Alternator Warning Light Question

[koupster]

I'm using 12V LED Panel Indicator Lights like this: https://www.digikey.com/product-deta...12V-ND/3150546

Cheers, David
RV-6A KBTF

[rapid_ascent]

I used those same LED Indicators on non-aviation projects. They come in different colors, even bi-color if I recall and seem to work fine.

[lr172]

Originally Posted by koupster

I'm using 12V LED Panel Indicator Lights like this: https://www.digikey.com/product-deta...12V-ND/3150546

Cheers, David
RV-6A KBTF

Yes, good example of an LED indicator with a built in resistor. I used them on my 6.

[fixnflyguy]

I have a small red LED for my indicator(Radio Shack RIP), and it too glows dimly when all is fine. Its almost un-detectable in daylight flying, but when I did have an actual failure in flight (broken crimp terminal) the light became very bright and I noticed it immediately. I have got used to it, and its a reminder to me that the light itself is testing good...I'm leaving it well alone!

[Raymo]

If you have an EFIS with engine monitor, you can tie it in directly as a contact and avoid another hole in your panel.

[bjdecker]

Originally Posted by nobubbles63

I am looking, belatedly, at fitting an alternator failure warning light from the L post on the standard alternator. I have read on other posts that an LED light will need a resistor fitted into the circuit to stop the LED glowing dimly all of the time.
Can anyone advise what size of resistor is needed to fulfil this task.
Thanks
Derek

The Plane Power Alternator indicator light is a 100mA, 12V incandescent bulb. If you are going to replace it with a straight LED, you should put in a 120ohm (R=V/I, thus R = 12/.1) resistor between the LED and the +12V rail.

When the field is removed, the Lamp circuit closes and current will flow from +12 to gnd via the LED+Resistor.

If you can navigate mouser or digikey and find an LED+Resistor combination, all the better; just remember the correct Resistance / current

On the G3X, you can wire the L circuit directly to one of the GPI's and configure it for active Low; I believe, and G3Xpert can confirm, GPI's are good for 30mA.

Cheers!

B

[FinnFlyer]

Originally Posted by bjdecker

The Plane Power Alternator indicator light is a 100mA, 12V incandescent bulb. If you are going to replace it with a straight LED, you should put in a 120ohm (R=V/I, thus R = 12/.1) resistor between the LED and the +12V rail.
...
B

Please realize that a LED typically uses way less current than an incandescent bulb. Thus your match is off. Just because the PPA can supply 100mA is no reason you have to use it all (unless you want an LED or LEDs to light up the cabin and blind you in the process).

Use the 470 ohm resistor mentioned earlier and expect it to emit a small amount of light even when things are fine.

Possibly a 9 volt zener diode instead of the resistor may prevent the dim light.

Finn

[nobubbles63]

Many thanks for all of the replies, I will have a go at this when lockdown ends and see what I can work out.
Derek

[Veetail88]

Looking for knowledge, I came upon this slightly dusty thread and thought I'd add to it. Just for a data point, I've been running a 60 Amp Plane Power alternator for almost 6 years with an LED indicator lamp from Stein wired to the alt failure lug on the alternator and it's been working fine for the entire time. I suppose the Stein Air alternator may have a resistor built into it, but I sure didn't add one.

My actual problem however is that it's been working perfectly all too frequently. The thing has been tripping the Alt Field breaker since the beginning. Yes, I have a 7.5 amp breaker in place. Started with a 5, and changed it when the problem became obvious. Same result. Also, yes, I've changed the plug connector as well.

The problem has been intermittent. Some flights the breaker won't trip at all, sometimes for many flights. Other times, it'll pop once or twice per hour or more or less. I haven't been able to find any scenario where it happens more than others.

The weekend before last, In 10 minutes time, it would pop the breaker almost instantly each time I pushed it in. Assuming the main alt trash, I went for a flight last weekend using the backup SD8 and thought I'd try the main alternator. Pushed in the breaker and it stayed online for the full 40 minute flight.

Anyway, I'm about done with the Plane Power unit and want to switch to an off the shelf unit from O'Reilley or somewhere, but that means I'll have to add an external regulator and OV protection.

All that said, my actual question is, how do I wire the alt failure light with the new setup. It seems the PP alternator has a lug for that but standard car alternators don't. Pretty sure this has been done, so I'm looking for the easy answer from someone who has gone before.

[airtractor8]

Anyway, I'm about done with the Plane Power unit and want to switch to an off the shelf unit from O'Reilley or somewhere, but that means I'll have to add an external regulator and OV protection.

All that said, my actual question is, how do I wire the alt failure light with the new setup. It seems the PP alternator has a lug for that but standard car alternators don't. Pretty sure this has been done, so I'm looking for the easy answer from someone who has gone before.

This subject has been covered before many times . If you do a search there is a whole wealth of info available.

Having said that, these guys have an overvoltage module for use with internal or external regulators. Their page also has the wiring diagrams for both types for you. The external reg. diagram is showing the generic Ford type regulator hook up. https://www.periheliondesign.com/lovm.htm If you decide to go with a B&C external reg like this one, it has over voltage protection included. https://bandc.com/product/alternator...14v-homebuilt/