Definitive answer? Sure lets try
tobinbasford said:
George,
Could you please tell me where it is written that one shouldn't turn the alternator on/off with the engine running on an IR Denso? Called Van's today, they do the same with all their aircraft.
Thanks
I made it up in my head. ha ha
I've been honest about this from day one. I've nothing in written in blood from Nippon Denso. However I've studied it. If you don't want to read this long analysis story, with no prejudice or harshness, keep doing what you want.
However I feel strongly you can damage your regulator. There's a pattern/correlation of damaged ND's and the operational technique of "turning it on" after start, while the engine is running (and battery is under load). Can this damage a perfectly good regulator? I think so.
Great question. I can't prove religion, origins of the universe and meaning of life, but here is goes.
First Van says OK? Really? Who did you talk to? They have a lot of chiefs over there. I talked to Tom Green two years ago about the QC problem they had with the rebuilt ND units they sold. I pointed out they could get top quality NEW clone units (new, not rebuilt) for less than what they said they where paying for rebuilds. You typically get a blase', mildly disinterested affect from Van & company when suggestions are made. They admitted they sell alternators in the catalog for convenience, demand, not that they want to. Not saying they don't care, but its not their core business. Basically ho-hum from them. I'll say it, Van's aircraft is not the source of alternator expertise.
Van A/C switched alternator vendors last year. May be I had something to do with it? I like Tom and first met "Van the man" in the late 80's, they are not folks that change things on a whim. I explained to Tom why turning the alternator on after start may hurt it. I got some response, but they are so "laid back", its hard to tell. I explained they should include complete wiring instructions, including the LAMP. They have not done that. Oh well.
Now to answer your question with questions, why or how you hurt the alternator by turning it on after start?
>> What is a #14684 nippon denso made for, application? A car
>> How does the alternator work in that car application (specifically the IGN lead)? It comes on with IGN and stays on the whole time, even during start.
>> What functions does the regulator have built into it? It has a "soft start" function. With the IGN lead powered the alternator will not come on line or power the field until it "sees" RPM and time delay, logically detected by the micro-chip. It will than ramp voltage up slowly so there's no overshoot, beauty!
This is a fact from the specs.
I called Nippon Denso. Unfortunately corporate headquarters in america is marketing & distribution only, not engineering. If I spoke Japanese I'd talk to Denso engineering in Japan.
I can tell you 100% for sure, it's designed to come on-line and off-line automatically. No manual intervention is needed. My theory, manual intervention CAN hurt it. Evidence shows that (below). Here's the inside of the IC chip. Really take 30 seconds and read the block diagram. (thumbnail - click twice for full size):
You see IGN delay circuit, Thermal limit detector, current limit detector, over voltage detection, digital controls....... This is a motorola chip, ND is similar, but you get the idea. It has 100's of transistor in one IC chip. There is more to the regulator, like the power transistor that controls the field, but this is the BRAIN.
>> How many transistors in external regulators (ie IR's and ER's are different)? About 2 or 3 transistors, one/two diodes, handful of resistors and a capacitor or two. There's NO digital & logic controls or protections w/ ER's. Plan & simple and that's the charm; does not care if when you turn it on. Here's the inside of a typical ER:
>> When you start your PC computer do you boot start 5 programs before it boots? When you shut it down do you pull the plug out the wall or do you "shut it down"? Same with the alternator
Old ER alternators did indeed get CUT out with the cars ignition switch when turned to start. They drew 5-7 amps from the get go. Turning them off gave more juice for start.
There's NO doubt how a IR is designed and should be installed and operated in my opinion. MANUAL intervention = not needed and likely harmful.
>> WHY are we doing extra work? Why throw switches, making more work for your self ? I've not flown a Cessna or Piper in a long time, but have 1000's of hours as a pilot & instructor in them. I recall you turn on ALT/BAT together and start per the AFM. I never played switch monkey with GA planes. Why start now on the RV, especially with a ND that does not need you to do that?
>> Is there an advantage to what you are doing? NO, your ND draws about 50 mA during start and will stay that way until so many seconds after the alternator is spun. Also the IGN lead never draws more than 50 mA. All the power for the field comes from the B-lead and only after a time delay post start. ER alternators may have some advantage waiting, a little more power to start but not with the ND, its done by the IR's logic control .
>> My anecdotal evidence? The alternators that pilots had problems with, almost every one I talked to involved PIF - Pilot Induced Failure, meaning it was a common thread, they all did what you did, turned the alternator on after start. Keep doing it. Prove me wrong.
CASE IN POINT: Document case - Pilot flying decided to turn ALT off for grins to "see what would HAPPEN". He saw amp meter drop. Satisfied he turned it back on. The alternator went instantly OV. He was able to turn the alternator off again with the ALT switch (power to IGN). Which is nice but not what the IGN wire is for.
IGN logic controls wake, sleep and fault reset modes of the regulator. The solid state switching inside is probably not robust enough to take on an alternator that is spinning FULL SPEED. The alternator logic may see a charge need and spike, damaging the IC chip. It expects to start from park, not turning full blast under load. Note: This is all conjecture on my part.
>> Niagara Air parts sold ND alternator kits, brand new OEM Nippondesno units, not rebuilds or clones. I have one. The instructions specifically say use a DPDT master switch so you
don't turn the alternator on an off while the engine is running. A pull-able CB in the IGN circuit can be used if necessary to remove power with the MASTER on.
Do they know something?
>>
Can I prove you're hurting the alternator by turning it on after start? No, but I think so. Correlation with failures and what I affectionately call SMS - "switch monkey syndrome" is high.
KISS principle - why throw switches and add work load where none is needed. Turn both BAT/ALT on and forget it, than off together after shut down, simple. Start your engine, pay attention to RPM, oil pressure, ATIS and the ramp area for safety, your ND is AUTOMATIC. The B737 made me throw a gang of switches after start to bring generators on line. The B757 takes care of it automatically. Let the MAGIC work.
Do as you like, but if your alternator starts to act wacky, you may have contributed to it. I suggest you don't do what you're doing. THERE IS NO ADVANTAGE, AND THAT IS A FACT.
How can I put it more plainly, IR's have a microprocessor, an IC chip that takes care or the START and STOP. Over-riding it can damage it. Install and operate them like they where designed for (toyota/suzuki/sprint).
