Charging system troubleshooting question

Arlen Johnson · Mar 29, 2020

L.A.B. said:
The ammeter connection between the 'battery negative terminal' and the 'cable' mentioned in the test should be the brown/blue harness wire, not the starter motor cable or don't use the electric starter.

In order to do the 'DC input to battery test' exactly as the manual dictates, so I get accurate results, I need a 1 ohm resistor, so I ordered a couple 1 ohm, 100 W wire wound resistors from amazon for $11. They won't arrive until Wednesday.

L.A.B. · Mar 29, 2020

Arlen Johnson said:
In order to do the 'DC input to battery test' exactly as the manual dictates

The resistor is for 'Testing the alternator in situ'.

Arlen Johnson · Mar 29, 2020

L.A.B. said:
The resistor is for 'Testing the alternator in situ'.

Thanks! I guess I need to pay closer attention. I canceled the order for the resistors for now. Now I'll do the
'DC input to battery test'.

Arlen Johnson · Mar 29, 2020

Arlen Johnson said:
Thanks! I guess I need to pay closer attention. I canceled the order for the resistors for now. Now I'll do the
'DC input to battery test'.

I get about 2.5 amps at 1000 RPM and 1.1 amps at 3000. It seems to me it should be the other way round.

L.A.B. · Mar 29, 2020

Arlen Johnson said:
I get about 2.5 amps at 1000 RPM and 1.1 amps at 3000. It seems to me it should be the other way round.

I don't know but 1.1 amps at 3000 RPM is more than the "0.5 Amp minimum".

Arlen Johnson · Mar 29, 2020

L.A.B. said:
I don't know but 1.1 amps at 3000 RPM is more than the "0.5 Amp minimum".

So can I conclude there is nothing wrong with the charging system?

Arlen Johnson · Mar 29, 2020

Arlen Johnson said:
So can I conclude there is nothing wrong with the charging system?

If I keep the same connections for the 'DC input to battery test' and switch the VOM to DC volts, shouldn't I see the voltage pushing electrons into the battery? And as long as it's in the neighborhood of 13+ volts doesn't that further indicate the charging system is doing its job?

L.A.B. · Mar 29, 2020

Arlen Johnson said:
So can I conclude there is nothing wrong with the charging system?

Well, not if what it says in the manual is correct, however, it doesn't seem to agree with your original findings (below) unless there was a bad connection?

Arlen Johnson said:
Third test:
- Engine at 3000 RPM
- Voltage at power outlet =~ 12.5 V

Conclusion:
The battery isn't getting charging voltage (above 14, or so). In fact, the voltage at the power outlet goes down with the engine running. I assume the voltage at the battery is also about the same, 12.5 V.

Arlen Johnson said:
If I keep the same connections for the 'DC input to battery test' and switch the VOM to DC volts, shouldn't I see the voltage pushing electrons into the battery? And as long as it's in the neighborhood of 13+ volts doesn't that further indicate the charging system is doing its job?

Reconnect the wire and test (DC volts) between the battery terminals.

Arlen Johnson · Mar 29, 2020

L.A.B. said:
Well, not if what it says in the manual is correct, however, it doesn't seem to agree with your original findings (below) unless there was a bad connection?

Reconnect the wire and test (DC volts) between the battery terminals.

Before starting the engine and right after disconnecting the battery from a trickle charger there were 13.25 volts across the battery terminals. With the engine running it dropped about 1/2 volt. It didn't matter what RPM; the voltage stayed the same.

Charging system troubleshooting question

Arlen Johnson

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Arlen Johnson

Arlen Johnson

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Arlen Johnson

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