DB26

Questions on Testing 1926 DB 4 Cylinder 6 Volt Generator

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Posted (edited)

Hello everyone, I’m not a complete novice at electrical theory, but am no expert. I have a question / questions about testing the 6 volt charging system.

 

Ive read the mechanics instruction booklet on the subject and it talks a lot of amperes and cut outs, but I’m still not certain my system is charging correctly. 

 

Using a multimeter with the engine OFF, my battery reads about 6.12 volts.

 

Whith the engine running at idle it reads only 6.11 volts. 

 

My experiece with late 50s fords leads me to believe there is a problem. 

 

I know the manual says the charging system cuts in at 9 MPH, but I would think racing the engines throttle would give me the same result. 

 

It it did not, constant 6.11 volts across the board. 

 

The amperes meter is one the sweeps from 12 to 12, so it might be the incorrect one. The needle stays on zero mostly, and dips backs forth very subtlety. 

 

Does anoyone have advice on how to properly test the charging system on my 26 Dodge? It appears it’s never been adjusted or tampered with. I have a spare cut out a I can swap in. And the fuse is good. 

 

Thanks everyone , and Happy 4th of July to my fellow citizens of the USA! 🇺🇸

Edited by DB26 (see edit history)

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Do a search on 3 brush generators and their adjustment , pretty straight forward.

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The generator output voltage has to be greater than the battery voltage for the cut out relay to close and charge the battery.  If the generator output is weak due to brush wear or the third brush is not properly adjusted the cutout relay will not engage.  That is the simple place to start, after that it gets a little more complicated.

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 Do not start the engine ,I repeat do not start engine for this test  . If you take the wire coming out of generator to cut-out ,off the cut-out . Then hook 6 volt battery charger to that cut out terminal . Be aware of your polarity . The 7. something voltage from the charger should close cut-out and show on charger amp meter and with voltage reading at battery . This shows condition of everything cut-out continuity of wire and fuse  to battery . If that good then generator is problem . Remove and start bench testing .

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10 hours ago, ArticiferTom said:

 Do not start the engine ,I repeat do not start engine for this test  . If you take the wire coming out of generator to cut-out ,off the cut-out . Then hook 6 volt battery charger to that cut out terminal . Be aware of your polarity . The 7. something voltage from the charger should close cut-out and show on charger amp meter and with voltage reading at battery . This shows condition of everything cut-out continuity of wire and fuse  to battery . If that good then generator is problem . Remove and start bench testing .

Good info.  I need to print this and keep it with my D2 as engine startup time gets closer.

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I would have all of the electrical parts checked by a competent rebuilder prior to installation to stave off any issues later on. Ounce of prevention is worth a pound of cure!

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Very true what Jpage says . The test only show it works . Not how it will function under load or vibration . Found myself to have intermitted problem that was weak rivet connection at amp meter , and then loose fuse holder and then bad switch . But my dash was also exposed to water damage, so was not surprised by .

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On 7/5/2019 at 7:47 PM, ArticiferTom said:

 Do not start the engine ,I repeat do not start engine for this test  . If you take the wire coming out of generator to cut-out ,off the cut-out . Then hook 6 volt battery charger to that cut out terminal . Be aware of your polarity . The 7. something voltage from the charger should close cut-out and show on charger amp meter and with voltage reading at battery . This shows condition of everything cut-out continuity of wire and fuse  to battery . If that good then generator is problem . Remove and start bench testing .

Thank you! I will do this test very soon. 

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I did the test of the cut out. It doesn’t cut “in” until around 10 volts. A problem? It does reach the battery cables, and with a multi meter connected there I receive the same 10 volts. So continuity seems OK 

 

I have a second spare cut out and I bench tested that one. That one cuts “in” at around 8 volts. 

 

Thoughts? 

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I’ll probably be removing the generator this weekend and making sure everything is clean and not worn out. 

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Better but still a little high . Did you try cleaning points . Use paper and alcohol or contact electric clean . Do not sand or file , unless pitted . What ever surface silver or gold will be removed . They will wear out quicker then .

 Was that 8 with it hooked to battery and it's wire circuit . You may find that to use up some of your voltage and add load to coil to pull in sooner . Make sure all connections and surface mounts are clean of paint . after done can be touched up .

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The 10 volt test on the car was done with no battery connected. 

 

The 8 volt bench test was done with only the cut out, no other wires connected to it. 

 

Thanks for telling me about not sanding the points, I just ordered a new points file, won’t be here until tomorrow. Glad I haven’t done it yet. 

 

I will clean points and retest. Should I do the next test with the battery hooked up? 

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Please .  You must always have battery in circuit . It affects how the generator charges . You risk it going over charge and ruining armature . I have heard they can go wild ,as high as 40 volts . Newer regulators adjust generator out put like third brush and monitor it on amperage with constant voltage rate . These beast charge based on voltage . One reason battery service was so important in the day .

     I put one of those electronic voltage regulators (EVR)'s  on mine this Spring . It is internal and working great . No more under or over charge conditions or dim lights .

     Good job 26 .

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I just remembered something, a while ago I was driving and had forgotten to tighten my negative battery cable. It fell off while driving and my engine completely died. Is this any indicator of a good or bad gen?

 

I was poking around some other posts and some some other members wrote of making a curcuit with a diode to replace the cut out? Is this similar to what your voltage regulator does? 

 

 

Thank you for your input. I will report back after I have done some more poking and prodding. 

 

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1 hour ago, DB26 said:

I was poking around some other posts and some some other members wrote of making a curcuit with a diode to replace the cut out?

 

 

I have seen using the original cut out housing and modernizing it with a diode inside...thereby keeping the"look" original. Was totally custom and not off the shelf. Worked and looked fine.

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Yes, Diode will work better then cut-out . Maybe should say safer . Cut -outs , I read , are prone to sometime fail close thus bleeding battery power back to generator causing the small wires between to heat up like hot plate coil and caused fires . This is why you always watch the amp gage after shutting down engine to make sure contacts opened . If closed will show . draw or discharge . The amp gage is a great tool of  diagnosis on your engine . Dropping needle to zero could mean bad fuse , wiring , connection  or opening ignition coil , sometimes intermittently .

   The small size container or Delco cutouts make the diode heat sinking harder . So as said above most are custom jobs unlike Fords being made as off shelf . You will find these kits in Ford restor parts books and maybe ebay , quit cheap . Macungie and Hershey are around corner both should have .

   I have a kit ready if mine gives up the ghost ...

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3 hours ago, ArticiferTom said:

Yes, Diode will work better then cut-out .

 

And will last a lifetime, since there are no moving parts.

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The generator came off today...

 

I feel stupid for not seeing this before, but the fuse on the cutout is blown! I’m still glad I removed the generator for cleaning, and overall analysis, but am feeling a little embarrassed over not seeing this problem. 

 

I’m assuming since the fuse blew, it means the generator was indeed charging?

 

I wonder if it blew when my battery cable disconnected itself while driving? Does that seem like a plausible scenario? 

 

I will report back during the week with pictures of my findings. 

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Here are some photos I took today. Here is the cut out. The points are misshapen, but open and close.

 

CF0137D3-54B4-4CB3-B6C0-EFC34489CCFE.thumb.jpeg.a8bb172cbf5ed942eefab48ec9cc16ee.jpeg

 

E1C45EA0-8BDB-46DC-AA99-C25752E282FB.thumb.jpeg.5c859cd832dbb62d267e4897f7cfa8c8.jpeg

 

02095806-2FFD-4BBD-8909-F3F9FEFD34E6.thumb.jpeg.174836127129193fd6e96b212a036814.jpeg

 

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The bearings feel great, still nice and smooth, and the brushes appear to have a lot of life left in them. One even still show the North East part number. The commutator looks decent to me as well. 

 

FFE0B4C2-176E-4307-B6BB-77D085A815C3.thumb.png.cfd8d349a176610273c4710f935866d9.png

 

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Here are some more brush photos, springs have good tension:

 

BD8AB31E-F3C0-41A6-A621-A85D7A143631.thumb.jpeg.3e1e014df47e9188dfbe470ea6f6e453.jpeg

 

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71182EC5-E876-49D7-9DA5-94133BEFBD27.thumb.jpeg.b6d239e55968271be8b7c33e48f76def.jpeg

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Posted (edited)

The armature looks alright except for some flaking material at the top near the commutator. Should I worry about this?

 

543AA906-0859-4627-9B79-8AF4552F15E9.thumb.jpeg.ad7f7bb0f10e2e129845aa408dfa3e9d.jpeg

 

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Edited by DB26 (see edit history)
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And lastly, here is a shot of the underside of the windings:

 

7C123B43-64C0-45C0-9C03-6F8B40B081DA.thumb.jpeg.46deebc5235e20508cbc36c1ab8183a9.jpeg

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