Discharge but no charge

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Model T Ford Forum: Forum 2015: Discharge but no charge
Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Saturday, October 17, 2015 - 05:50 pm:

Okay, to start with, this problem has to do with my Model A, not any of my 4 Model T's, but then it seems to me like the charging system is pretty much the same on either "T" or "A", so here's my problem,.....and question......?

Replaced the Model A old & tired 6 volt battery with a 6 volt Optima. The charging system worked perfectly until I started this little battery replacement project, which should have been no big deal (even for me). But then there's my history of not getting along very well with anything electrical!

Cleaned up any corrosion with baking soda water and little brass brush and tried to do everything carefully and properly. Fired up the engine and the ammeter shows no charge at all, in fact, stays right on zero except turning on headlights shows about 12 amp discharge for dim head lights, and about 18 amps discharge for bright headlights.

I had put the new Optima on the charger for a little while before I installed it and I know that it was fully charged, so my thinking at first was that maybe the ammeter stays at zero just because the battery is fully charged and doesn't yet need charging, but then with the headlights on and ammeter showing discharge, the engine/generator does not seem to have any effect on the 12 amp dim light load, or the 18 amp bright headlight load,...the ammeter just shows steady discharge.

From a bunch of receipts that came with the car when I bought it last year, the cutout is of the "diode" type, whatever that means. Remembering my experience with my first Model A when I was a kid (about 60 years ago) I tapped on the cutout pretty vigorously with the plastic handle of a large screwdriver, as I remembered that the old original style cutout when I was a kid would sometimes "stick", but I'm not sure that tapping on a "diode" type cutout makes any sense. And to repeat, an hour before with the old battery, the ammeter showed about 8-10 amp intitial charge, settling back to about 4 amps after running for a few minutes,....all normal, right?

An obvious "upgrade" that I have planned since I got this Model A is one of John Regan's Fun Projects, Inc. voltage regulators, but that would be a mistake right now I think, because I'd like to restore the present charging system to working order before anything else. No use adding a new voltage regulator to my charging system until I know for sure that all the rest of the charging system is in good order. And there's sure as heck "something" wrong!

So, all that to say, what the heck could have gone wrong with a perfectly working charging system, just from installing a new battery? "HELP"! Please,........thanks,.........harold


Top of pagePrevious messageNext messageBottom of page Link to this message  By Frank van Ekeren (Australia) on Saturday, October 17, 2015 - 05:53 pm:

Maybe you fitted the battery in the wrong way? if I remember rightly A's are + earth.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Georgetown TX on Saturday, October 17, 2015 - 06:19 pm:

Ditto what Frank said - the diode cutout only works if the battery is installed with polarity that matches that of the cutout.

Which brings me to my point:

Model A folks love to modify their cars. One popular modification is reversing the polarity of the car. The Model A vendors sell 6 Volt diode cutouts that are negative ground.

So you need to know for sure what type cutout is installed. Either way the first thing I would try is reversing battery polarity.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Saturday, October 17, 2015 - 08:10 pm:

Thanks Frank & Royce - I'm a little more worried now that I think about what you both said. As a matter of fact, I did install the battery backwards just momentarily. Being used to the much more common negative ground systems, I first attached the cable from the starter to the positive post on the new Optima battery. As soon as I just placed the ground cable on the negative battery post, I heard a slight noise that sounded like it was coming from under the hood. Quick inspection revealed that the generator was "motoring" very slowly. (I keep the fan/gen belt as loose as possible without slipping). I quickly went back and pulled the loose gound cable off of the negative post, removed the starter cable that I had already tightened to the wrong battery post, and then remembering that Model A's are a positive ground system, I turned the battery around and installed the cables properly,.....starter cable to negative post and ground cable to positive post. So, now I have three questions,.....

1.) Did I do any damage to the diode type cutout or generator?

2.) Could this be the reason my ammeter does not show any charge?

3.) If so, what do I do to fix it?

Thanks again guys for any additional help,.....sorry to ask such stupid questions, but that's how ignorant I am of anything electrical,........harold


Top of pagePrevious messageNext messageBottom of page Link to this message  By Mark Gregush Portland Oregon on Saturday, October 17, 2015 - 08:43 pm:

Chances are the generator is ok but the diode might be fried. If you have an old working mechanical cut out you could try that for a stop gap. The mechanical cutouts do not care which post the ground is. You could of course do a quick check on the output at the post with the cutout removed.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Royce in Georgetown TX on Saturday, October 17, 2015 - 10:15 pm:

Whatever you do, do not start the car. You can short the generator to ground and the car will be safe to drive, but of course the generator will not charge. Send the faulty regulator to John Regan at Fun Projects to see if it is any good. Likely it is a throw away now.


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Sunday, October 18, 2015 - 08:28 pm:

Success! Thank you Royce, Mark & Frank. Apparently, the generator and diode type cutout are okay. With additional help from this wonderful forum, I "flashed" the generator, then (thinking that if the damage is done, it couldn't get any worse) I started the engine and to my delight, the generator now charges as it always has, prior to my stupid mistake of momentarily connecting the battery cables backwards before being reminded of the fact that Model A's have a positive ground system. Whew! Got away with THAT dumb stunt! Thanks again all,......harold


Top of pagePrevious messageNext messageBottom of page Link to this message  By Bob Gruber- Spanaway, Wash. on Sunday, October 18, 2015 - 09:24 pm:

Hey Harold,
I use electricity to start fires!
Works good.


Top of pagePrevious messageNext messageBottom of page Link to this message  By HARRY A DAW Troy, Mo. on Sunday, October 18, 2015 - 10:45 pm:

Could someone refresh my memory on how to flash the system please?


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Sunday, October 18, 2015 - 11:32 pm:

Harry - I successfully did it, but not sure I could explain it properly with the correct electrical terms,.....but all I did was to take a length of wire and hold one end of the wire on the "hot" stud on the starter motor where the battery cable attaches, and touch the other end of the wire to the terminal on the cutout where the generator field wire attaches. From what I read on the forum here, this momentary contact only has to take place for a second or two, and as I mentioned, it worked just fine for me. Maybe somebody could provide a bit more "technical" explanation, but that's the best I can do,......harold


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Sunday, October 18, 2015 - 11:33 pm:

Bob - I've done that too, but not necessarily because I really WANTED a fire!


Top of pagePrevious messageNext messageBottom of page Link to this message  By David Dewey, N. California on Monday, October 19, 2015 - 12:57 am:

As a long-term Model A owner (since 1967)I don't se any reason to change it to Negative ground.
Harold, when you hooked up the battery backwards, the diode cut out did it's job and allowed electricity to flow to the generator--because it was the wrong polarity. Once you put the battery in properly, it did it's job in preventing power going to the generator--but! when you motored the generator, you reversed it's magnetic "polarity" so it was producing positive pole voltage, which the diode stopped, as it's supposed to. When you flashed the generator, that allowed it to produce negative pole power, and all was right with the world again--or at least with your model A!


Top of pagePrevious messageNext messageBottom of page Link to this message  By Harold Schwendeman - Sumner,WA on Monday, October 19, 2015 - 04:35 am:

Thanks David - All I know is that what I did per info gained by searching this forum sure got me out of trouble, and you can bet I'll be more careful with such seemingly "simple" electrical wiring connections and battery cables in the future!


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