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Author Topic: 24 Volt power to 12 volt lights  (Read 720 times)
Tikvah
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« on: June 03, 2011, 05:32:28 AM »

Tell me if this is right.  I can run two 12v lights in series using 24v power?

I'm considering changing all my clearance lights to some new LED fixtures.  I don't want to just put a LED "Bulb" in, because the old fixtures and lenses need updating anyway.

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I couldn't repair my brakes, so I made my horn louder.
1989 MCI-102 A3
DD 6V92 Turbo, Alison
Tons of stuff to learn!
Started in Cheboygan, Michigan (near the Mackinaw Bridge).  Now home is anywhere we park
gumpy
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« Reply #1 on: June 03, 2011, 05:43:48 AM »


Well, your diagram is correct and should work ok.

Having said that, I did exactly what you describe, using Maxxum LED lights. Nearly every single one has burned out. I'm in the process of replacing them all
and rewiring them to feed off my 12v toad supply.

I can't say if it was the connection method, or just crappy lights. I'm leaning to crappy lights, because the one's I've replaced them with are already starting to
burn out.  My next step will be to find a differnent brand or build my own.

Just be aware of that possibility.

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Craig Shepard
Located in Minnesquito

http://bus.gumpydog.com - "Some Assembly Required"
scanzel
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« Reply #2 on: June 03, 2011, 06:01:49 AM »

This is just my opinion but I see more leds light on cars trucks and over head street signals burned out than conventional filament lights. In all the years I have have a Honda and Jeep I have only changed out 4 bulbs. On my conversion I a put on all new clearance lights and just put 24v bulbs in them. Bought all the bulbs on www.Bulbs.com. A 75 cent bulb is cheaper than a whole new led unit. The 24v stuff is out there you just need to look little harder. The military still uses it. If going from 24v to 12v use diodes or put in relays instead if you really need to go to 12v.
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Steve Canzellarini
Berlin, CT
1989 Prevost XL
Bill B /bus
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« Reply #3 on: June 04, 2011, 05:56:11 PM »

I have replaced all my marker and running lights (turn,tail and stop) with LED at 12V. Relays were used for the running lights because they are also the TOAD supply. You can use 12V LED's in a 24V circuit with a dropping resistor is series at each light.

Assume actual 27V for voltage. Determine current for LED. Usually will be in the 200-300 milliamp range. Read as 0.2-0.3 amp. E/I=R Where E is 13.5V,  27V divided by 2. I is the current specified by the manufacturer. R will be in the 100-150 ohm range for marker lights.

In my case the cost of replacing most of the fixtures,(leaking,rusty, broken/cracked lenses) was more than replacing with $7  8 LED fixtures and a $.10 resistor.

Bill
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Bill & Lynn
MCI102A3, Series 50 w/HT70
buswarrior
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« Reply #4 on: June 04, 2011, 06:42:03 PM »

A good used take out Vanner battery equalizer and you can create an entire 12 volt sub-system in the coach for all manner of things, while retaining your heavy duty alternator and starter circuits.

Be careful with cheap and home brew electronics, I know a MCI 102EL3 Renaissance in a first line coach company that a fire started in the stock rear clearance lights, heat set the foam insulation on fire.

The transit coach scrappers have battery equalizers coming out their ears. Some transits were equipped with pairs for redundancy.

happy coaching!
buswarrior
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Frozen North, Greater Toronto Area
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