Help Boosting Output on This 12v LED Driver

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garrybunk
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Help Boosting Output on This 12v LED Driver

 

I'm working on this 6x Cree XB-D (right?) "off-road" light and would like to boost the output a little.  I'm using the light as a floody area light and not looking to use it for "off-road", so I don't need extreme output.  In stock form this light floods an area 30ft x 30ft fairly brightly, so I'd guess around 1,000 lumens.  If it's easy to boost a little I would like to.  I'll likely post a simple build thread when done.

Pics of the driver:

1

2

To see the traces:
2

 

Closeup of components:
w

 

I need to recheck current draw on a good battery, but during my test using a weak 12v SLA battery it was drawing about 0.5A @ +/- 12v.  I doubt it's even drawing 1A max.  Is R4 a current sense resistor?

Thanks,
Garry

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wight
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  • R4 is certainly a current sense resistor. The normal math applies – cut the resistance in half to double the current, etc.
  • Is that an MCPCB?
  • Is it double-sided? Modes? What exactly did it come out of? Just curious.
  • Err, are there loose wires just sticking out of inductor “L1”??
  • Cree’s XB-D has a much smaller footprint than XM-L2. Four XB-D should fit in the same space as one XM-L2. (they are only 2.45×2.45mm vs the XM-L2 at 5×5mm) Is that what you’ve got? (in the pictures they look very large for 2.45×2.45mm)

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

garrybunk
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This board is single sided (mounted directly to solid aluminum) and is from these lights (just grabbed a random Ebay link for them).  I'm guessing they are XB-D, but perhaps they're XT-E?  They are smaller than XM-L's but I didn't measure them.  Yes, I broke that inductor but resoldered that wire back on (and light works well).  No modes, just on/off with a very crisp cool-white output. 

Any idea of how much boost is safe for these LED's?  (Guess that's hard to say not knowing if they are XB-D or XT-E.) 

Thanks!
-Garry

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wight
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XT-E are easy to identify due to the “X” across the die IIRC. These don’t look like XT-E to me.

What is the LED wiring configuration?

The little drive circuit may be the limiting factor.

Thanks for the link.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

garrybunk
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I think they're 3S2P, but I'd have to verify. This one is reassembled, but I have a second one to disassemble yet. 

-Garry

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wight
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For now I’m just going to connect these two modding threads about the same light to make sure nothing gets missed. – Gearshredder – Lightbar mod ‘18w’ 6x XB-D cree

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

Gearshredder
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What a coincidence haha. That sense resistor R4 0.15 ohm, gets you 10w probably. I’ve got the values in my thread wight posted.

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Thanks wight!  I would have missed that thread otherwise.  I have a selection of sense resistors on-hand.  How much draw from a typical 12v car battery would be "safe" and fairly "negligible" in terms of running a battery down if left on for hours?  I'm sure 1A is safe and I'm guessing 2A would be pretty safe too.

-Garry

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garrybunk
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Wait a minute, diode SS210 is only rated to 1.5A (datasheet here).  I believe I have extra SS54's from another project; can I swap the SS210 to the SS54 (an SS54 datasheet - assuming this datasheet is correct)?  Any other components limiting me from boosting to about 2A?  I don't know what that little FET is rated for (no markings on it).  I do have some "AO3400" ("A09T" chip marking - datasheet here) I could swap in. 

Thanks,
-Garry

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Gearshredder
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-A standard lead acid has a capacity of 44-50 AH. You do not want to get below 80% with these. That gives you 8.8AH.
-I’d be worried about the inductor becoming over saturated and heating up. I might be able to check this later.
-when I opened mine up, it was drawing 0.86A at 13.45V. Yours is going to be a bit less.

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I just found a diode that exsisted on another one of my dead drivers. (Datasheet for SS34 )
It’s advertised at 3.0A

wight
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The whole driver looks weak to me. Tiny FET, weak looking inductor, weak diodes. If there’s space I’d be tempted to swap for something different at $2 or so.

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

garrybunk
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That's the problem, there really isn't any space.  There is no "driver cavity".  Solid aluminum behind and the reflector assembly & lens to the front.  Perhaps I'll just aim for 1.5A.

-Garry

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garrybunk
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Ok, measured current from a 12v power source (an old PC power supply I use to power my hobby charger).  Getting about 0.95A with voltage under load measuring 11.75v.

s

a

 

So replacing my R150 with an R100 should get me to 1.5A current draw.

-Garry

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garrybunk
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Well I finally got around to replacing that R150 with an R100. I went ahead and “potted” the components before I put it back together. I also reworked the mount so it’s adjustable without tools and I don’t have the end of the bolt hitting the bottom of the light head. Haven’t taken beamshots yet and can’t tell yet if it even appears brighter, but it should be. I’m measuring a consistent 1.56A now.

-Garry

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wight
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Looks like progress. I suppose that’s a magnetic mount?

Still fine, still on a break. One day I’ll catch up with you folks! previous wight catchup Wink
list of my drivers & variants (A17DD, FET+1 stuff, WIP stuff, etc)

garrybunk
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Yes, “40lb pull”, plenty strong enough to hold the light. Sorry, it’s “25lb pull”. It’s available at Home Depot or on Ebay.

-Garry

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SawMaster
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I like the magnetic mounting!

Based on what numerous dashcam users have said, a 1.5A draw should leave you with enough juice to easily start the average car ~48 hours later but you’re reaching the point where a weak or old battery may fail you. Diesels need more cranking power so maybe ~12-18 hours for them. I think that’s plenty of runtime for your purposes Big Smile

Phil

garrybunk
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I wouldn’t plan on using this (vehicle not running) for more than maybe an hour or two. My intention is for night mountain bike rides when you’re parked in complete darkness and need light to unload your bike from your rack and get all your gear setup on you and your bike. A standard headlamp (i.e. on my head, not the car’s headlight) was ok, but not ideal. I also figured I could flood the parking lot with light for other’s to see as well. I had thought to mount lights to the underside of the trunk lid, but I have to keep the trunk shut while I’m unloading/loading the bike. Also makes a nice roadside emergency light. I have 10 feet of cord on it. One thing missing yet is cloth on the bottom of the magnet so as not to scratch the mounting surface.

-Garry

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garrybunk
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Ok, quick build post added to ““My Bike Lights” thread”:http://budgetlightforum.com/comment/902354#comment-902354.

-Garry

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whitevancam
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Garry
Followed your directions from the mtbr forum to here, thanks for the tip.
I have another question and this is probably a better place than the mtbr forum.
How do these compare with your modified cycle lights??
I only ask as I need something 12v ( my bike electrics seem to sit around 14V when the engine is running ).
Am keen to do something on a budget and am not afraid of a soldering iron and a bit of tinkering.
Are some cheap and cheerful lights like these, 1 x Flood and 1 x Spot, both with a little bit of a boosted output a reasonable option for me ( mounting on a KTM for trail riding) ??
Thanks again for the help.
Steve

garrybunk
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This particular one isn’t that bright. Bright enough for my needs and I have the flood version only. Someone else could probably post up if another one works better.

Honestly, my heavily modded BT40S blows this away. And you could even get more output than my BT40S by using XP-L emitters.

-Garry

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