charging question?

[Anonymous-0]

Me Again, what should my 12 volt system read on the ammeter when running? how many RPM's does it take to show a considerable charge? I don't think my system is charging right, the meter only reads at the "0" or at the most +2 to 3. I am thinking that it should read higher than that if it is really charging. Is this an altenator issue?

as always,

Shawn

 

[ZANE]

When the engine is started it takes a lot of the charge out of the battery. The alternator is capable of replacing this spent charge back into the battery in just a short time. Minutes. When the battery is back fully charged all that is being drained is the ignition so the alternator voltage regulator reduces the amount of amperage that is being sent to the system and that is the small amperage you see. It should read 10 to 20 Amps just after the tractor is started and then drop back pretty quickly with an alternator.

Zane

 

[Dean]

Shawn:

The current output of a properly operating charging system will depend upon the load upon the electrical system and the state of charge of the battery.

If your battery is fully charged, little output is needed from your alternator and the ammeter will show little or no charge.

If you look at the ammeter immediately after cranking the engine you should see a larger positive deflection of the needle for a short time.

Dean

 

[dennisinoklahoma]

My Jubilee and 8N tech manuals state the 6 volt generator should start to put out current at 1250 rpm and have a full 20 amp rate at 1650 rpm.

The amount of current flowing through the ammeter will depend on how well charged the battery is. As the battery reaches full charge, the difference in voltage between the generator output and the battery decreases. As this happens, less current will pass to the battery because it has less of a voltage differential to drive the electrons.

If you are not having any starting or dead battery problems, you are probally fine.

If your battery goes dead, charge it up and take it in to have it tested under load.

According to the tech manual, an easy way to check the generator is to jumper between the armature and field terminals on the generator. Start the engine and note the ammeter reading. While running remove the jumper and the ammeter should show more current than before.

A more complicated home grown way to test the charging system as a whole without using a voltmeter is to turn off the key and run the starter for 20 seconds, let it cool, run it again, and then wait awhile and repeat the process. A new starter should be rated for 90 seconds without damage but these old starters are a lot weaker. Leave the lights on to help drain the battery. Then start the engine and see how much current is passing through the ammeter with the battery partially run down.

Of course, it could be a faulty ammeter that shows a lower current than it should.

 

[DanH01]

Ditto what Dean and Zane wrote. I did see a post on here once that said that because these engines run at such low RPM"s that they really don"t start charging till you have the RPM"s in the mid-600"s.(abt half throttle or less). That does make some sense. If you"re jumping a car with a dead Bat. you always rev the jumper car to get the dead Bat. to charge quicker. Anyways the readings you have are fine. One way to see this in action is to turn on your lights(if you have them) while watching your gauge. The needle should jump then settle back to the middle. Dan

 

[Dell (WA)]

Shawn.......remember, yer amp-meter is a 20% device, meaning it is only 20% accurate. But yeah, a fully charged battery only needs about 3-amps trickle charge while running. And depending upon how and where the ammeter is wired into the circuit it may never show how much yer alternator is outputting, just how much is going into and outta the battery.

Yer 12-volt alternator with built-in voltage regulator is fully charging at about 600rpms. (1/4-throttle) But that is what the voltage regulator does, cuts-down or boosts-up the alternator output depending upon the charge condition of the battery.

And NO, the ammeter don't care, positive or negative ground; don't care 6 or 12-volts. Just what goes "thru" the ammeter is all that is measured. .......Dell

 

[FLAcharlie]

When my '50 8N is happy, when the alternator first kicks in, it shows maybe 10 amps, which quickly (within just a couple minutes) declines to 3 or 4 amps the rest of the time it's running.

 

[Bruce (VA)]

Re-read his post. He has an alternator.
50 Tips

 

[JMOR]

(quoted from post at 00:25:24 10/27/09) Re-read his post. He has an alternator.
50 Tips

Isn't is incredible, Bruce, the answers people post that are in no way relevant to the situation?!!!
It is as though they have a thought that pops out without any connection to the question being asked.........just plain weird?

 

[GunPilot]

Put a voltmeter on the battery when it's running. If you see 13 volts or so, you are good to go.

 

[Anonymous-0]

Guys, thank you for your input. I will be sure to check the listed items.

Shawn

 

[Bruce (VA)]

Yep. Some answers are not relevant & others are just dead wrong.

Next time I see a question about "charging" I think I'll make reference to Lord Tennyson & the Light Brigade.