Battery not charging on 78 Tique

Battery not charging on Tique, pulled alternator off and had bench tested at parts store; it passed with flying colors I was told. On a new battery I could barley start boat after 5 starts in 7 hours on water not running any electronics. On volt meter while running, testing battery terminals it reads around 12.2 which is also same charge on battery not running. I tested back of alternator and was getting close to 40 volts at 1000 rpm connected to battery lead and ground to block. Is there some kind of external regulator? Why would I be getting that high of reading off of alternator and nothing at battery? Thanks for help

Yes, same motor that’s in pic. Would a bad voltage regulator have any adverse effects on anything else? Everything seems to function as it should, at least I think it does. I know in the past I’ve had a difficult time with parts for this motor, any suggestions for the voltage regulator? Thanks for the advice

Swingmatt wrote: . I know in the past I’ve had a difficult time with parts for this motor, any suggestions for the voltage regulator? Thanks for the advice

Matt,
Get the model of your alternator and do a search for a voltage regulator for the model. It's ether that or convert to an internally regulated alternator.

Swingmatt wrote: Battery not charging on Tique, pulled alternator off and had bench tested at parts store; it passed with flying colors I was told.

Matt,
For piece of mind, call them up and see if they will test the alternator along with your voltage regulator. Did they even ask you about the regulator or even mention it? They should have since it's an integral part of the charging system.

Depending on the alternator your regulator may even look like this

my regulator looks like the one in previous reply picture, not this one

Beginning to sound more like a poor connection somewhere. Start at the battery and work backwards. Both positive and negative terms. If a connector is not making a good solid contact then the alternator sees the wrong picture and won't charge correctly. It will still operate the starter because of high amp draw, but then will not charge with a lower amp draw. That would also account for the ultra high voltage. And if that is the case no amount of new alternators will fix it. Just a thought.

matt,
Here's a older wiring diagram that does show an external voltage regulator. It may help in your wiring quest!

8122pbrainard wrote: matt, Here's a older wiring diagram that does show an external voltage regulator. It may help in your wiring quest!

Matt

I'll throw this out there for ya.

This diagram is for an early PCM with a Prestolite alternator and a Prestolite external regulator.

You haven't exactly answered the question of what kind of alternator and regulator you have so be careful using the diagram. It may or may not help.

If your alternator and regulator cross referenced to a 78 F-350 with a 460 in it, you don't have much chance at all of having them be from Prestolite

And.........if it came in a vehicle it probably isn't a marine alternator either. Maybe they found something similar but not exact.

Do you have an ammeter or a voltmeter in the dash ?

If it's an ammeter, does it work?

If it's a voltmeter, does it look like the rest of the gauges or maybe something that was added over the years?

With an ammeter, all of the alternator output goes through the ammeter on it's way to the battery. It's a long and winding road from the alternator output connection up to the ammeter, thru the ammeter to the ignition switch, then back to the battery side of the starter solenoid, then to the battery.

You can see most of this on the PCM diagram earlier in the thread (which could be drawn a little better) but for wiring setup with an ammeter, all of the alternator output goes through it no matter what brand we're talking about In other words a dead (open circuit) ammeter will prevent the alternator from charging the battery

The flicker might mean it's working but I'd temporarily jumper around the ammeter with some 10 gauge wire and see if you're getting a charge to the battery.

Also, with the new regulator installed what is your voltage on the Battery terminal on the alternator when the engine is running?

Swingmatt wrote: Voltage from battery terminal on back of alternator at 600 rpm is 26-30 volts, and at 1200 rpm is around 60 volts. What exactly would I jumping to and from to get around ampmeter?

Well with 60 volts coming out of it, I wouldn't do anything that could supply the electrical system. Edit keep reading through the thread and you'll see that 60 volts is what will happen when the alternator is not supplying the electrical system (oerating with no load on it)

If you do you'll cook every 12v electrical piece of equipment on the boat.

You really need to figure out your voltage regulation issue before doing anything

You mentioned the regulator being a Motorcraft, what's the alternator?

Since you can't put pictures here, what do you have for wiring connections on the alternator?

So just to make sure you understand 60 volts will kill everything electrical on the boat so don't bypass the ammeter or really do anything till you get the voltage straightened out and it around 14 to 15 volts coming from the alternator

They did not ask about regulator. I agree, stopped my marine shop today, they had no advise other than a referral to a shop that may be able to help. Gonna follow up on that in next day or two.

Matt

There aren't many things that me and Pete agree about but this is turning into one of them.

Your description of what wires go where and the colors associated with them really make no sense. It's not your fault, you got the boat this way

Without help from an auto electric shop or having a Commander wiring diagram in front of you it's just guesswork and with electricity that usually doesn't turn out good.

You did mention a while back thinking about a 1 wire alternator.

Something like a 1 wire Delco marine alternator would probably bolt in pretty easily and it's hard to screw up the wiring with just one cable attached to the alternator.

Pete would probably agree with me about that too.

You would eliminate the external regulator, the old alternator and be cutting or taping off a few wires.

Unless you're running lots of stereo stuff etc. the one wire would do just fine in your boat and it would be pretty easy to help with the wiring hookup.

They're pretty cheap from places like DB electrical (around 60 dollars)

Matt,
Your problem is taking my memory wayyyyy back to my high school shop classes. We had a combined project between auto shop and electronics shop. We were making switch/outlet boxes that we wired into externally regulated car alternators. The switching basically bypassed the regulator feeding I believe the alternator field. Then by regulating engine RPM, the alternator would produce 120 volts for power tools.


You ether have bad wiring between the regulator and alternator or the regulator is bad or the wrong one. Double check the wiring or get both the alternator and regulator to one of those shops I posted.