How to wire a ND alternator
QUOTE=stick-n-rudder: I have a nippondenso single wire alternator on an RV-3. Can someone give me a good wiring diagram for a single wire install and answer some questions?
Questions:
1. I am told you need to use a lead acid battery and that the diodes in this alternator won't allow a charge on a composite (dry cell) battery...is this true and if so, explain why thoroughly?
Single wire? I doubt it. If there is only one wire to hook up it is not a ND alternator. Also a true one wire alternator is not suitable for aircraft.
DRY CEL? Well no one uses DRY cels in aircraft, at least for the main ships battery.
Good news is the typical set-point (voltage) is 14.5 volts on ND alternators. This is the perfect voltage for both lead acid and what we use, the Odyssey battery (per Odyssey technical info, voltage should not be less than 14.2 or more than 15.0 volts). You may be confused with Gel Cel, which is old hat 1980's and not state-O-art. The Odyssey is a SLA (sealed lead acid) or AGM (absorbed glass mat). The two terms are interchangeable and basically same thing. They are also recumbent batteries (sealed electrolyte).
2. How do you shut the alternator off?....with a breaker switch? IF so, how do you connect a large wire to those switch terminals?
Good question. First it would be helpful to say what model you have? That would be good to know.
Niagara has a good dwg showing the warning light (ND w/ out remote volt sense)
http://www.niagaraairparts.com/alt-instr.pdf
More specific ND info (wiring) troubleshooting as installed in a Toyota
http://www.autoshop101.com/forms/h8.pdf
(not all ND alternators have remote V sense)
You will need two/three circuit breakers and or fuses / fusible links (CB):
-B-LEAD: CB 5-10 amps greater than Alt's rated output (pull-able type CB required)
-IGN LEAD: CB 5 amp (pull-able type recommended)
-Warning light: use a small fuse/ CB.
-Voltage sense: Fusible link would be good if connected to battery, or
-Optional V sense wiring to buss use fuse/cb or fusible link. (You can make or buy a fusible link.)
It's critical you turn the alternator ON before starting the engine and leave it on until you shut the engine down (alternator not turning). There are 3 or 4 wires on ND alternators, depending on the model. They all wire in a similar fashion except some have a remote voltage sense:
B-lead: output should be routed direct to a Circuit Breaker on the panel and than to your main electrical buss or positive side the battery. Usually the battery and alternator leads meet at the main buss, since they both are a source of power (critical never run the alternator with out the battery connected). Some claim that if you use a CB on the panel you will get electrical noise. This is plan flat not true.
The IGN wire: (This is not a FIELD WIRE) IT DOES NOT TURN THE ALTERNATOR ON AND OFF. What turns the alternator ON and OFF normally is starting and shutting the engine down (spinning the alternator pulley). You wire the IGN wire to the main buss thru a CB or fuse. A pull-able CB is best. What the IGN wire does is tell the regulator to wake-up or go to sleep. IT IS NOT MEANT or DESIGNED TO TURN THE ALTERNATOR ON OR OFF WHILE IT IS RUNNING (even though it may do this you can't count on it if the regulator fails). In the event the alternator needs to be isolated from the aircraft (electrically), you pull the B-lead CB in the PANEL, PERIOD end of story. I recommend a DPST switch for the ALT/BAT (double poll single throw). That way with the DPST switch you are always sure the alternator and BATT are turned on/off together. YOU MUST NOT TURN THE IGN WIRE OFF OR THE BATTERY MASTER OFF WHILE THE OTHER IS ON. With the Cessna split switch you can turn the alternator on / off accidentally while the alternator is energized and under load.
The only time you want to remove power from the IGN wire while flying is if the alternator has a problem, BUT your first and primary action is to pull the B-lead CB first. Remember you DON'T normally turn the alternator on / off unless typically one of the following occurs:
The voltage is too high
The voltage is too low (dead)
The voltage is irregular or unstable
(Note: Highly recommend a good high/Lo voltage indicator on panel)
Now if the alternator is dead and no longer needed, you already pulled the BIG CB on the panel for the B-lead, isolating the alternator, you now can pull the CB for the ALT or IGN wire, avoiding possible unnecessary drain to the regulator if you like. This is how it works in cars, which these alternators designed for. You don't shut the alternator down in a car do you? No.
L or LIGHT (WARNING): This should be hooked up. Van omits this and leaves it disconnected. This is a mistake in my opinion. It is not only a "no charging" light, it's a fault light for the voltage regulator (VR). The VR is a microprocessor and can send a fault signal out and turn the light on. Use it. Any 12 V bulb will work. If you use a LED you need a DROP DOWN resistor, or use a LED that already has the resistor and made for 12 volts.
Remote Voltage sense: This is meant to wire direct to the POS terminal of the battery. However Van again simplifies the wiring and just ties it together with the IGN wire at the alternator plug. You can not leave the remote sense dis-connected or the alternator will not work properly. It is a good idea to use it as designed. If you do the Van recommend piggy backing onto the IGN wire it will work, but the voltage output may be 0.10 volt higher at the battery. I also think (not 100%) the voltage regulator looks at the B-lead voltage and the remote sense to provide better short detection and protection. Remember the VR is a microprocessor and it looks at the alternator and the wiring connected to it for shorts. I would use it if you have it. Cost and weight of a wire and a fuse/link is nil.
3. Anything else I should watch out for?
Depends on who you talk to you. The topic is full of rhetoric and some urban legends of massive proportion. Two things that seem to be showing a trend lately is:
1) turning the alternator on and off under load (spinning)
can WILL cause damage (mentioned above),
2) Van's rebuilder / supplyer may have QC problems; consider other sources for rebuilt alternators.
Take a look at this Thread about over-voltage protection. It was started to discuss the need for adding OV onto the ND alternator which is internally protected from OV. It got pretty lively but I made a few post of my opinion of what you should do in wiring and operating ND alternators.
http://www.vansairforce.com/community/showthread.php?t=4089&page=1&pp=10
George
