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Old 09-01-2019, 03:00 PM   #1
John Dayhuff
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Default 700 RPM's ??

I want to check the charging of my generator with a meter and was told that it should be at a "high idle" of 700+ RPM's. Without a timing light how else would I know if I'm up to speed or not?


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Old 09-01-2019, 03:20 PM   #2
Patrick L.
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Default Re: 700 RPM's ??

Does your ammeter show a charge when the engine speed is up ? What charge does it show ?

Is this a stock factory system ?

2-3 amps is fine for daytime driving while it could be bumped up to 5-6 amps if driven at night fairly often. I wouldn't be concerned about the exact engine speed, as long as you raise the engine speed and it then shows a charge it should be fine.
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Old 09-01-2019, 03:23 PM   #3
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Default Re: 700 RPM's ??

get a cheapie tach dwell meter,it uses the point impulse to measure engine speed
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Old 09-02-2019, 01:10 PM   #4
John Dayhuff
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Default Re: 700 RPM's ??

Yes the car is pretty much stock ,including the six volt battery/generator system. At a fast idle I'm getting 7.8 volts at the generator and 6.8 volts at the terminal box, is this normal? The third brush is turned all the back. My amp meter on the dash says minus 4 amps at a slow idle and plus 4 amps at the faster idle speed. Could this lower amperage mean my battery is being drained? Why does it go so low at times? The amp meter is a reproduction 20/20 meter however.


Thanks or the tach advice, I'll look into that.


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Old 09-02-2019, 01:46 PM   #5
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Default Re: 700 RPM's ??

Here is what I use, inexpensive. Only one lead wrapped around the coil/plug wire about 2-3 wraps, programmed for 4 pulses. Has internal battery. The lead is long enough to mount inside, a lot of inexpensive battery tachs have short leads, not long enough to mount it inside the A. There is a backlit version available. Updates every 1/2 second or so.


https://www.amazon.com/Trail-Tech-74...s%2C225&sr=8-1
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Old 09-02-2019, 02:46 PM   #6
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Default Re: 700 RPM's ??

At very low idle approx. 400- 650/700 rpm, the generator is basically not working, this is normal.


The 3-4 amp discharge you see is mostly for what the A needs to run the ignition. Typically you do not sit at this rpm very long, and when the generator starts charging at higher rpms the generator charges/refreshes the battery for the current/power supplied by the battery during that time of low rpms.


Same Is true of using the starter which presents a huge temporary load on the battery when starting. You do not see this load since the starter does not go through the ammeter. But since the starter is a temporary load, the generator refreshes the battery at a lower current to charge the battery back to full charge.


I am rusty on electrical, but believe the battery, generator and terminal block should always match voltages. You possibly have poor connection(s). Check/Clean the: battery post connections, battery to frame connection, starter/start switch (large and smaller wires) connections, generator/cutout relay connections, Terminal block connections, remove the instrument panel and check the ammeter connections.
Make sure to clean to bare metal, and check that crimps are tight.
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Old 09-02-2019, 02:57 PM   #7
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Default Re: 700 RPM's ??

Yes, you should have the same voltage at the terminal box and cutout terminal as they are directly wired together. The ideal charging voltage on a 6V system is around 7.2V, 7.8 isn't bad. I believe in some Ford literature the headlights are referred to as 6-8V so you'll be good to go once you figure out why your terminal box voltage reading is low. Like 30CCPU said, check the wire end crimps. There have been multiple posts about how they can work loose and cause all sorts of weird problems.
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Old 09-02-2019, 04:20 PM   #8
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Default Re: 700 RPM's ??

Thanks guys for all the great info. I'll work on that and report back on it when I can.
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Old 09-03-2019, 02:54 AM   #9
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Default Re: 700 RPM's ??

All wire harness terminals should be soldered, and not just crimped.
At 500 engine RPM the generator is running 750 RPM and my battery is being charged.
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Old 09-03-2019, 07:00 PM   #10
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Default Re: 700 RPM's ??

So I go out to start the car yesterday and it can't hardly even turn over like the battery is dead again. UGH!! I'm heading out for a new battery ASAP.


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Old 09-03-2019, 07:09 PM   #11
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Default Re: 700 RPM's ??

Check those grounds. Do you have a separate ground to the transmission?
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Old 09-03-2019, 08:45 PM   #12
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Default Re: 700 RPM's ??

Not that I know of.
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Old 09-03-2019, 09:00 PM   #13
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Default Re: 700 RPM's ??

Quote:
Originally Posted by Tom Wesenberg View Post
All wire harness terminals should be soldered, and not just crimped.
At 500 engine RPM the generator is running 750 RPM and my battery is being charged.


Went out and checked my truck, -2 amps at 500 motor RPM. At 700 rpm amp meter is at 0 amps. When truck is off, at 0 amps. Lights on truck off, -3 amps (have LED head lights).


Generator is a new rebuilt this year from Berts. At 1000 rpm charge rate is 6-8 amps with lights/etc off. Can not get lower charge rate, 3rd brush is adjusted full up.


My generator must somehow act differently than yours. I do not know what is normal. Perhaps mine is abnormal?
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Old 09-04-2019, 02:09 AM   #14
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Default Re: 700 RPM's ??

As the battery ages, or if it's too small, it is less able to control the generator output. When I first bought my 29 Tudor, the 6 volt battery was shot, so I jump started the car on a 12 volt and drove it around on the worn out 6 volt, but I couldn't get the powerhouse generator to regulate less than 12 to 15 amps. A new battery took care of that.
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Old 09-04-2019, 05:45 AM   #15
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Default Re: 700 RPM's ??

I would recommend checking for a draw and then check/remove/clean the battery ground connections.
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Old 09-04-2019, 06:15 AM   #16
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Lightbulb Re: 700 RPM's ??

Put a free spectrum analyzer or frequency meter on your phone and set the idle to 23.3hz at the exhaust.

700 revolutions per minute x 2 exhaust pulses per revolution divided by 60 second equals 23.3 pulses per second or 23.3hz.

Science
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Old 09-04-2019, 07:43 AM   #17
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Default Re: 700 RPM's ??

Better yet, put a voltage regulator in and forget about the generator AND the battery. It'll take good care of them.
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Old 09-04-2019, 07:51 AM   #18
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Default Re: 700 RPM's ??

A voltage regulator is a good idea and I like the one Tom W makes.
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Old 09-04-2019, 11:09 AM   #19
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Default Re: 700 RPM's ??

Yep, I use Tom Wesenbergs voltage regulator as well. You can't go wrong. Charges around 1A under most circumstances, even running down the road with the stock 50cp headlights on. Just put it in this year and I think my 8 year old battery gave a sigh of relief.
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Old 09-04-2019, 03:50 PM   #20
John Dayhuff
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Default Re: 700 RPM's ??

Voltage regulator?? Talk to me Tom!!


I checked the battery without the terminals hooked up and I got 5.8 volts. I can't remember what it was at the starter but I want to say about a volt less? I'm taking the battery to Auto Zone where I bought it a year ago to let them test it and go from there I guess.
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