Can I fix this LED driver?

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pwd   10 kW

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Can I fix this LED driver?

Post by pwd » Nov 24 2021 10:58am

I have these LED drivers which both failed after less than 5 hours each. My estimate is that they failed because they are rated for an input voltage of 10-80VDC but my pack is 86.1V full. I didn't notice when the first one failed but the second one failed when I turned it on via a simple on-off switch.

Can these boards be repaired and improved to handle the 86V input without popping? :flame:
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IMG_20211124_103401409_HDR.jpg
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IMG_20211124_103401409_HDR.jpg (381.68 KiB) Viewed 143 times
IMG_20211124_103351292_HDR.jpg
led2
IMG_20211124_103351292_HDR.jpg (328.46 KiB) Viewed 143 times
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amberwolf   100 GW

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Re: Can I fix this LED driver?

Post by amberwolf » Nov 24 2021 8:12pm

The two most likley parts to fail are the small IC chip and the FET. You'd need to know what those parts are, and find their specs, to see if they are designed to handle the voltages your system makes (including any spikes that occur at any point in operation/etc.).

If they aren't, then you'd need to find equivalents that *can* handle those voltages.

FETs are usually easy enough to find, but that IC might be harder. You might have to use the original, and add a DC-DC converter (that does handle the voltages well, at the currents the LED driver board needs) between the system and the board.


The diodes could also be underrated but that's much less likely.
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E-HP   100 MW

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Re: Can I fix this LED driver?

Post by E-HP » Nov 24 2021 8:32pm

It may be easier to get a buck converter, and either use those LEDs or get some with 12V drivers and run them off the converter. The XML Cree LEDs use about 10W-15W, so you should be able to drive 2 or 3 off of one $5-$6 buck converter.

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pwd   10 kW

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Re: Can I fix this LED driver?

Post by pwd » Nov 25 2021 9:59am

Thanks for your input guys. I going to choose a suitable DC - DC converter and try feeding the boards 12V. I have ordered some replacement boards/drivers for this light instead of attempting to repair the existing ones.
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Magic Pie 4 front w/ Infineon 4 Clone @ 70A phase + Leafmotor 1500 rear w/ Infineon 4 Clone @ 200A phase
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Offroad Build viewtopic.php?f=6&t=102195:
2019 Rocky Mountain Blizzard 20
Cyclone "3kw" 13T motor to 36T chain ring then 32T chain ring to 11T-46T Cassette @ 100A phase
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mintycrayon   10 µW

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Re: Can I fix this LED driver?

Post by mintycrayon » Nov 25 2021 12:50pm

Look at how the solder pooled around R4 and R5. This suggests to me that the board over-heated by a lot. Maybe R4 and R5 turned into surface mount heating elements and gave up. Other than the solder pooling did they crack too?

If you insert a buck converter to lower the DC input to the LED built-in buck converter it will dissipate heat between the two boards. Buck converters sometimes have a heat-sink recommendation, or a built in heatsink, so you may want to give this extra attention.
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E-HP   100 MW

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Re: Can I fix this LED driver?

Post by E-HP » Nov 25 2021 1:07pm

mintycrayon wrote:
Nov 25 2021 12:50pm
Look at how the solder pooled around R4 and R5. This suggests to me that the board over-heated by a lot. Maybe R4 and R5 turned into surface mount heating elements and gave up. Other than the solder pooling did they crack too?

If you insert a buck converter to lower the DC input to the LED built-in buck converter it will dissipate heat between the two boards. Buck converters sometimes have a heat-sink recommendation, or a built in heatsink, so you may want to give this extra attention.
Sharp eye, and easy to see on the second board now that you pointed that out. And based on the traces, it looks like those two resistors carry all of the current.

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