VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 Electrical on a 1928 Chev

I've been working on the '28 for several months, now, been able to put some miles on it, going to shows around... So heres the issue.. Every so often, it will start loosing power, no engine speed, backfiring. I've discovered the main fuse has failed... Not blown. It has gotten hot enough on the source side that it has actually melted the solder connection. My rig has an original amp gauge, always indicates 15-20+ amps and fluctuates wildly. Is this right? Does this indicate a problem?

Any ideas on how it can melt solder but not blow a fuse? The fuses I have been using are 20 or 30 amps.

The car is a pretty much 'vintage speedster'. All my own wiring, minimal body, no top, but does have head/tail/brake lights, and a horn. Aside from the engine, that is about the extent of the electrical system. Uses the original generator.

Any thoughts? I'm not seeing any indications of burn or melt marks on any of the wiring.

Thanks
Rusty

You need to adjust the third brush on your generator to lower the output. Your output of 15 to 20 amps is way too high! The generator output should be down around 8 to 10 amps max.

On the fluctuation of the amp gauge, that indicates that you probably have a weak generator brush spring.

Poor connections of the fuse in the holder allows the fuse/holder to warm up, but still not 'blow' the fuse. The fix is to clean the prongs on the holder and insure the fuse has a nice clean end.


See comment above. Fluctuations are consistent with poor connections as mentioned.

I have only re-wired three 1928 Chevrolets but last time I checked, neither the charging circuit nor the ignition should be wired through the fuse. The only circuits wired through the fuse are the headlights, cowl lamps, tail lamp, and horn. Perhaps you're drawing too much current through your fuse?

Thanks for all of the information, fellows. I really appreciate it. I'll check out the generator, and the connections for that fuse.

All of this wiring is my own, so lots of opportunities to do it wrong.

There is one other thing that I failed to mention. When I checked the points, today, I noticed an issue... No idea if it is a problem but doesn't seem right. On the points, the arm that is fixed to the bottom of the distributor is discolored for the first 3/4 inch. Another case of possibly too much power? Will the recommended changes to the generator address this?

One other question. I put LED lights in the cowl light buckets. Looked terrific for a few minutes. Then both burned out, within a few minutes. I presume that is associated with the generator issue, also???

Thanks again for the support, guys.


Rusty

Is the '28 6V or 12V? I assume 6V if you are using the original generator.

I suspect that your low power problem is due to discovered/burned points.

Since the wiring is of your own design it is difficult for us to help troubleshoot. Melted solder indicates that the joint is getting hot because of a high resistance. The heat created lowers the current on down stream wires.

Maybe speak with a mechanic? Electrical problems are the worst, to be honest. It's pretty interesting how a wire that was corroded or a wire that wasn't connected, can ruin your entire car. I remember that during a tough winter, my cables related to the heat source weren't functioning. It was terrible. I had to call someone from https://bates-electric.com/locations/minneapolis-mn/https://bates-electric.com/locations/minneapolis-mn/ in order to fix the problem, but I don't even want to remember what I have endured during those days. Since them, I am doing my yearly service at an authorized car dealership. I don't want to risk anything haha

Unfortunately, most mechanics are not very good electricians.
Now that everyone is alert, some ideas.
The third brush advice is good.
The brush advice is good.
The fuse advice is good, mostly.

These are primitive systems, so easy to figure out.
You need a voltmeter. An analog voltmeter, to keep an eye on the system.
There is NO other way to be sure, since digital meters are easily confused by the erratic voltages in this sort of system.
Yes, SOME digital meters may work, but you have no way to know which ones and no way to be sure you're getting reasonable readings.

Blowing out your lights is a for sure sign of wrong voltage. Either you used wrong lights or your voltage is way too high.
If your cutout is sticking, you can massively overcharge OR short the battery back through the generator and maybe ruin both!

The hot fuse indicates high currents, as stated.
But a fuse in the charge lead IS a good thing, to protect against a bad cutout, as above.
The point arm burning also indicates excess current. I'm surprised you haven't eaten the coil.

SO, what to do?
STOP DRIVING, before you destroy coil, generator, lights, and/or battery.
GET an analog voltmeter or multimeter. Cheap, $20 range, because you'll likely blow it up.

https://www.tequipment.net/ElencoM-1250.html?Source=googleshopping&/?utm_content=analog%20multimeter&utm_term=&utm_campaign=Shopping%20Campaign(BSC)&utm_source=Bing_Yahoo&utm_medium=cpc&msclkid=c6085432a1271f1067e534180377fe26

The Ohms scales are handy, if you learn to use them.
A plain voltmeter from a car parts store would do what you really need first. MANY are stupid expensive, but I think you can find it under $10.

The real answer is an electronic regulator, but I don't know if they are available.

Once you can measure voltage and confirmed your cutout is not sticking, then you are ready to set your third brush for reasonable voltage, with your loads turned on.
A diode is a MUCH better cutout than the originals!

The cutout is where I'd start, with the brush setting backed off all the way.
Then bring the brush up to get some current, while measuring the voltage.

As I said, you're dealing with a primitive system. It will overcharge in the day and hold even at night, depending on how you set the brush.
Batteries tolerate a little overcharge, so you just have to get a happy medium where you survive at night and don't charge too heavily in the daytime.
You're actually better off setting for night and driving with the lights on all the time, unless you never drive at night.

Mounting a voltmeter under the dash is a very good idea! They make brackets for that.]
The voltmeter should have it's own wires going to the battery + and - terminals, so you don't get mixed up measuring with voltage drops in wires or bad ground connections between body parts or between body and engine and battery.

You are WAY out in the weeds, but it's not hard to get back...
WL

Actually... good mechanics ARE good electricians. If they aren't... they aren't good mechanics. :-)

Also, I really don't see what the cutout has to do with whether or not the system is overcharging. All it does is close when the generator is producing enough voltage to charge the battery, and open when it isn't. It really doesn't care how high the voltage goes, that's not it's job.

In other words... a sticking cutout can not in itself cause massive overcharging of the battery.

And... isn't this thread kind of old?

Yes Ole!

This is almost 7 years old. I figure that by now his speedster is running great or burned to the ground. Or is is someone else's problem!

Never too old to get us talking.
Read more carefully. I covered a lot of ground.
No, the cutout can't cause overcharging, but it CAN fail to open and short the battery to ground through the armature of the generator, if it's failing to open.
Overcharging is a third brush problem, as stated by others.
WL

I won't argue that your advice makes sense. Just wondering if the original poster even cares that we are trying to help him.

I think his last post was 2015 but the info recently posted is still interesting. I think any post over a year old with no activity should be locked Possibly anyone interested in the same subject could start a new thread and could always reference the old post.

I respectively disagree with locking old threads and starting a new one just to add more information about the same topic.

Just because the post is old doesn't mean that the content is no longer correct.

It is better to keep all the pertinent info together so when someone searches for it, they find more info in one place.

My two cents, Dean

Dean your point is well taken. I agree keeping all the pertinent info in one place would be best but I have no idea how that could be accomplished with the present Chat set up.