The International Cessna^® 170 Association

Did some tests today with just the battery powering the system. Put a charger on the battery, then turned on the master switch. Ammeter barely moves, very slight discharge. I then turned on the landing lights which showed about 15 amp discharge (just like Bruce said). Turned off the landing lights and turned on the nav lights/rotating beacon (they are on the same switch in my aircraft) which shows 7.5 amps discharge. Then turned off nav lights/beacon and turned on strobes which showed 5.0 amp discharge. Just the radios shows a 2.5 amp discharge and the electric turn and bank shows 1.0 amp discharge, lower than I thought it would be. Turning everything on together shows about 30 amps discharge. So no wonder the 20 amp generator breaker would pop.

If you had asked me, I would have given you those exact numbers. Not that I know your aircraft, it is that these numbers are pretty consistent throughout the fleet. Was worse when you had tube radios. LEDs as they replace the incandescent bulbs will reduce the load significantly.

sreeves wrote:Did some tests today with just the battery powering the system. Put a charger on the battery, then turned on the master switch. Ammeter barely moves, very slight discharge. I then turned on the landing lights which showed about 15 amp discharge (just like Bruce said). Turned off the landing lights and turned on the nav lights/rotating beacon (they are on the same switch in my aircraft) which shows 7.5 amps discharge. Then turned off nav lights/beacon and turned on strobes which showed 5.0 amp discharge. Just the radios shows a 2.5 amp discharge and the electric turn and bank shows 1.0 amp discharge, lower than I thought it would be. Turning everything on together shows about 30 amps discharge. So no wonder the 20 amp generator breaker would pop.

Sorry to be so slow in picking up on this conversation.

YOur generator CB does not interact with your landing light circuit. YOur battery does all the power to your landing lights. All your generator does is RECHARGE your battery. If your gen CB pops, it's because there's a defect in your gen/reg/cb or wiring. (Chances are that your regulator is underrated and is popping that CB. Keep in mind that the CB MUST NOT be rated higher amperage than the wire it serves can safely carry. That CB should not be a 35A CB unless the gen/reg circuit has 8 ga wire, although 10 ga has been used in some cases, it is marginal.)

The 35 A gen needs a 35 A regulator to be capable of a full 35A output. That also requires a wire of sufficient gauge to carry that load. (I don't know where you read in the El.Svc Manual that the gen requires a 4 or 6 ga wire because that is not what is printed for that circuit.)
The 35A gen/reg installation requires an 8 ga wire from the Armature to the Regulator ARM terminal, and also on the REgulator BAT circuit, which also passes thru the cockpit CB which should be rated at 35A slow-blow or 40 fast.
I suggest you re-read the El. SVC Manual again to carefully review that circuit.

And by the way, there are automotive 35A regulators available from autoparts stores that meet the intent of AC23-27 and may be used for less than $50. I've posted those part no's previously and a search should find them, but I'll research again and post.
Hope this helps.
Edit: Here are the reg nos : The AutoZone part numbers are Wells, VR602 20A regulator , the VR605 25A unit , and the 35A VR699 . They are Physically interchangeable with the original units, but are intended for the automotive purpose.

The entire posting about troubleshooting generator system is here: http://cessna170.org/forums/viewtopic.p ... reg#p42449

sreeves wrote:Did some tests today with just the battery powering the system. Put a charger on the battery, then turned on the master switch. Ammeter barely moves, very slight discharge. I then turned on the landing lights which showed about 15 amp discharge (just like Bruce said). Turned off the landing lights and turned on the nav lights/rotating beacon (they are on the same switch in my aircraft) which shows 7.5 amps discharge. Then turned off nav lights/beacon and turned on strobes which showed 5.0 amp discharge. Just the radios shows a 2.5 amp discharge and the electric turn and bank shows 1.0 amp discharge, lower than I thought it would be. Turning everything on together shows about 30 amps discharge. So no wonder the 20 amp generator breaker would pop.

Even with the 30-amp load, the regulator should have limited the generator output to 20 amps, and the remaining would be supplied by the battery and show up as a 10-amp discharge. The most continuous load you should expect the system to keep up with is 80 percent of the generator output, or about 16 amps in your case. To prevent nuisance breaker pops with loads at or above the generator rating (assuming a properly functioning regulator and breaker), you could upgrade the wiring and breaker to 25 or 30 amps. The battery would supply that last 10 amps, but that's better than 30. If you want to pull 30 amps continuous, you need about a 40-amp generator or alternator system.

Let me reiterate: If the gen CB is "popping" there is a FAULT in the GEN/REG system....NOT the landing light system (which should have it's own CB/fuse appropriately rated for that circuit.)

One reason the gen CB may be opening might be the regulator is defective or improperly-rated for the existing generator. Another might be a defective (internally grounded) generator. I suspect it's the regulator.

Landing light circuits are "INTERMITTENT" circuits and do not need to be accounted for when deciding upon charging system output requirements. (Although many like to have sufficient generating power to prevent short-term discharge, it is not a real problem since landing lights are used for approach/landing and takeoff/departure short periods of time. The taxi lights can be used for identification in flight and will reduce by half the power requirements in most aircraft.)
IF you are sitting awaiting takeoff clearance for a long period of idling, then turn the land/taxi lights OFF.... not only to avoid battery run-down but also to avoid irritating others around you that are also awaiting or who are arriving and don't need your lights in their eyes. IMO

I tested the approved LED lights in my B-model and was disappointed in them. They did not place a strong 'beam' where I wanted (I usually operate on a dark-hole ranch-strip without auxiliary airport-lighting or reflective surfaces and need all the light I can get. It's why I installed the dual system I"ve posted about elsewhere. Even so, I find the incandescent lamps superior to LEDs.

gahorn wrote: I tested the approved LED lights in my B-model and was disappointed in them. They did not place a strong 'beam' where I wanted (I usually operate on a dark-hole ranch-strip without auxiliary airport-lighting or reflective surfaces and need all the light I can get. It's why I installed the dual system I"ve posted about elsewhere. Even so, I find the incandescent lamps superior to LEDs.

Pointing out George is talking about LED landing lights, not nav lights. Depending on what you have for a rotating beacon, if you even have one, between an LED in the rotating beacon and 3 nav lights you will cut nearly 6 amps from the load when nav lights are on.

I prefer the color from incandescent bulbs, but the LEDs I have are much brighter. Also, I can run the LEDs full time and unlike 4509s they last more than 5 hours. I'll never go back to red-hot filaments.

Correctomundo!, Bruce..thanks for pointing that out.

DaveF wrote:I prefer the color from incandescent bulbs, but the LEDs I have are much brighter. Also, I can run the LEDs full time and unlike 4509s they last more than 5 hours. I'll never go back to red-hot filaments.

Yes, if you are standing/flying/sitting somewhere and look at LED land/taxi lites....they certainly appear brighter.... but I found they did not illuminate targets as well as incandescents. LED land/taxi lites are a lot like the automotive headlites we see these days on the hiways. Oncoming autos w/LEDs really blind you. This is because they "scatter" their cold/blue photons instead of focusing them onto the pavement down/in-front of the oncoming auto. LED advertisements sometimes show more details of objects outside the normal perimeter of vision....but that is wasted energy if you're wanting to see the focal-center ...and farther-out/distant ...where your lamps are aimed. (LED is better if desiring more illumination in the periphery, closer-in.)

Incandescents are better focused and will better illuminate the "spot" where they are aimed. Now the problem in dark areas is the periphery ...and I take care of that by installing "flood"-type lensed lamps (4461s) rather than the "spot"-types (4509s).

Now, to be fair..., the 4461 lamps are actually motorcycle headlamp intentioned. (Before anyone gets their shorts in a wad, my installation is approved using that lamp.) They are 60 watt and not 100 watt. And I have a DUAL landing/taxi light installation. (set of two on each wing leading edge). I use the dual taxi (4461) on-arrival/when in the pattern and they get everyone's attention. The 4461 lamp has a "Fresnel" or "fog" type lens which spreads the light rather than focusing in on a "spot"....which is perfect for taxying around. They are 300+-hour longevity, and since they draw only 120 watts when both are ON... my airplane experiences an actual reduction in electrical-draw when illuminated (over the two 100-watt (200-watt total) original land/taxi installation.)

I'm not saying my arrangement is for everybody because most folks are unwilling to spend the kind of money req'd on such modifications, and most don't operate in the dark-hole my rural ranch-strip provides. But the entire project allowed me to install incandescent on one side and LED 4509 on the other for comparison ...and the difference was STARK. The incandescent illuminates CENTRAL-OBJECTS better, while LED was more visible to others and drew less power.
(I sold the 4509-LED to another member who never reported back as to how he judged it.)

Here is the entire text from the experiment I ran several years ago:

gahorn wrote:

gahorn wrote:...I have standard 4509 landing lamps and 4461 taxi lamps in my custom dual light installations written about elsewhere.

I have on order an LED which claims to be a "perfect" replacement for the 4509, which I will trial and write about here and perhaps the 170 news. It is U.S. made by Grote and costs about $100 at amazon. I plan to install it in one of my dual landing lamp mounts, and thereby have a fair comparison of the performance versus the original incandescent 4509. I am not doing this because I want/need LED land/taxi lamps. I consider $100 each to be outrageous. I am only doing this out of LOVE for you guys.

It arrives in a few days and I'll try to get a report written by the end of the month.

For the impatient, here is the product, and it sells for $99.99 at Amazon plus $10 shipping.
Grote Trilliant® 36 LED Whitelight Work Lamp 63821-5

I received the product and installed it in my right wing position. (Many of you will recall I have a mirror-image, dual landing/taxi light installation.)
The Grote light is indeed a very good quality lamp. It is strongly built, and an exact fit to replace our PAR 36 4509 landing lamps. It was an easy install, exactly replacing the PAR 36 lamp.

Remember that I have one 4509 and one 4461 PAR 36 lamp in each of my dual installations. The 4509 is a 100 watt landing lamp which has a clear, spot-light beam type lens,... and the 4461 is a 60 watt taxi lamp which uses a "Fresnel" type (more of a "fog" or "scattered" beam lens. When I decided to install dual land/taxi lights I purposely selected the 4461 for my taxi lamps because I wanted more of a "wide" beam illumination when taxying,... while I enjoy the longer-projection "spot" pattern of the 4509 for landing lamp purposes.

For this test, I installed the Grote LED lamp in my right "taxi" position. This removes the right 4461 lamp in my right wing and allows a direct comparison to the 4461 in my left wing. Here's what I found:

The Grote lamp is an EXCELLENT replacement for the 4461 taxi lamp. It makes a MUCH better TAXI lamp than the 4461.
It also makes a MUCH BETTER TAXI lamp than the original 4509 taxi lamp which Cessna installed.

It makes a much BRIGHTER light and also makes a MUCH WIDER illuminated area than my 4461 taxi lamps. However, in comparison to the original 4509 landing lamp, it does not provide the depth/distance of illumination as does the original 4509 landing lamps. This is what I actually expected as that is the reports that I have had from other LED substitutions when compared to incandescent lamps.

The original incandescent PAR 36 lamps are more "yellow" while the Grote LED is more "sunlight" brilliant. I definitely PREFER the Grote LED color for illumination. I also PREFER the Grote LED as a TAXI lamp ...than either the 4461 incandescent... OR EVEN the original 4509 Landing lamps being used for taxi purposes. (With my dual set-up however I do not intend to leave the Grote unit installed. If one has only a single land/taxi installation I believe the Grote LED is a superior lamp for the taxi lamp position.)

If I had only the original set of landing/taxi lamps which Cessna installed in our metal-wings.... here's what I would recommend:

Keep the original 4509 PAR 36 lamp for a LANDING LIGHT.... but remove the 4509 TAXI lamp, and REPLACE IT with the Grote LED product for a TAXI lamp. I think everyone would be extremely pleased with the increased illumination of the Grote LED in the TAXI position because of it's brighter color and greater spread of illumination for taxy purposes, and would also enjoy a HUGE reduction in electrical demand while using the taxi position as an anti-collision light in congested areas (yet still retain the distance-capability of the 4509 landing lamp when entering the pattern and lining-up on final for landing.) The Grote LED is advertised with a 40,000-hour life. This should mean that as an anticolllision/recogniton and TAXI lamp it will likely be the LAST TAXI LIGHT you will ever purchase.
But I do not think it will satisfy you for a landing lamp. For that you will be happier with leaving one of the 4509 lamps in place for that purpose.

To reiterate, .... in my opinion, the Grote LED is the perfect TAXI lamp replacement and I would recommend removing the 4509 taxi lamp and installing the Grote LED in that position.... while keeping the 4509 in the LANDing position. I think that would be the PERFECT SETUP for anyone who has the original land/taxi lights in their 170 A/B or 172, and might give some relief to those who have experienced short life of their 4509 lamps (because the Grote LED would take on the task of anticollision/recognition service) while IMPROVING the TAXI-light illumination of the original setup and simultaneously reduce total electrical demand.
I do not recommend the Grote for a replacement of the LANDing light or to replace both lamps, however.

Now that I've run this test, I have a deal for anyone who might want a Grote LED PAR 36 with only ten minutes of use on it... (I will be keeping my dual-setup intact)... I will ship it to you and I will pay the freight. (You only need pay for the lamp - $99.)
By the way, I checked with one of our Members who runs a trucking repair/service facility and found that this price is about $30 below wholesale... so if you want one, this is your opportunity to get it below wholesale and free freight.)

I like to fly with my taxi light on for added identificaion. I purchased a bulb at a local supply house (forgot which one) but may have been O'Riley's or Auto Zone aircraft supply that is sold for George's Ford tractor. It has the things on the glass George mentions that scatters the light, but they are much cheaper than the ones used for landing lights.
As it happens, I visited with a couple of friends this afternoon who have installed LED bulbs for landing/taxi that came from Larsen Lighting Co. I haven't researched exactly what part #'s they used, but they cost around $26.00 each. Much less expensive than Whelen and others. Don't know the legality but from what they tell me they tell me they work well. One of them put a LED bulb in the tail socket, as I did, but his also has a flashing ring around the constant bulb portion. Pretty neat and attention getting.