Summershandy

6 volt generator charging system in question

Recommended Posts

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! 

Share this post


Link to post
Share on other sites

check voltage regulator     and cca on battery  they go bad after 3 years     and check grounds and wire gauges   and connections on starter

Share this post


Link to post
Share on other sites

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!

  • Like 4

Share this post


Link to post
Share on other sites
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. 

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites
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!

Share this post


Link to post
Share on other sites
Posted (edited)

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
add on (see edit history)

Share this post


Link to post
Share on other sites

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. 

Share this post


Link to post
Share on other sites
Posted (edited)

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)

Share this post


Link to post
Share on other sites

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...

  • Like 1

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites
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.

  • Like 1

Share this post


Link to post
Share on other sites

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. 

Share this post


Link to post
Share on other sites

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

  • Like 1

Share this post


Link to post
Share on other sites

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

 

 

  • Like 2

Share this post


Link to post
Share on other sites

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

  • Like 3

Share this post


Link to post
Share on other sites
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.  

Share this post


Link to post
Share on other sites
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!

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites
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. 

  • Like 3

Share this post


Link to post
Share on other sites

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

  • Thanks 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...