roy@alanine.phri.nyu.edu (Roy Smith) (07/24/90)
A boat I'm looking at comes with a 5-HP Mariner outboard that has an
electrical output jack that is supposed to supply about 5A for recharging a
12V battery. The current owner says he tried to use it once but ended up
blowing out some of his electronics because the voltage output goes all over
the place. He tried changing the regulator in the motor, but that didn't
help. Anybody have any experience with these sorts of things? Any
suggestions on putting together some sort of external regulator that would be
hefty enough to handle the current load and voltage fluctuations, withstand
the marine environment (i.e. salt air, spray, etc), and have a small enough
voltage drop that I still got something useful out (about 14V for charging
purposes, I would guess)? I doubt a 78xx would do the job.
--
Roy Smith, Public Health Research Institute
455 First Avenue, New York, NY 10016
roy@alanine.phri.nyu.edu -OR- {att,cmcl2,rutgers,hombre}!phri!roy
"Arcane? Did you say arcane? It wouldn't be Unix if it wasn't arcane!"billr@SSD.HARRIS.COM ( Bill Rominger/Cust Sup.) (07/24/90)
In article <1990Jul24.153632.27480@phri.nyu.edu> roy@alanine.phri.nyu.edu (Roy Smith) writes: A boat I'm looking at comes with a 5-HP Mariner outboard that has an electrical output jack that is supposed to supply about 5A for recharging a >12V battery. The current owner says he tried to use it once but ended up >blowing out some of his electronics because the voltage output goes all over >the place. If the mariner motor is a Yamaha manufactured, (it probably is) the Yamaha cat. lists "voltage regulator" Used to stabilize voltage output of lighting coil. Stops blown bulbs bla bla. For manual models only. Also lists: Lighting coil; Adds both lighting and charging capabilities to 4 and 5 hp models. Accessory rectifier required for battery charging. Educated guess: the output is unrectified sine wave from your output coils. Voltage will vary with rpm. Get a 10a bridge rectifier and feed the two motor output leads into the ac input. Take the plus and minus outputs and connect to a standard auto battery, or a garden tractor 12 volt battery. Measure the voltage at the battery terminals and check for an increase with the motor revving. This configuration uses the 12 volt battery as a regulater. It is the same circut as used on a Johnson 1973 115hp outboard. It works. You can get the bridge from Radio Shack. good luck, and let me know how it works. =========================================================================== Warning: This product is intended for use as an intellectual exercise. Any deliberate concentration and ingestion of its contents may cause blindness or insanity. Bill Rominger, Wilton Manors, Florida, USA, The Earth "Eat snook, live longer, release snook, fish longer" DoD#136 ===========================================================================
laforce@krypton.arc.nasa.gov (Soren LaForce) (07/25/90)
In article <1990Jul24.153632.27480@phri.nyu.edu>, roy@alanine.phri.nyu.edu (Roy Smith) writes... > > A boat I'm looking at comes with a 5-HP Mariner outboard that has an >electrical output jack that is supposed to supply about 5A for recharging a >12V battery. The current owner says he tried to use it once but ended up >blowing out some of his electronics because the voltage output goes all over >the place. He tried changing the regulator in the motor, but that didn't >help. Anybody have any experience with these sorts of things? Any >suggestions on putting together some sort of external regulator that would be >hefty enough to handle the current load and voltage fluctuations, withstand >the marine environment (i.e. salt air, spray, etc), and have a small enough >voltage drop that I still got something useful out (about 14V for charging >purposes, I would guess)? I doubt a 78xx would do the job. >-- >Roy Smith, Public Health Research Institute One of the best voltage regulators I know of is.... A lead-acid battery!! Well... think of it as a **VERY** large capacitor. Do you know if the previous owner tried to use the motor as a battery charger, or if he tried to power the electronics w/o the battery in the loop? Were I in your position, I would assume stupidity (on part of prevoius owner), or at least a bad battery connection, and try the following: 1) Determine that the output is DC. Oscilloscope is the best method. 2) Connect battery to output. Check waveform. If voltage observed in 1) is above (about) 14 volts, the battery should charge and the waveform across the battery should be pretty darn flat. We are talking about several farads of effective capacitance. If in 2) there is no significant difference between the battery alone and the battery charging, I would suspect a wiring error on the part of the previous owner. Or, just insuficent understanding of the physics. I would **NOT** try to power anything semi-sensitive from a battery charger w/o a battery in circuit to act as a filter (and maybe not even then ;-). If the voltage is much higher than the battery voltage, i.e. above about 14 volts, you probably should put a resistor in serries with the battery when charging. This should provide correct voltage across the battery. R1 -------------/\/\/\--------------- + | |+ | G B Stuff - | |- | ---------------------------------- The charge current will then be a function of R1 and Vg-Vb. Be sure to work out the power requirements for R1. Anyway, this is what I would try first. It has lots of my favorite features, i.e. cheap and simple. --Soren "laforce@krypton.arc.nasa.gov" p.s. No, I don't have any idea how you will get a 'scope down to the dock. -S.