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6 volt generator charging system in question


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Newer battery with good clean solid connections in the electrical system. Trickled charged over night. Good strong start and off we go for an hour cruise. Voltage gauge shows charge at start and kind of peters down during cruise. Shows discharge at stop lights especially when turn signals are on. Maybe this is normal? Stop at ice cream shop after the hour cruise. Ready to disembark and engine turns over very very slowly almost not starting at all. Slower than I would expect. Car finally does catch and back home we go. I'm questioning the charging system at this point. All I've done so far is charge the battery back up, start the car and hook my multi-meter to the battery. Meter reads around 6+ volts. Increase rpm's and meter reads 7+ volts....but here's what I see. The meter drops to 4, 3 and even 0 for a split second then back up to 6 or 7. Like there's intermittent breaks in the charging. Does this raise an immediate flag to anyone? I have a pretty detailed article on testing the generator and voltage regulator and plan to do so, unless someone might know what this fluctuation could be. Thanks! 

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It sounds like your system is operating correctly. You will see charging while driving until the battery is fully charged, then it will gradually taper down to 0. 0 or a negative reading at idle is normal and it should pop back up once you accelerate, top off the battery, then drop back down to 0 again. Totally normal. Generators don't put out much amperage at low speeds (or high speeds) which is why everyone eventually switched to alternators. However, if your battery is healthy, it won't mind the brief periods of discharge and it should have plenty of reserves so that you never have a problem.

 

The regulator uses points to control generator output. It's either on or off, so it modulates output by rapidly opening and closing the points depending on the amount of charging required. It will not be a linear function, so the bouncing around you are seeing is normal. If you want, you can read up on proper adjustment of the voltage regulator and make sure that's correct, plus clean the points inside the regulator, but irregular spikes like that aren't unusual during charging.

 

The re-start problem sounds like the typical hot start problem that many 6V cars have. If you improve your grounds and make sure they're all clean, install heavy (like 00-gauge) battery cables, and perhaps add an extra ground cable from one of the mounting posts on the starter to the frame near where the battery is grounded, things should improve. As heat goes up, so does resistance, so hot starts can be a problem for cars where the electrical systems are marginal. A lot of 6V cars are running parts store 12V battery cables, which are much too small. Grounds get dirty and rusty and nobody checks them, so resistance goes up. Both are critical for a 6V system to be reliable and strong, and the fix is inexpensive and easy.

 

Your system isn't broken, it's just a little bit neglected. Big, new cables, clean grounds, and a healthy battery will make it start every time. Good luck!

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1 hour ago, Matt Harwood said:

If you improve your grounds and make sure they're all clean, install heavy (like 00-gauge) battery cables

 

The car came with 1 gauge positive cable and one of those braided negative cables. I'm a stickler for clean connections so those are impeccable. Guess I can replace those and look at the regulator next. 

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Run more grounds. From the engine to the frame and from the frame to one of the posts on the starter. Make sure there's no paint or rust on the connections. For your ground strap in the photo, did you scrape off paint on the block before connecting it? That little bit of resistance can make a difference. More grounds can't hurt and might help quite a bit. I had a car that was impossible to start hot. I had some custom 00 cables made, added a ground strap from the battery post to the frame near where the battery was grounded, and made sure all ground connections were shiny metal sealed with dielectric grease. That car started quickly hot or cold no matter what after that (you probably don't need two Optimas like I used--I was turning over a giant V12).

 

Battery1.thumb.jpg.8c68d45178d055911109ae6cb2c89e85.jpg  Ground1.thumb.jpg.bfd36513613a7d6d4659989711c32a51.jpg  Ground2.thumb.jpg.8af3f50d4fc7d45c86113d792f1b434a.jpg

 

StarterMount1.thumb.jpg.b00bb08130133c0963f3500a7c8542a3.jpg  Ground3.thumb.jpg.a826c557791905d298eb744ae5116a1f.jpg

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6 minutes ago, Matt Harwood said:

For your ground strap in the photo, did you scrape off paint on the block before connecting it?

 

Yes, to a shiny metal. Awesome idea, thanks for the thoughts and pics!

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As for that braided negative cable, what gauge would that be? I tried searching but only came up with info on 4 or 2 gauge. That's too light IMO. I just got off the phone with a shop that can make me new 2/0 cables. I love the look of the braided but it's either that or r--r-rr--rr-rr.....(that's the sound of the engine cranking over slowly)

Edited by Summershandy
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I dropped off the original cables at the shop and noticed pre-made 2/0 cables with lugs on the shelf. I'll try these new thicker battery cables first and see how it performs. If need be, I can pick up another ground cable or two and install as suggested. 

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Voltage regulators regulate by vibrating points. It is normal for the voltage to have a little instability. I'm surprised you can see it going to zero though. What kind of meter are you using? My digital ones freeze up when I try to use them on my 6V Pontiac. If you can actually see what the voltage is, check it against the book. It might be low. I suspect it should be around 7.5 volts, but check the manual.

 

Generator systems don't charge much at idle, if at all. Thats normal.

 

I see you have an original style battery. You can check that with a hydrometer to see how charged it is. It will also show you if one cell is not getting charged as much as the others. That would indicate a battery defect.

 

If the battery is just not getting fully charged, turn the voltage regulator voltage up 0.2v from where it is and drive it a few days. Then, check it again. Driving habits matter with generator systems. A guy who idles in traffic a lot will need a higher setting than someone who drives mainly on the freeway in daylight.

 

Edited by Bloo (see edit history)
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A good charged up 6V battery should run and start the average midsize 6 cyl inline easily normally, several times a day, even without ANY generating, unless you're running lights, heater and radio full blast, OR unless you/ve got a big heavy V8..

I know this because I've run these on nightly battery chargups when I couldn't come up with he money for generator work until next payday (and maybe not then)...just get home before full dark...

If a big V8, as mentioned in earlier posts above, hot hard starts are not unusual when everything's not tip=top, and sometimes even then...my brother was a longtime member of the Cad club, had several prewar Cads, and sometimes just shrugged at slow hot starts...

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1 minute ago, gregchrysler said:

run a jumper cable to the positive side of the starter and the other cable to either the negative battery side  or a good ground then u will know if it s the wiring

Best to express this technique in terms of GROUND terminal rather than assuming which terminal (positive or negative) is grounded.  So run a VERY heavy duty (jump start cable) from the grounded battery terminal to a starter mounting bolt to test.

 

For best results, remove starter, clean paint (and crud and corruption) from face of starter case and its mounting, and from both sides of the ear of the starter with the most accessible mounting bolt, then run a supplemental 00 cable from battery ground terminal to the starter mounting bolt.  I usually cover that connection with a bit of ignition grease to deter future corrosion.

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Thanks for all those suggestions guys! When I got the car just over a year ago, I had the shop bench test/inspect both the generator and starter. Both were good. I've since cleaned up the solenoid for a better start. I made sure all wiring and end connectors were in tip top shape. Made sure to clean up where the starter mounted for a good ground. I should be getting my new battery cables today. I'll be sure to update any changes.

20 hours ago, Bud Tierney said:

my brother was a longtime member of the Cad club, had several prewar Cads, and sometimes just shrugged at slow hot starts...

 

Guess I'm just not familiar with slow hot starts. I didn't get the car on the road until late last summer and never really had the chance to drive it often or get a real feel for it. This year I am. 

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You have to find out why the voltage drops to 4,3 then 0.  This is not normal. After you sort out all the wiring from the battery and starter, check all the wiring in the charging system.  Wiggle every connnection to the generator and regulator.   If all good, then I suspect the regulator or possibly a weak cell in the battery may be the culprit.  L

Let us know what you find.

Joe, BCA 33493

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Now THAT'S what I'm talking about! Went for a short cruise on a hot day. Excuse my electrical ignorance but, does moving to heavier cables and extra ground help charging as well as hot starts? I swear the gauge is acting different. When I take off from a stop it goes heavy in the charge zone. While cruising it actually sits half to a needles worth in the charge zone. It never did this before. Restarts are waaay faster and stronger. What I would expect. I have to admit, I always thought I had "sufficient" sized cables that came with the car. I see now the PO before me just bought regular battery cables from a retail store. Whether this is all my imagination and helps the issue or not, I'm happy knowing I've given the electrical the best it wants. Also want to admit even though I'm a back yard mechanic, I've never used dielectric grease even though I always make sure connections are clean. Thanks to everyone for egging me on to do this!

IMG_7884.thumb.JPG.1668bcb15615d9419517da11d016cf15.JPGto 

 clean contact area at starter finish with dieletricIMG_7885.thumb.JPG.582cb16f772cf670cfd1877bf27c8198.JPG 

likewise at frame

 

 

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The finished product. I'm also happy with the new cables as the post lugs are much smaller and I had a fear of the positive grounding out on the cover. Best $100 spent!

 

IMG_7891.thumb.JPG.9e200671a9621ff82375d28a261dc7da.JPG

 

Install new 2/0 cable. It was longer than I liked at first, but considering all the linkages and moving parts it worked out quite well. Doesn't hang too low either. 

 

IMG_7888.thumb.JPG.696dc514dba48f489874bbf2ff99b66d.JPG

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2 hours ago, Joseph P. Indusi said:

If all good, then I suspect the regulator or possibly a weak cell in the battery may be the culprit.  L

 

I'm still considering removing the regulator for inspection. It's definitely been replaced recently but not by me. Battery I bought new last year.  

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2 hours ago, Joseph P. Indusi said:

You have to find out why the voltage drops to 4,3 then 0.  This is not normal.

 

Joseph, I may have had the meter on the wrong setting from the original post....I checked the battery again and it's at 6.25 volts while idling. My bad, I always get those settings wrong!

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Yes, heavy or the right size cables helps starting and charging also.  You can buy an inexpensive battery hydrometer and check each cell to see if the specific gravity of the electrolyte  is OK for each cell.  A fully charged lead acid cell should have a SG of about 1.28.  A simple alternative would be to charge the battery for a few hours and then turn on the headlights for 6 seconds and then turn them off.   Place a digital voltmeter across the battery terminals and you should read 6.3 volts with one cable disconnected from the car. 

Glad to see you are making progress.

Joe, BCA 33493

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OK, just read your last post.   6.25 volts at idle is good depending on the engine RPM at idle.   As I said in my previous post, a fully charged battery, with no current draw (one cable disconnected) should read about 6.3 volts.   If your battery is fully charged, typically after a 10-15 minute run at speed, the voltage across the battery at above idle, 1200 RPM or so,  should be about 7 to 7.5 volts.

Your charge indicator behavior seems to be correct for a good battery and charging system.

Joe

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59 minutes ago, Joseph P. Indusi said:

6.25 volts at idle is good depending on the engine RPM at idle.

 

The idle speed for these straight 8's are 365 - 385 rpm. When I pick up the idle I get in the mid 7's like you mention. 

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On my Pontiac, yes. On Summershandy's I see the negative cable goes straight to the block rather than the frame. That lessens the importance of the third cable somewhat (but it does still need to be good).

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This is great news! You should celebrate this moment; it doesn't always work out this way with old cars. Rarely are things as they seem, even given obvious circumstances. I can't tell you how many times I've had a problem, found an obvious cause for said problem, fixed it, and had the problem persist anyway. Maddening.

 

All the upgrades you've done there should last a long, long time and build confidence in the car. It's a wonderful feeling to be able to get in and know that it will do what you expect it to do, regardless of the weather. Little things really do make a difference!

 

Happy motoring!

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Grounding to the block to the battery doesn't always translate to a chassis ground.

I had a customer once that was getting sparks at his throttle foot feed when his headlights were on,  Might have had them with lights off as well but never noticed.

Engines and trannys are all mounted on rubber.

Most electrical problems are 'groundless'.

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16 minutes ago, Matt Harwood said:

This is great news! You should celebrate this moment; it doesn't always work out this way with old cars.

 

Tell me about it brother! I still have little wrinkles I keep trying to iron out even though I go through the steps in repairs and fixes. Still, I read a lot that if this isn't your thing then maybe one of these cars aren't for you! Always something around the corner I say. 

 

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18 hours ago, JACK M said:

That cable from the frame to block (starter) may be the most important cable in the car.

 

 What Jack said!  One can never have TOO much ground. Perhaps more than need, but never too much. 

 

 Example.  I owned several Semi Tractors [ trucks ] in my driving career. One , back in  the early 90s was an Autocar. I was replacing lighting circuit toggle switches every month or so. They would just fail. One day, while messing with the electrics, i grabbed onto a ground from the cab [ body ] to the starter mounting bolt. Almost blistered my fingers, it was so hot. I had an 00 ground cable made and installed .  Never replaced another toggle switch in 12 years.    Can not have too much ground.

 

  Ben

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As far as the multi meter dropping to 0 and then to 3 and 4,   are you using a digital meter?    The digital meters  often do funky things as the  voltage changes.  A good old meter with a needle is best.

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14 minutes ago, Pete O said:

are you using a digital meter? 

 

Ya my first meter that's digital....and probably a cheap one at that!  No one ever learned me how to use one. I wing it from YouTube! I did find a bad spark plug once on an old motorcycle though. That was helpful. Was also using it to check the car battery. Luckily, I haven't had any real electrical issues. 

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I know i'm a little late to this party, internet issues. You have to be careful when using digital meters on vehicles with mechanical points. Such as ignition, voltage regulator and relays. Digital meters can be very sensitive and overreact to the opening and closing of the points. Making you think you have a severe voltage fluctuation. Whenever I am setting a mechanical regulator on my bench I use an analog meter. Cost does not matter I have seen Fluke brand meters with this issue. Put your meter on your daily driver fluctuation most likely will not be seen. 

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3 hours ago, certjeff1 said:

I know i'm a little late to this party, internet issues. You have to be careful when using digital meters on vehicles with mechanical points. Such as ignition, voltage regulator and relays. Digital meters can be very sensitive and overreact to the opening and closing of the points. Making you think you have a severe voltage fluctuation. Whenever I am setting a mechanical regulator on my bench I use an analog meter. Cost does not matter I have seen Fluke brand meters with this issue. Put your meter on your daily driver fluctuation most likely will not be seen. 

 

It either works or it doesn't! As you mentioned it often doesn't, thats why I asked the question. Digital meters don't work at all on my 36 Pontiac. The good ones (Fluke, Tektronix) just lock up. Analog VOMs work fine, but generally don't have the resolution you need to set up a voltage regulator. Not everyone has an Allen or Sun generator test set laying around..... I am currently building an analog meter just for this purpose.

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Also have a 6V system on the 26 Rover 9. Initially I also saw wild readings with a DVM on the generator output, up to 10V,  but after cleaning the cutout points the readings became stable and sensible, so I question the idea that DVM are not usable on mechanical point systems. Its only a cheap DVM, nothing fancy.

jp 26 Rover 9

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I'm glad thats working for you.

 

When I bought my 1936 Pontiac, I tuned it up, and attempted to set the timing with my trusty old Snap-On dialback timing light. It didn't work, just locked up constantly. I opened it up and didn't find anything obviously easy to fix, so I went out and bought a new Bosch dialback timing light. It locked up. I kept trying, and I think I have killed the Bosch. When I last tried it on another car, it wouldn't even light up. Later on, I figured out the Snap-On is not broke, it works fine on other cars.

 

The car has oversize headlight bulbs because the correct ones are not available. I thought I had better monitor the charging voltage, because I am not sure if the tiny generator can keep up, and also to see if the regulator was set correctly. First, I bought a cheap digital panel meter on ebay and temporarily hung it under the dash. A drive across town blew it to smithereens. Several tiny surface-mount resistors inside the cheapie meter were open. It did not look repairable.

 

Next idea was to use a DMM. It is much harder to keep track of while you are driving compared to a lighted display, but I own some good DMMs, so I gave it a shot. I tried a Fluke 8060a (two of them actually), a Tektronix TX-3, a circa 1991 Radio Shack meter, and a Harbor Freight cheapie. None would work for more that a few seconds. The Tektronix behaved bizarrely even after having it's batteries pulled out, but came back to life a day later (whew!).

 

To check the advance curve of the distributor, I needed a tachometer. Normally I would just use the Snap-On timing light, as it has a tachometer built in. An old Sears basic timing light (no dialback or tachometer or anything) seemed to work. I bought MSD timing tape, and a digital photo-tachometer at Harbor Freight. The photo-tachometer locks up in close proximity to the Pontiac, and will not work. It isn't even electrically connected. As it turns out it works fine on other vehicles. I used it on a tractor 2 weeks ago.

 

YMMV

 

 

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On 7/15/2019 at 8:44 PM, Bloo said:

 

It either works or it doesn't! As you mentioned it often doesn't, thats why I asked the question. Digital meters don't work at all on my 36 Pontiac. The good ones (Fluke, Tektronix) just lock up. Analog VOMs work fine, but generally don't have the resolution you need to set up a voltage regulator. Not everyone has an Allen or Sun generator test set laying around..... I am currently building an analog meter just for this purpose.

 

Nothing better than a Fluke meter, you just need to buy the good one.......1200.00 Fluke is shielded from everything. I bought mine back in the 80’s and still works great.  I can run a 16 Cadillac without interference on the meter. Try that with one of the Harbor Freight units.

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  • 2 weeks later...

I made up my own battery cables with 00 welding cables. Mat and other guys on this forum gives good advice.  While the engine is running use a small jumper and ground the field  somewhere on the engine. By doing so you will be bypassing the regulator. If voltage shoots up then look for the  problem in regulator. Do not hold the ground for long as this could burn up the generator. If the generator is on the bench use a heavy jumper and feed some juice to the field wire . If the generator is good it will  spin. A slow spin is an indication of problems inside. May be worn brushes and filings. I would replace the regulator  because the points may be pitted. Best to remove it , place it on the bench and clean and reset them. Some regulators have adjuster screws for the points and in some a pliers is needed to bend the tabs. I am subject to correction here. When the car is started the amp meter should start pumping out about 12 to 15 amps and gradually drop to near zero as the battery juice is built up. when accessories are turned on the generator will increase it charge to keep up the battery . I think a fully charged battery should be about 7.6 volts. A battery reading 6 volts  or a 12 volt battery reading 12 volts is half charge or there about. There are so many variables to check.   

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