O-290-D Alternator Conversion

[8337]

It moves to discharge side. I have original panel with piano keys. Fuses are below it and screw in. How would I figure out what fuse is for what?

I’m was thinking of getting a volt meter with alligator clips and hooking it up to generator and firing her up

[6643]

How would I figure out what fuse is for what?

They are supposed to be labeled. Also, the operation manual should cover it, too.

Do you have a wiring diagram for the charging system? There is a straight forward procedure for testing a generator system, but you need to know which of two configurations you have. Generator and regulator part numbers can also tell you what you are dealing with.

[8359]

Just an update.

The solar charger appears to be working great. Even on a cloudy day it's keeping my battery in the mid-13V range. This weekend I flew to Santa Barbara and Camarillo, 3 hours of flight time and I had no issues. The only major difference was keeping the transponder off until run up complete and the charger.

I think for now I'm happy keeping the generator in there, I'll have to revisit when I try some higher loads at night with the lights on (need to swap out to LEDs) and maybe a phone plugged into the cigarette lighter.

[6643]

Are you getting a positive reading on the amp meter? If not, something is still amiss. It could be the meter is incorrectly wired, or the generator isn't charging.

Does the discharge rate decrease when you go from idle to cruise? If so, it does indicate the generator is doing something. If not, it's not...

It shouldn't be necessary to keep the battery on a constant charge when the plane isn't flying for short time periods.

[8359]

The amp meter does go slightly positive, but it's hard to read how much, I think the scale on my meter is too large (+/-60amps).

So to clarify, when I'm at cruise, amp meter should be positive. At idle it should decrease but still remain positive depending on load (possible to dip into negative)? The amp meter is measuring amps into our out of the battery? Or generator?

Yea, I know I shouldn't need to for short time periods, but I'd rather just keep it plugged in for now. I'm not on enough of a flying schedule where I know if my next flight will be in a day or 2 weeks.

Thanks for the help.

[6643]

So to clarify, when I'm at cruise, amp meter should be positive.

Correct. As long as the load doesn't exceed the capacity of the generator. Any situation where it does should be temporary. Landing light, flap motor, hydraulic pump, gear motor, etc are intermittent loads and can cause the load to exceed generator capacity. Total continuous loads are not supposed to exceed 80% of generator capacity.

At idle it should decrease but still remain positive depending on load (possible to dip into negative)?

No, at idle the generator voltage output is less than the battery voltage and the regulator will not connect the generator to the system (reverse current cutout). As you increase the engine speed the generator voltage exceeds battery voltage slightly and the generator "comes on line". At this point the amp meter should start to move to the right, but not necessarily into the positive range. If your lights and radios (that are on) draw, for example, 15 amps, then the meter will not show a positive charge until the generator output exceeds 15 amps. The generator should come on line around 1200-1500 RPMs. As the generator speed increases the current output also increases and eventually the generator should be carrying the entire electrical load, including replenishing the charge on the battery.

The amp meter is measuring amps into our out of the battery? Or generator?

The battery. If the reading is negative the battery is carrying some or all of the load. The battery is discharging. If it is negative but less than the total load then the generator is carrying part of the load and the battery is discharging, but at a lower rate. If it is zero then the generator is carrying the load but not charging the battery, and if it is positive the generator is carrying the entire load and charging the battery.

When the master is off and the engine is not running the meter should read zero (in the center.) If it does not, note where it is. This is the zero point for your meter. Anything to the right indicates charging and to the left discharging. Note that I've seen more than one meter that was not wired correctly and did not correctly indicate a charge. With all the accessories switched off and a moderately discharged battery you should be able to see a significant charge on the meter. Plus 10 amps or more would be normal in that situation.

Have you looked at the data plate on the generator to see what its capacity is? How about the part number off the regulator?

[8359]

Thanks for the detailed response John, very helpful.

I did look at the generator data plate, it's buried somewhere in this thread. It is a Delco-Remy 12v/20Amp generator. I have not looked at the regulator yet, will take a peek next time I pull off the cowl.

[8359]

I shot a couple touch and goes last night and had some issues again. I think the system just can't handle all the lights, radio and transponder, at least in a touch and go environment when I spend half the time at idle.

I got about 0.4 on the tach before things started to quit. I think I'm just going to go ahead with the alternator conversion for piece of mind.

I spoke to plane power and they didn't have a good recommendation on a kit for the O290D. I called B&C and they recommend the BC400 since it was approved for many airplanes (not the 120/140) and also the O290D. Next step is to get the FSDO on the phone and try to get an appointment to get verbal approval before I buy any parts.

[6643]

Next step is to get the FSDO on the phone and try to get an appointment to get verbal approval before I buy any parts.

May I suggest a safer approach?

Get with your IA. Fill out all the paper work including schematics, parts list, continued airworthiness procedures and the 337. Take (have your IA take...) all that to the FSDO and apply for a field approval. Don't spend any money on parts until you have a signature in Block 3.

Get with B&C and use their approval for a similar alternator in the 120/140 and their approval for the alternator on an O-290 as acceptable data.

[4004]

If you have made the decision for the alternator ( right one) then you should review ALL the comments you have received. Contact the STC holder and discuss issue - contact Lycoming since the engine is obsolete and no TCDS - do they have archive copy of TCDS - that listed an alternator? FAA? Have you reviewed the Lycoming Service Instruction 1154 - your dealing with obsolete engine but what's the history. Check the O-290D parts manual - on page 5-3 they list the parts to mount an Alternator - why this listing if they didn't have an approved alternator?

In General Aviation News publication there is a column by a retired Lycoming employee that answers questions - you may send him your issue - he probably still has contacts in Lycoming with access to the historical info. If you find an approved alternator to the engine, then there shouldn't be any problem getting the FSDO to field approved to your airframe STC conversion, if required by them. Preface on Block 8 of 337 - "In interest of safety.....night flight...….."

IIRC your engine morphed up - O-233,O-235,O-290,O-290D,O-320 with new current TCDS - they kept the O-235 for the 150s which had alternators and also the 0-320 - an 0-290D (if not already alternator approved) could possibly use the 0-320 mounting setup. 2c

Big Edd