Does this look safe?

Eastwood · Jul 16, 2021

Does this DC to DC step down looks safe? I’m trying to run a 12v headlight and plan to connect this step down directly to the battery.

The input capacitor shows 100 V and the output capacitor says 35v. It’s rated output is 12v 3a maximum.

That little heat sink though lol

TDB · Jul 16, 2021

I wouldn't.

Plenty of LED ebike headlights out there that will run on 60V or more.

Eastwood · Jul 16, 2021

TDB said:
I wouldn't.

Plenty of LED ebike headlights out there that will run on 60V or more.

Do you think it’s unsafe in general or?

I’ve already installed this headlight and made nice mount for it and have been running it with some 18650 cells. works great but would like to connect it to my battery pack so I don’t have to worry about charging a separate pack.

Eastwood · Jul 16, 2021

TDB said:
I wouldn't.

Plenty of LED ebike headlights out there that will run on 60V or more.

Also this is a Cree LED headlamp. The paperwork shows 10-80volts But the first one I connected straight to the battery and I believe it fried the diode or something. I didn’t smell anything but the light won’t turn on. This second light have been running at 12v. So would like to try the step down but I’ve never used one before.

LewTwo · Jul 16, 2021

I think that I might add an inline fuse

Eastwood · Jul 16, 2021

LewTwo said:
I think that I might add an inline fuse

Yeah I was thinking the same

E-HP · Jul 16, 2021

Eastwood said:
Do you think it’s unsafe in general or?

I have a couple of those for lights. They work fine. Didn't bother to fuse them or anything.

TDB · Jul 16, 2021

Eastwood said:
TDB said:

I wouldn't.

Plenty of LED ebike headlights out there that will run on 60V or more.

Click to expand...

Also this is a Cree LED headlamp. The paperwork shows 10-80volts But the first one I connected straight to the battery and I believe it fried the diode or something. I didn’t smell anything but the light won’t turn on. This second light have been running at 12v. So would like to try the step down but I’ve never used one before.

Which light?

I don't really like or trust cheap buck (that is about what they are worth) convertors and only run them one per low power accessory.

My reservation with yours is we don't know what is under the heat sink. They need to come from a trusted source... outside China.

bike4life · Jul 16, 2021

why not go with a higher wattage boost converter. a 1500w boost converter on ebay is 25 bucks

E-HP · Jul 16, 2021

TDB said:
I don't really like or trust cheap buck (that is about what they are worth) convertors and only run them one per low power accessory.

You can trust them as much as you can trust the cheap Chinese LED driver board that the XM-L Cree needs to work, so just buy a few bucks worth of bucks if there's a concern. :wink:

dogman dan · Jul 17, 2021

Just mount it so it stays dry, but in a little box so the heat sink can breathe. Or maybe just tuck it under the seat.

ZeroEm · Jul 17, 2021

Currently stepping down 72v to 12v for lights with this.

Automotive grade, water restraint and potted. Would still point the wires down.

Had a different type, the vibration took it out not water.

https://www.amazon.com/Converter-Vo...ystem+LED&qid=1626533843&s=electronics&sr=1-1

Eastwood · Jul 17, 2021

E-HP said:
Eastwood said:

Do you think it’s unsafe in general or?

Click to expand...

I have a couple of those for lights. They work fine. Didn't bother to fuse them or anything.

Good to know.

Eastwood · Jul 17, 2021

TDB said:
Which light?

Motorcycle LED Dirt Bike headlamp
https://www.amazon.com/dp/B07S512DKW/ref=cm_sw_r_cp_api_glt_fabc_DWBM31BGTYW6KCP24WGK?_encoding=UTF8&psc=1

That’s the Cree chip

https://cree-led.com/media/documents/ds-XHP702.pdf

Eastwood · Jul 17, 2021

dogman dan said:
Just mount it so it stays dry, but in a little box so the heat sink can breathe. Or maybe just tuck it under the seat.

I should be able to find a place for it in my battery cover. Well it’s an ABS plastic case I made but it has a little bit of room for storage.

Eastwood · Jul 17, 2021

ZeroEm said:
Currently stepping down 72v to 12v for lights with this.

Automotive grade, water restraint and potted. Would still point the wires down.

Had a different type, the vibration took it out not water.

https://www.amazon.com/Converter-Vo...ystem+LED&qid=1626533843&s=electronics&sr=1-1

Well that one looks a lot more professional than my cheap eBay one lol but that one outputs 10amps which is too much for this light

Eastwood · Jul 17, 2021

Here’s a picture of the light installed on the bike. Not bad for under 30 bucks
I made aluminum bracket that screws into the bottom of the steer tube. I put a star nut in the bottom side of the steer tube for an anchor.

Eastwood · Jul 17, 2021

Well I just tested the step down and it works great. The output voltage is 11.7, perfect!
I will go for a night ride and test it out to make sure it doesn’t get too hot, the step down.

Thanks for the input guys!

MadRhino · Jul 17, 2021

If SAFE means it won’t set fire to your bike, this is about where you plan to place it. It can be installed perfectly safe.

If SAFE means reliable, forget that kind. You need to put more money for a good, reliable DC/DC converter.

Eastwood · Jul 19, 2021

MadRhino said:
If SAFE means it won’t set fire to your bike, this is about where you plan to place it. It can be installed perfectly safe.

If SAFE means reliable, forget that kind. You need to put more money for a good, reliable DC/DC converter.

The only other step downs I could find were way too big.
I’m hoping this one is reliable as it’s working great. Tested it the other night on a 45 minute ride. The heat sink didn’t even get warm so that’s a good sign

Well now I have 12V Time for a horn! Beep beep

ZeroEm · Jul 19, 2021

My led lights only pull a few watts. Unless you are running other types of lights it should not get hot.

MadRhino · Jul 19, 2021

Good. You got 45 minutes of reliability, yet. If you can get 45 days, then you can begin to hope.

Check Vicor for quality DC/DC converters.

Eastwood · Jul 19, 2021

ZeroEm said:
My led lights only pull a few watts. Unless you are running other types of lights it should not get hot.

Right, same here this one pulls around 25watts.

Since these DC to DC step downs or so cheaply made, I was suggesting since it’s not heating up it’s a good sign it might last.

E-HP · Jul 19, 2021

Eastwood said:
I put a star nut in the bottom side of the steer tube for an anchor.

Ah, this is what I need. I was thinking about some kind of rubber expanding piece, like bar ends, to place in the bottom of the steerer tube, to bolt a mount too, but the star nut is a perfect solution! :bigthumb:

TDB · Jul 20, 2021

Expander plug is another option.

Does this look safe?

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