Help - Dino charging problems again

Hi

I keep getting this problem re-occuring and need some help from the tekkies amongst us.

Here is the problem

Ignition Off - Battery voltage 12.72v
Regulator term 15 -0v
67- 0v
Fuse box (firewall) 8amp fuse 0v
60amp fuse 12.70v

Ignition On Battery voltage 12.42v (fuel pump running only)
Reg term 15 11.75v
67 11.52v
Fuse box 8amp 11.38v
60 amp 12.30v

1000rpm Battery voltage 13.99v
Reg term 15 13.99v
67 14.16v
Fuse box 8amp 12.60v
60amp 13.97v
2500rpm Battery 17.19v
Reg term 15 17.20v
67 16.75v
Fuse box 8 amp 16.46v
60amp 18.45v

Obviously this is serious as the large red cable on the firewall gets very hot

I have a suspicion that the battery has a dud cell as the battery doesnt hold its charge for any longer than 2-3 days max unless i keep the trickle charger plugged in.

I remember John posting something on this subject in that the alternator is working overtime as it isn't seeing the filed voltage. It appears the voltage is rising on increase in rpm when it should actually be decreasing. I have changed the voltage regulator, but before i invest in another battery i would like to know what is causing the problem before i fry a new one.

All earth connections have been checked and appear good, fuse connections and terminals also cleaned to ensure a good contact.

Any ideas?

Tony

PS when i released the battery top up screw, pressure was released!!!!

 

Tony - nice presentation. Data is helpful.

Whether the battery was the culprit or the victim, it appears that it will need to be replaced. It may well have a bad cell which is looking like a short circuit to your charging circuit. That's why the large red wire on the firewall is getting hot.

The voltage regulator is working overtime, and not correctly. When charging, the battery should achieve about 13.8 volts. Your data at 1,000 RPM is perfect. However, as you increase the revolutions per minute, and the voltage on the main bus increases, the voltage measured at Terminal 67 should decrease. The increased speed of the alternator (and magnetic lines of flux intersected per unit time) should put out more current, raising the system voltage. The regulator should adjust accordingly and decrease the field current (Terminal 67) to decrease the output. This is not happening.

I cannot tell from the data where the culprit is. However, as your battery will not hold a charge, and you are pouring current into the battery, it sounds as though two plates in the battery have collapsed and are touching each other. By the way, what does you amp meter read?????? This is very important. I suspect that it is showing a large charging current. Correct? If this is the case, then the alternator is doing what you ask of it (or at least what the regulator is asking of it).

I would approach the problem by 1) first changing the battery. Relatively low cost, and always a good idea if the battery is old anyway, 2) recheck your data, 3) if things have not improved, buy an inexpensive 3-wire off-the-shelf regulator for a Honda 1970+, or Toyota. They are all the same, do the same thing, and are far less expensive than the Ferrari version. You can test with the 3-wire solid state from the Japanese manufacturer, and then rule-in or rule-out the regulator component. Go down to a local auto supply shop, look through their voltage regulator book, and pick one with 3 wires - Plus +, Field F, ground.

Hope this helps.

Jim S.

 

Thanks Jim for another informative post.

You are absolutely correct that the ammeter is showing a full (max) charge so thankfully i am spared the task of pulling the alternator out!!

The regulator is brand new Jim so i am at loss to suspect that this is the problem. Although i have fitted a mechanical one, i am tempted tochange to a solid state. I can second guess what John C would say on the mechanical reg.

Tony

 

Tony - first change the battery. The original Ferrari Magnetti regulator is an electronic (transistor) device. The 70s era 3-wire from Honda or Toyota are also electronic. They typically cost around $30 U.S. If changing the battery does not fix the issue, the regulator swap is rather easy and inexpensive.

I would not run the engine too long with the alternator being flogged to produce 40+ amps. Can't be good...hot internal wires and diodes.

Jim S.

 

Jim, The 60amp red wire on the fusebox gets very hot after about 5 mins. Advice taken.

The odd thing is that a few weeks ago the field wire on the 8amp fuse was showing a decrease in voltage on rising rpm. The thing that startled me the most was when i released the battery top up screw to inspect battery electrolyte level. It was like letting down a balloon.

I hope its the battery!!

Tony

 

Hello,

Just one thing: Is this problem new or has it been going on for a while?

When I rebuilt my alternator, I did not wire it back properly. There is a connection on the alternator that should be left alone. If you connect the field wire to it (which I did), you will overcharge as the regulator can no longer do what it is supposed to.

Double check your wiring on the back of the alternator.

I hope this helps

 

Thanks for the tip, i did rebuld the engine last year but i am not sure when i got the problem. It always charged high for a short while and the ammeter always bounced around then seemed to settle down!!

I will check this as you kindly suggested.

Also one other thought was that the recon alternator i bought a few years back may have the voltage regulator built into it, not sure now and the supplier doesnt know either...great. Was hoping that i didnt have to pull the alternator out as you all know its a real swine of a job.

I will change the battery first of all as this is the easy bit.

QUESTION . If i need to drive it, can i pull the 8amp firewall fuse to stop it overcharging (the red cable is almost melting when i run it about 5 minutes) will it burn out the diodes?

Tony

 

Tony - if you need to run it for 5 minutes or so, take out both fuses on the firewall. You will be running on battery alone. Given that you battery is in a poor state of health, who knows how long it will keep the ignition alive.

If your red wire/fuse on the firewall is that hot, then something is wrong. The only comforting knowledge is that there is a fuse in the circuit that should blow at 60 amps. However, if you look at the 60 amp fuse, I am not sure how well one can calibrate that hunk of wire bridgeing the gap in the holder. Change your battery, determine whether your alternator has a regulator (unlikely if it is a replacement for the Dino), and regroup.

Jim S.

 

Thanks Jim

My reckoning is that the 60amp fuse is more like 100amp. The wire did go soft and very hot, it should have blown it really

Keep you posted!

Tony

 

Well i got the battery tested and it was defective, bought a new one and fitted it. Unfortunately it didnt cure the problem!!!!

i disconnected the field wire on the voltage reg and get 14v, checked ammeter and no charging. tested the field wire from the alternator and i get 16v, reconected field wire and i get 16.9 volts across the battery terminals.

Any ideas what and how you can test the alternator in the car. (havent checked terminals yet)

 

The voltage regulator is nowhere near as complicated as the owners manual discusses diodes, voltage conditioner, etc, etc. It is simply an electromagnetic switch with a threshold at about 14.6 volts that shuts off charging above that to prevent the battery from overcharging. For you to acheive higher voltage than that is very interesting and highly irregular.
Here's how I tested mine
http://www.ferrarichat.com/forum/showthread.php?t=193757

The stock alternator fuse boxes are now quite rare and expensive. I went to a high end mobile stereo store and for $20 USD bought a proper 60 Amp fuse and holder. The spade pins fit the Dino connections exactly and you can be sure that this modern replacement will trip if overpowered. Modern one has O-ring seals to keep out dirt and moisture.
Best of all it is easy fitted and takes seconds to revert back to the original if you want to show the car.
Here is how I did it:
http://www.ferrarichat.com/forum/showthread.php?t=189438

Electrically stressing the wiring and components to the point that they get very hot can not be good.

 

Tony - I need a bit more information. You measured 14 volts at the regulator when disconnected....was that at the terminal of the regulator (Field) or on the end of the wire that was attached to the terminal??? If at the terminal of the Magneti red box, then this is too high for a 16.9 volt battery voltage.

When you mention that the ammeter revealed no charging, was that when the Field wire was disconnected. And finally, 16.9 volts measured at the Field wire from the alternator? Was that the same wire as where you got 14 volts?

Scott is on the right track...the regulator is not a mystery. It is a feedback control system. It senses battery voltage (+ terminal), and when low, it convinces the the alternator to generate more current by raising the Field voltage. Hence, there is an inverse relationship between battery voltage and Field voltage. When battery voltage goes down, Field voltage should go up. When you increase RPMs, the alternator puts out more current, and as the battery voltage increases, the regulator senses this and decreases the Field voltage, bringing everything back to normal.

Normal battery voltage while the engine is running should be about 13.8 volts, and the field current around 8-10 volts (if I recall correctly). As the battery voltage drops (as when the engine idles and lights are on) to 12 volts or less, the Field voltage will increase to 11 volts or slightly more. Unlike the old Lucas units, this is not an all-or-none phenomenon. It is a continuous feedback system, so voltages rise and fall continuously. The old Lucas units were a relay that switched on and off.

Now that you have a good battery, I suggest that you head down to a local auto store, thumb through their voltage regulator catalog, and purchase the least expensive 3-wire Japanese (Honda, Toyota, etc.) of 1970s vintage unit. It will have 3 wires; +, ground, and Field. Simply connect these terminals or pig tails to your 3 wires under the dash, and give it a try. If everything works, tape it up and drive away. When you feel wealthy again, buy an original Magneti unit for Concorse purposes. There are people (I have done it) that rebuild the old Magneti's. Not difficult.

Finally, your battery may have failed as a result of overcharging. The voltages that you present suggest that the Field voltage is too high, and a good alternator would overcharge the battery.

Jim S.

 

Thanks for your help on this so far

I disconnected the field wire from the voltage regulator and started the engine and left it ticking over at 2500rpm.

The ammeter showed no charging.

Measured white wire voltage from alternator (that connected to VR) and this read 16 odd volts

Measured terminal on VR and this was 14 volts

Reconnected wire to VR and voltage reading was 16v

As you say its a very simple circuit, as i understand it, the voltage regulator measures battery voltage (green wire 15)and if it falls below 12v it increases the field voltage (white wire 67) to the alternator to make it start charging the battery via the 60amp red wire on the fuse box. When it has topped up the battery to the preset voltage it reduces the field current to reduce the charging output from the alternator.

It seems to me that the alternator is overcharging the circuits. i need to ascertain where the increase in voltage is coming from......i think!! Its a barnd new VR of the mechanical type so i dont think the problem is there.

Question:- can a faulty short circuited ignition coil have an effect on this?

I will definately take your advice on upgrading the fuse box. It could have done a lot of damage to the wiring harness.

Will do some more testing later on

 

Another thing to do while you are into it at this level, measure the current drop across all the fittings and connections you access, to be sure there is not some significant phantom resisitance. Use the millavolts scale of your VOM and measure every connection from wire to terminal (don't open the connections), terminal to fuse etc and so on, any high readings should be cured. Really high readings (requiring the 5 volts scale to read would be a big problem.

 

Where are things on this?
LOTS od included data, and some opinions-what EXACTLY is the complaint.
A preventative procedure foe all DINOS-connect a manually installed shunt line on the back of your ammeter.
LOOK carefully at your wireing diagram...the internal shaunt fails frequently-sort of a when not an if-and will wreek havoc with the charging circuit, rot batteries, and toast the fuse panels...yadda, yadda, yadda, do this 1st, THEN see what happens...a really common complaint/problem here....

 

355s - can you explain in more detail what the common fault is?

The EXACT fault is that the charging circuit overcharges the battery. At 2500rpm i get over 16v across the battery terminals and the red cable from the alternator to the fuse box is almost melting!!

Tony

 

355s - Would you please explain this internal shaunt (sic) that you are referring to? I have carefully looked at the wireing (sic) diagram and I simply can't find it. And I am not certain that it will wreek (sic) havoc if I can't find it. Can't be that common a complaint can it, albeit, you suggest that it fails frequently, this internal shaunt (sic). Thirty-five years of driving three Dinos, and it has never failed in one of my cars. I agree, however, that Tony should feel the ammeter to make sure that it is not hot owing to loose terminals on the back...a common problem.

Michael Bayer is correct in his concern for aged contact corrosion (oxidation) and increased resistance. The Dino is particularly susceptible to this issue, as the mechanical layout calls for a rather long run from the alternator to the regulator. Significant contact resistance (at three points) can lead to a false-low field voltage at the alternator. This will result in the main-bus voltage being low, regulator field voltage rising, and a positive feedback loop....not a good thing.

I suggest that you remove all terminals at 1) the firewall fuse box, 2) the voltage regulator, and 3 the regulator fuse under the front bonnet, and clean them with fine sandpaper. Remove the fuses and clean the ends and the clips that hold the fuse.

Tony - a short in the coil can lead to problems, but the circuit is fused. Furthermore, the car would not run.

Clean the contacts just to eliminate this as a problem. You mention a mechanical regulator....could you elaborate on this? The red Magneti is a transistorized unit.

And, the LOTS od (sic) data that you provide is quite helpful.

(355s - having fun...took me a while to figure out what your post was saying. Actually, an interesting puzzle.)

Jim S.

 

Jim / Scott

I fitted the electromechanical regulator on a test rig similar to your set up as everything pointed at the brand new VR. Applying different voltages on terminal 15 didnt seem to make it do anything,you heard a small click but the changeover switch remained static which allowed the varying applied voltages at 15 to be seen at terminal 67 as well.

Bearing in mind this is a brand new VR, i decided to adjust it by slightly tweaking the spring tension.

Redid the test and the higher voltages over 12v started to be reflected a reduction in terminal 67 field wire

Refitted to car and tested.

tickover i got 12.69volts across battery, increased rpm and got 13.50v across battery increased to 3000rpm and got 14.6v with 4.0v on terminal 67.

turned on all lights and battery voltage stayed at 14 volts but field voltage increased to 8v

Seems to be working OK to me.

Now to change those fuses, certainly a modification ALL dino owners should undertake

Thanks for taking the time and effort to help out.

 

Tony - Great job! It's fun to take something apart, analyze it, and make it right. Really good outcome.

While changing the fuses to modern equivalents is certainly an option, I have chosen to simply clean them with sand paper and brake clean to rid them of oxidation. It is important to clean the conical end of the old plastic fuses, and to clean the seats where the conical end sits (on the copper fuse clips). I have found that simple attention to this detail will result in significant reduction in contact resistance and improved electrical performance.

Anyway, an interesting problem, diagnostic path, and solution.

Jim S.

 

Thanks guys and as i said, i appreciate your help.

What worries me is what could have happened had i not become suspicious of the ammeter needle stuck on the right hand side. Clearly the 60amp fuse is never going to blow before the cable would have melted.

May consider fitting a 50amp fuse and carry a spare!! Easier to change than the wiring loom!

Cheers

Tony