Dimming LED light strings

FuzzyGrub · Apr 26, 2022

Adding red LED light strings to my DMI 1648 Mod-V for night time bass fishing. The main strings will be under the rail or just under the front deck. I plan on two short strings near the bow, so you don't step too far. These will be on the lip of the rail, so will be brighter to our eyes. I'd like to dim those down. Is it as simple as adding a resister in series? If so, what wattage and values should I be looking for?

Also adding green and red strips to the front for nav lights instead of mounting a base and pole.

We use an electric steer trolling motor and couldn't see which way it was pointed, at night. Adding some short nav leds to the top of the head with a push-button on/off switch. They will also be too bright. I testing them in series, and it was too dim.

Thanks for any assistance.

DaleH · Apr 26, 2022

You need to contact these people ... and see what they advise: https://www.superbrightleds.com/cat/single-color-dimmer-switches/filter/Volts_Typical,12,100,3898:

Just be cautious, as dimming typically produces 'heat' as a by-product of lessening the delivered voltage, and that's not good if your wiring/installation can't safely handle it. Meaning, I'd buy/use a specific LED dimmer made for 12V circuits and wouldn't try to try a cheap DIY option ...

MN Fisher · Apr 26, 2022

Exactly what Dale said

Having done hobby electronics, and buying my LEDs from Super Bright for years - trying to 'MacGyver' a solution without having that background will probably end up with blown LEDs

Get a dedicated dimming circuit - it might cost a little bit, but at least your LEDs will be safe.

onthewater102 · Apr 26, 2022

LED's need to be designed to be dimable in the first place, they work differently than an incandescent bulb so it's not as simple as adding a rheostat.

FuzzyGrub · Apr 26, 2022

Thx for the quick replys. The LED strips I bought for the bow arrived this morning. I might not need the dimmer after all.

There is a black, light blocking rubber on the sides. This might be enough not to shine directly into the eyes of someone standing on the deck. I will have to mock it up to test though.

FuzzyGrub · Apr 26, 2022

Spreaking of "MacGyver", I was working on the trolling motor directional LED indicator. The short LED strips I got for that were not flexible, so only one is getting mounted on the centerline which has the least amount of curvature. I used both foam pads to take up the gap.

Right after I drilled the 1/2" hole for the push-button, realized the 12V would only be there when the prop was turning.

Then, realized that it wasn't a "true" 12V but a pulsed speed control. Before going any further, went and tested it. When the prop just starts to move, the LEDs do glow. Dim, but easy to see at night. As the speed is increased, they get brighter. So, lucked out there.

Waiting on glue and liquid tape to dry before finishing the wiring and installing.