1962 Johnson electramatic 75hp charging question.

Hi everyone. I apologize if this question has already been answered somewhere on this forum, but I have searched and not found it. I have this '62 75hp v4al-14l that I'm concerned about. Got the motor with a '77 Chrysler sport fury I bought, and it barely ran when I got it. Tuned it all up, rebuilt the carb, etc, and now it runs like a champ. The last thing that bothers me is the fact that I'm not getting a voltage reading at the battery that would lead me to believe its charging. With a fully charged brand new battery, reading 12.9-13.1 volts engine off, the voltage drops to 12.6-12.7 when i start the engine and out it in gear, and idling around at low speeds i watch the voltage slowly and steadily drop over a few hours of being out. If i maintain a higher rpm, the voltage seems to hold, but it never really rises or comes close to being in the range of 13.5 or better, which I would consider charging (based on my experience in the automotive and old motorcycle world). However, I have never run it at wot or cruising range for more than 20-25 minutes at a time, since that's about as long as it takes for me to get anywhere want to go with the boat. I have made sure the diodes are good and ohm checked the stator, as per testing procedures from my seloc manual, all test good. The only thing I am not able to test, since my boat does not have an ammeter, is the voltage regulator. And unless i missed it somewhere, the seloc manual is unclear as to what the charging system voltage is supposed to be. So I guess my question is: Measured at the battery, to indicate that the system is in fact charging, what voltage readings should I be getting at idle out of gear, at idle or low speed in gear, and at wide open throttle? I know the lower unit will fail open if the voltage gets too low, and I would rather not get stranded somewhere... kinda wondering if I need to drop $200 on the new regulator or not. And I would really like to add a vhf and not worry about killing the boat in doing so. Help? I'm not an idiot, just an outboard newbie idiot. Thanks for any input.

Re: 1962 Johnson electramatic 75hp charging question.

The stator output on that model is 20 amperes and normally pins a ammeter if the battery is low. I'd suggest you install a ammeter to complete the electrical circuit before you start throwing parts at it.

Do you have battery voltage to that stator? (required on that type)
Do you have resistance between the two yellow wires of the stator? (required)

There should be no reading between either yellow wire and ground. (ohm meter on high ohms)

Re: 1962 Johnson electramatic 75hp charging question.

Thanks for the reply Joe. I have that schematic in my Seloc manual, which does go over the resistance testing procedures for the stator. I have not, however, checked for battery voltage to the stator. Seems like a pretty simple thing, and the manual didn't mention it... I live near Cleveland, so the boat's put up for the winter, but I'll have to check that first thing in the spring when I pull the boat back out. Also should mention that I checked both fuses in the box, and both are good. For sake of argument though, say that I were getting voltage to the stator and I install an ammeter and the regulator checks ok. I would still like to know what the charging system voltage should read at the battery at idle, low speed, and wot. Anyone have those numbers?

Re: 1962 Johnson electramatic 75hp charging question.

vitallus said:

I would still like to know what the charging system voltage should read at the battery at idle, low speed, and wot. Anyone have those numbers?

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Keep in mind that the voltage applied to the RED field wire of the stator is being applied directly from the voltage regulator. The other wire of the stator field connector (red/black I believe) leads to ground.

The voltage at idle escapes me (don't have that book either) but having owned engines back then when they were new with that 20 ampere alternator setup, it seems to me that with a low battery, that setup registered the full scale of 20 amps. Someone still running one of those engines hopefully will verify or correct this guess.

Just checked my remaining stock... I still have one of those solid state voltage regulators, used but okay. I checked the price book and found it to be listed unavailable since 1984, was $100 even back then.

Re: 1962 Johnson electramatic 75hp charging question.

Yes, the red field wire does come from the regulator BAT terminal, but before it gets that far, it comes from the ignition switch IGN terminal. The other field wire is blue, and goes to the regulator FLD terminal, which is at ground potential when not running. The vibrating regulator interrupts that ground signal when running, to control the alternator output.

I don't have the exact regulator specs handy, but the regulated output to the battery is about 14 or 14.5 volts, so expect around that when running, even at idle.

Have you checked the 60 Amp fuse? That is the first place I'd go. Then check for battery voltage at the field. Grounding the regulator's FLD wire with a jumper wire should cause full output of the alternator (careful--you can blow bulbs that way--and the 60A fuse. Do at slow idle only).

Re: 1962 Johnson electramatic 75hp charging question.

F_R.... Of course you're correct about the voltage source leading to the field portion of the stator. Sorry about that. He did say that he checked both fuses in the box but they're worth double checking.

Re: 1962 Johnson electramatic 75hp charging question.

I mentioned the 60A fuse because most people don't even recognize that it is a fuse. There are two other fuses, 20A, one at the ign switch, and the other in the box. The one in the box is only for the accessory terminals, and if the one at the switch is blown it won't even crank or start. The 60A is the alternator fuse. Reckon we got that straightened out.

Re: 1962 Johnson electramatic 75hp charging question.

Ok... so essentially, the fact that my stator ohms out within spec and my diodes all test good and the 60a fuse is good (I check it every time I pull the cover off the box just to make sure... its still fine...) and I'm still getting a drop in voltage when I start the engine instead of a rise would indicate that I do, in fact, have some sort of charging issue to chase. At least that is clear. Gonna try to find a 30-0-30 ammeter to put in my dash just for the heck of it, and I'll check for voltage at the stator (with it running, yes?), but I'm gathering that I may be looking for a break in the circuit somewhere. As in, the stator may not even be getting the battery voltage necessary to charge and the boat is simply running off the battery. Whether that means a broken wire or bad corrosion at the ignition switch or the regulator itself is simply bad, based on your responses, even though its an electramatic, a drop in voltage with the engine running means I have a problem. Again, thanks for your advice gentlemen. This is the oldest engine I've ever owned and this type of charging system is a bit foreign to me. More complex and spread out than my old bikes. So just to be clear, I'm looking for voltage at the red wire of the stator with the engine running, correct? What voltage reading should I be looking for? It appears that I will have to get my lower unit back together and back in this motor asap and find a can big enough to start it in...

Re: 1962 Johnson electramatic 75hp charging question.

The voltage on the "red" wire leading to the stator field would be 12 volts. This 12v would be present as soon as the key is turned to the RUN position regardless of whether the engine is running or not.

Re: 1962 Johnson electramatic 75hp charging question.

What is the complete model number on your motor?

There were various versions of the 75 HP charging systems. Some hade a small square fuse mounted that was hard to find if not known about.

Re: 1962 Johnson electramatic 75hp charging question.

The motor is a 1962 Johnson V4AL-14L 75hp electramatic super seahorse. The fuse you're referring to is the 60a alternator fuse we've been talking about. Its good. I kinda wish that were the problem so I could be done thinking about it, but alas...

Re: 1962 Johnson electramatic 75hp charging question.

In your original post, you state " I have made sure the diodes are good".

No intention of insulting your intelligence here.... I assume that you did disconnect the diodes before you tested them?

I did at one time many years ago come across one engine (your model and not too old at the time) that had a badly frayed wire at the front portion of the hood pan, due to the steering action no doubt of the engine moving back and forth. Had the effect of now it works, now it doesn't and was a real pain to locate.

Re: 1962 Johnson electramatic 75hp charging question.

Vitallus, perhaps an explaination of how the system works will help. There are two windings on the stator. One is the field stator and the other produces the AC output to the diodes, which changes it to DC. The field winding is an electromagnet. When you turn the key on, 12V is sent to it and then back to the regulator, which grounds that side. So, now you have a current flowing through the field coil, which makes a megnet of it.

Inside the flywheel, you will see a zig-zag pattern of a ring. That causes an alternating magnetic lines of force, which generates an AC voltage in the charging coil. As I said, the diodes change that to DC to charge the battery.

Now, as for the regulator, it grounds one side of the field coil, which completes the field circuit and makes it magnetic. If you were to un-ground the regulator/field circuit, the field circuit would no longer flow and would no longer be magnetic, and no AC voltage would be generated in the charging coil. So what the regulator is going is monitor the battery voltage at the red wire (ignition switch), and when it exceeds a pre-set value, ungrounds the field, and the AC stops being produced. That happens many times a second. Teh regulator is turning the field on and off as necessary to control the AC output.

Did I make that clear?

So, the key to diagnosing this thing is to check the field voltages. With the key on, thre should be 12VDC at the red wire, and the blue wire should be grounded at the regulator. That's why I suggested a temporary ground of the regulator field terminal to see if the regulator is doing what it should-----grounding the field. If your temporary ground makes it charge, and the regulator does not make it charge, the regulator is bad.

If the field circuit is working as required, and there is no charging, there is a problem with the AC output not getting to the battery. Could be bad diodes, blown 60A fuse, broken wire, or whatever.

Actually, this is a very simple system, not unlike many cars of the day. Only difference is they had a belt driven alternator with the field coil, charging coils, and diodes inside.

Re: 1962 Johnson electramatic 75hp charging question.

vitallus said:

The motor is a 1962 Johnson V4AL-14L 75hp electramatic super seahorse.

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I had the same model motor 25 years ago when it was only 25 years old. It served me well for many years but I wanted to share some info with you based on that experience. Prior to that let me give my disclaimer which is I do not claim to be an expert and when forum gurus like F_R and Joe Reeves post in a thread, I pay attention so I can learn. That said, I had to replace the voltage regulator and diodes in the junction box after I acquired the motor. I kept the regulator part number in my files in case I might ever need it again. My dealer provided me with a Delco#90000561 that fit perfectly and lasted the entire time I owned that motor. If you have to buy one, eBay just might be a source.

I also chased an electrical system fault that just about drove me nuts! Eventually, I traced it to the inline 20amp fuse holder in the junction box. Fuse was good according to a continuity check BUT it would not allow the proper current flow. Finally realized the wires of the fuse holder had corroded under the insulation creating lots of resistance. Replaced the fuse holder, wire leads and never had another problem.

I am not suggesting any of the above is your problem but wanted to share my experience with you. Good luck with that great old motor!

Re: 1962 Johnson electramatic 75hp charging question.

Thanks for the tip willyclay, and the heads up about the wiring at the motor hood Joe. Something I will undoubtedly look into. Yes, the diodes were disconnected when I checked them. I actually ended up replacing a couple of them when I first got the boat, but the last time I had everything apart, I disconnected them all again and they checked ok. Will look over my wiring and check for +12v koeo at the red stator wire.

Re: 1962 Johnson electramatic 75hp charging question.

I got to wondering about this thing last night. You said there is no ammeter. Well are the fat green and brown ammeter wires connected to anything, or just hanging loose? If not connected, the alternator is not connected to the battery, so of course it can't charge.

Re: 1962 Johnson electramatic 75hp charging question.

Ok update. Took advantage of the last nice Cleveland day for a while and found...: I AM getting power to the red stator wire, but a whole volt less than what I measure at the battery back to back. Key on engine off I get 12.4 v at the battery and 11.4 at the stator pigtail... also, at the dash, the fat green wire is connected to the batt terminal of the ignition switch, but the fat brown wire is hanging loose... what do these two things tell us?

Re: 1962 Johnson electramatic 75hp charging question.

The "Green" wire of the instrument wiring harness is normally connected to the "Bat" terminal of the ammeter.

The "Brown" wire of the instrument wiring harness is normally connected to the "Gen" terminal of the ammeter.

A fused "Brown" wire which is also connected to the "Gen" terminal of the ammeter leads to and is connected to the "Bat" terminal of the ignition switch.

The other end of that "Brown" instrument harness wire, if you take a moment and look at your wiring diagram, you'll see it is attached to that 60 ampere charging fuse.

Bottom line... the "Brown" wire is attached to nothing so the "Green" wire can not complete the circuit thru the ammeter to the 60 ampere fuse. Install a ammeter and a fused (20 amp) link between the "Gen" side of the ammeter and the ignition switch "B" terminal.

Re: 1962 Johnson electramatic 75hp charging question.

Yep, what Joe said. Your alternator is not connected to the battery, so no wonder it doesn't charge. Hook it up correctly, and it'll probably be fine.

Re: 1962 Johnson electramatic 75hp charging question.

Well, that makes perfect sense... My wiring diagram doesnt have colors or gauges labeled, so I had no idea until I blew up the one Joe posted. Cool... didn't even occur to me to look at the back of the dash... So I ordered an ammeter that I will install when the weather breaks next. The next logical question that comes to mind then is, since the boat wasnt built with an ammeter, how in the heck did anyone ever run this boat without a functional charging system? Was it a common thing to simply charge the battery every time you wanted to use the boat, even though it had an alternator capable of doing that for you? Or was there a way that it hooked up without the ammeter? Or am I simply a victim of some ignorant shmoe doing a hack job swapping motors? I suppose it doesn't matter. Humans... ha. Thanks guys. I'll update when I test out the boat with the ammeter installed.