I have bought several from them with no problems, fast shipping too!

Awesome! thanks Brando.

Justin Case said:

I doubt that a 7135 driver will run in full regulation with the proposed setup. At 1.5A drive, the XR-E will have very high Vf. Eyeballing the datasheet, I would guess around 4V. I doubt 3xD NiMH can deliver enough input voltage to reach full regulation, especially when you factor in the additional voltage drop from various parasitic resistances in the flashlight.

If you want to use NiMH cells and a 7135 driver, I'd probably go with 4xC NiMH and fit them with a PVC sleeve and a tail spring mod.

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You are absolutely correct. All of those hundred of thousands of 3.7V li-ion battery flashlight XR-E users are suffering from dreaded under regulation disorder.

willieschmidt said:

You are absolutely correct. All of those hundred of thousands of 3.7V li-ion battery flashlight XR-E users are suffering from dreaded under regulation disorder.

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That would depend on what drive current the led is driven at. With the amc7135 driver with 4 7135 ic's the output current advertised is usually 1400ma. From my testing they usually are around 1340ma or so. The drive current makes a big difference in the led vf. So getting the right drive current would allow it to stay in full regulation. Or a led with a low vf would also help the driver stay in regulation. Most all the XR-E lights I have bought draw about 1000ma or less. Most with less. Jtr1962 did lots of testing on the XR-E R2. From his testing you could predict the correct drive current to stay in regulation. Given the drive current of 1340ma you would need at least 3.8v from the source to stay in regulation. 4c Nimh's would have a drained voltage of around 4v and should work quite well with good efficiency.

With a xpg r5 at 1340ma the driver should stay in regulation until a 4.2v li-ion battery is drained. The xml would also stay in regulation at that current. These a pretty decent drivers if you can keep the voltage above the forward voltage of the led until the batteries are drained, But not more than 6v input. The closer you get source voltage to the vf of the led the more efficient it is.

Don't forget the fact that real world flashlights have parasitic resistance. Even 0.1 ohms at 1.4A drive translates to 0.14V of drop, which means Vbatt has to deliver that much extra voltage on top of Vload+Vdropout. For the 7135, Vdropout is 0.12V. So, you might need at least Vload + 0.26V. If we go with 007's estimate for Vf of 3.8V, then Vbatt has to be above 4.06V to reach full regulation. If you look at battery guy's AW IMR test data, even the vaunted IMR26500 might hold above 4V under load for about 7 min out of a total run time of over 90 min (assuming 2.2Ah capacity and a draw of 1.4A). Hundreds of thousands of others may disagree, but I don't consider this to be a good choice for a driver. Perhaps those hundreds of thousands like to buy regulated flashlights that don't run in regulation.

Justin Case said:

Don't forget the fact that real world flashlights have parasitic resistance. Even 0.1 ohms at 1.4A drive translates to 0.14V of drop, which means Vbatt has to deliver that much extra voltage on top of Vload+Vdropout. For the 7135, Vdropout is 0.12V. So, you might need at least Vload + 0.26V. If we go with 007's estimate for Vf of 3.8V, then Vbatt has to be above 4.06V to reach full regulation. If you look at battery guy's AW IMR test data, even the vaunted IMR26500 might hold above 4V under load for about 7 min out of a total run time of over 90 min (assuming 2.2Ah capacity and a draw of 1.4A). Hundreds of thousands of others may disagree, but I don't consider this to be a good choice for a driver. Perhaps those hundreds of thousands like to buy regulated flashlights that don't run in regulation.

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If you look at jtr1962 test data 1340ma would be a vf of 3.74v for the xre r2. I just rounded a little. Your are correct with the other voltage losses. To stay in regulation greatly depends on the forward voltage of the led. Like has been said, with a higher xre vf this may not be the best choice of boards unless you are powering from 4 Nimh's. There are better choices for most lights than the xre. This is some test data that leads me to believe its a pretty decent driver. His test was with a xre. With a xpg or xml the drive should stay in regulation alot longer. As the driver drops regulation the light just continues to decrease in brightness. Hardly even noticeable until the batteries are almost drained. I have also used several dozen for various lights. Much better than direct drive and quite efficient. I use the xpg or xml with these drivers And find they work very well. I really dont know of a better driver for a light that uses single cell 4.2v li-ion. It would have to be buck boost depending on the current and led used. The xre at 1.5 amps would probably need a boost circuit to stay in regulation. Are there better drivers for a single cell light that work with a current range of 1.5amps to 3amps.? Someone enlighten me if they are.:thinking:

7135 efficiency is basically Vload/Vbatt, so drewfus's data isn't any big surprise.

I have several lights that use 7135-based drivers, so I'm not hard over against them. And as you indicate, virtually all of my 7135 lights use low Vf XP-Gs and XM-Ls. But IMO folks seem to get the mistaken idea that 7135 drivers are a no-brainer when it comes to using them with 1xLi-ion. They are definitely a low-cost, rugged driver. They fade very gracefully as the Li-ion cell drains. But IMO, one ought to think about Vf, Vbatt, forward current level, Li-ion sag under load, and flashlight system parasitic resistance, as well as the expectations/requirements from a regulated light.

For a buck-boost 1.5A-3A driver, you'd probably have to build a 2xGD750 or 3xGD1000 parallel sandwich. A bit pricey and the 14mm diam and sandwich thickness might be an issue if you need a 17mm, P60-style driver.

Justin Case said:

7135 efficiency is basically Vload/Vbatt, so drewfus's data isn't any big surprise.

I have several lights that use 7135-based drivers, so I'm not hard over against them. And as you indicate, virtually all of my 7135 lights use low Vf XP-Gs and XM-Ls. But IMO folks seem to get the mistaken idea that 7135 drivers are a no-brainer when it comes to using them with 1xLi-ion. They are definitely a low-cost, rugged driver. They fade very gracefully as the Li-ion cell drains. But IMO, one ought to think about Vf, Vbatt, forward current level, Li-ion sag under load, and flashlight system parasitic resistance, as well as the expectations/requirements from a regulated light.

For a buck-boost 1.5A-3A driver, you'd probably have to build a 2xGD750 or 3xGD1000 parallel sandwich. A bit pricey and the 14mm diam and sandwich thickness might be an issue if you need a 17mm, P60-style driver.

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I stand behind my recommendation of the 7135 driver for original listed components, 3D Maglite XPE Tenergy powered aspherical conversion. The availability and cost make it the logical choice for a light throwing toy, not an efficient life or death eotwawki flashlight. The above comments reinforce my opinion.

I've run a lot of tests on 7135 drivers. You can be down a significant amount of drive current if you fall only a few tenths of a volt below the Vin needed for full regulation. The issue with using a high Vf LED like an XR-E with a 7135 driver and 3xNiMH is that starting with fresh cells, you will most likely have Vin greater than Vregulation for only a small fraction of the run time of the cells. Maybe that's good enough. Maybe not. But if you don't know what you don't know, then you won't be able to make any assessment of that issue.

With big D NiMH cells, even a fraction (probably about 1/10) of the full run time of the cells could mean about an hour in full regulation. Maybe that's fine. But if you expect to get 10 hours of full regulation, you will be sorely disappointed. If you look at Silverfox's NiMH shootout curves for the Accupower D NiMH cells, for example, they spend most of their run time at a quasi-steady state Vload of about 1.25V or so. So three cells will give you about 3.8V. Unfortunately, you might need over 4V to reach regulation. That 0.2V shortfall can really cut your drive current. Maybe the difference between 1.4A nominal vs ~1A drive doesn't matter for some folks. It's not my light, so I don't care. My point is that if you simply went with a recommendation to use a 7135 driver with 3xNiMH without any further details, you would have no clue as to these sorts of performance issues I've raised.

Please with the parameters listed state the "Off the shelf" driver you would recommend. Or does this thread end like the second to last sentence in the first post? Enquiring minds want to know.

If you are refering to using 3 Nimh's as justin case mentioned. You would need a buck boost driver to stay in regulation. I dont know of any that will give you a decent amount of current. Using 4 Nimh's The amc7135 driver will work well with a xre. With a single cell li-ion quality 18650 the xpg or xml would be the better choice. A xml at 1.5 amps of current 3.1 vf with the amc driver should stay in regulation around 95% of the battery discharge. A xpg r2 3.36vf at the same current maybe 80%. The efficiency should be good. These numbers are just speculation but should be close. This driver works well with the correct setup.