Install a switch after step down for lights?

How-Tos & Esk8 mechanics How-Tos
#1

Can i install a 12v switch after the step down (75v to 12v) for my lights? Will the step down drain my batteries, since i cant turn it off?

#2

Not sure, but if you have room for a step down consider 3 18650s to power your light. It’s what I ended up doing instead of the step down.

But there is then the extra port needed to charge it :face_with_diagonal_mouth:

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#3

I strongly suggest running the lights from the board battery and not separate cells.

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#4

This will drain your battery. You should use the same switch that turns your ESCs on and off. Check out this diagram for the BMS:

If you use an ESC that also controls the power and you don’t want a separate switch then it starts to get messy — but you can do it with an extra couple pieces, a FET and a resistor.

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#5

Thanks for the info. I do have an ESC that controls power (100D), so i guess ill need to add a switch before the step down.

Any recommendations of a switch that isnt a loopkey that can handle an 18s voltage?

#6

Digi-Key 528PB-ND

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image640×640 40.9 KB

I use these. You can get a rubber cap to make them waterproof.

#8

First we need to know the reason you don’t want to use a loopkey. Appearance? Cost? Multiple pieces? Need fingerprint security? Trust issues? Waterproofing? Svelteness?

Tell us what you are having an issue with.

#9

What buck/stepdown you using? Most of them have an EN pin that simply isn’t used. Can use that for on/off :slight_smile:

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#10

KNACRO DC Converter DC 24V 36V 48V 60V 20-75V to DC 12V 5A 60W Car Power Converter Waterproof Shockproof Dustproof Suitable for Car Audio, Monitoring Equipment, Display, Electric Fan, Motor, etc https://a.co/d/b9RzuA1

I havent bought it yet, have a recommendation?

#11

Hmm why?

#12

I had experience in the past with my loopkey falling out, im hoping for something better looking, and dislike the multiple pieces. If thats the only recommendation- thanks for the input.

I also want to see what options are out there. (If any)

Thanks guys

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#13

You can also just use a simple disconnect switch from any major hardware store. The ones there are all rated well above what you’d need, but still have no issues interrupting a 12 volt supply. I have one of the rocker switches as the power switch for the LEDs I use on a shelf and haven’t had any issues with it.

Only downside is that the options available do tend to be larger, but they’re cheap and you don’t need to wait for shipping. Just make sure that it has usable leads on it and that it isn’t designed to slot into some housing.

#14

Do you store your board standing on end, or on hooks, or just sitting on the floor?

#15

Haven’t figured it out with the new board im building, since its much bigger(flux).

I own a tayto that i diy’d that is propped on a guitar stand.

https://a.co/d/dgk9JVF ChromaCast Folding A-Frame Stand for Acoustic and Electric Guitars with Secure Lock (CC-MINIGS)

#16

Aww, if you stored it standing on end maybe some switch where the lights turned on whenever it wasn’t propped up on end :crazy_face:

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#17

I like the outside of the box thinking!

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#18

I’d be cautious of this. Idk about all of them, but my cheapo chineseium step-down seems to bleed through a 50 kOhm resistor when turned off this way. That is only like 10-15 mA of draw, but I definitely don’t want that.

Also, there seem to be people suggesting low voltage switches I wouldn’t trust as I would put a switch before the stepdown for sure. Since it’s only 60 W from what you linked you probably only need a switch capable of ~1 A and ~75 V. These are the only thing I come up with on mouser that aren’t fairly expensive:
switch 1
switch 2

They’re rated for 80 V 5 A.

This is the search I did if you want to see the other options: Mouser Search

A loop key is definitely the easiest way for anything with much higher power draw, but for a couple amps IMO a switch like that should be fine. Others may disagree though.

Edit: Also besides these or a loop key you could use a switch to activate a FET or relay. Since switches exist that seems the simpler and likely cheaper option to me.

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#19

Also, you could try switches rated for different currents and things. I tend to just buy things that say they’ll do what I want them to do, but if I were going to do anything out of spec I’d probably buy some switches rated for 125 V and at least a few amps AC and I think there shouldn’t be a big problem there. TBH, I’m not sure exactly how and why the AC and DC ratings on switches vary. DC can sustain arcs sometimes when AC won’t because it doesn’t effectively switch on and off, but I’m not sure how exactly that figures in to switches and their contacts.

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#20

Very helpful. Thank you

#21

Description says that they’re good for 5a 14v. I’m no engineer here, so is there something I’m not understanding that would make it suitable as a switch before the buck?