That's not the problem though. It's putting out 16V, which I suspect
will fry the little U1 battery.
RWL

You mean that with the engine running you measure the voltage across
the battery and it reads 16 volts?

Yup. With the engine off, the battery reads something like 13.6V
freshly charged, and once the engine's running the voltage across the
battery terminals is 16+V

I phoned Onan today and have an inquiry in regarding what I should be
seeing. The secretary said the tech who knows that information was
gone for the day, but she'd get back to me tomorrow.

RWL

On Thu, 17 Feb 2011 22:00:51 -0500, GeoLane at PTD dot NET GeoLane at
PTD dot NET wrote:



That's not the problem though. It's putting out 16V, which I suspect
will fry the little U1 battery.
RWL

You mean that with the engine running you measure the voltage across
the battery and it reads 16 volts?

Yup. With the engine off, the battery reads something like 13.6V
freshly charged, and once the engine's running the voltage across the
battery terminals is 16+V

I phoned Onan today and have an inquiry in regarding what I should be
seeing. The secretary said the tech who knows that information was
gone for the day, but she'd get back to me tomorrow.

RWL
Put 2 silicon diodes in series with the battery to drop 1.4 volts,
giving you the ideal 14.6.

5 amp 25 volt should do.

On Thu, 17 Feb 2011 22:00:51 -0500, GeoLane at PTD dot NET GeoLane at
PTD dot NET wrote:



That's not the problem though. It's putting out 16V, which I suspect
will fry the little U1 battery.
RWL

You mean that with the engine running you measure the voltage across
the battery and it reads 16 volts?

Yup. With the engine off, the battery reads something like 13.6V
freshly charged, and once the engine's running the voltage across the
battery terminals is 16+V

I phoned Onan today and have an inquiry in regarding what I should be
seeing. The secretary said the tech who knows that information was
gone for the day, but she'd get back to me tomorrow.

RWL

Yes, that is a bit high. Do you have a wiring diagram for that engine?
If so can you locate where the alternator is getting exciting voltage
from and see whether there is a way to put a resister or regulator in
the line to control the output.

Have a look at http://homepower.com/files/webextras/mark8.pdf
it is not your specific problem but it does tell you how to control an
alternator.

On Feb 17, 10:00*pm, GeoLane at PTD dot NET GeoLane at PTD dot NET
wrote:
...
Yup. *With the engine off, the battery reads something like 13.6V
freshly charged, and once the engine's running the voltage across the
battery terminals is 16+V
...
RWL

Try a known-good battery.

jsw

Put 2 silicon diodes in series with the battery to drop 1.4 volts,
giving you the ideal 14.6.

5 amp 25 volt should do.

I did that today. I had the original diode and a 10A diode. It
didn't change it even 0.5 V

I think I'm going to buy a voltage regulator and be done with it. If
I were better at electronics, I'd build one. I recall reading about
the circuit and there's a specific (transistor?) that's a voltage
regulator and the output is biased with a resistor to produce the
desired voltage. A pretty simple circuit from what I remember
reading, but it's a long time ago.

RWL

On Fri, 18 Feb 2011 08:24:41 -0800 (PST), Jim Wilkins
wrote:

Yup. *With the engine off, the battery reads something like 13.6V
freshly charged, and once the engine's running the voltage across the
battery terminals is 16+V
...
RWL

Try a known-good battery.

The battery is brand new and I charged it before attaching it to the
generator.

RWL

GeoLane at PTD dot NET wrote:

Put 2 silicon diodes in series with the battery to drop 1.4 volts,
giving you the ideal 14.6.

5 amp 25 volt should do.

I did that today. I had the original diode and a 10A diode. It
didn't change it even 0.5 V

Your test probes should be on the battery terminals
themselves. Is that how you are taking your readings?
Placing the test probes on the clips attached to the
battery can sometimes provide false readings.

--Winston

On Feb 19, 10:56*pm, GeoLane at PTD dot NET GeoLane at PTD dot NET
wrote:
On Fri, 18 Feb 2011 08:24:41 -0800 (PST), Jim Wilkins

wrote:
Yup. With the engine off, the battery reads something like 13.6V
freshly charged, and once the engine's running the voltage across the
battery terminals is 16+V
...
RWL

Try a known-good battery.

The battery is brand new and I charged it before attaching it to the
generator.

RWL

Give the freshly charged battery a day's rest for the surface charge
to dissipate, then it should measure 12.6 to 12.8V. You could
discharge it to 12.0V and then check the charging voltage.

I opened a Harbor Freight $3 multimeter with a blown 0.5A current fuse
and found a calibration pot, so I set up an adjustable 12.000V
reference and calibrated some meters. The pot is quite sensitive but
can be set so the meter alternates between 11.99 and 12.00 within
about 5mV of 12.000V. I marked the pots before turning them and can
barely see a difference. So far the worst one was off by 0.05V before
adjustment.

One yellow meter reads the same with a fresh or discharged 9V battery.
The battery connectors are too flimsy to risk testing all of them

jsw

On Sat, 19 Feb 2011 20:31:27 -0800, Winston
wrote:

GeoLane at PTD dot NET wrote:

Put 2 silicon diodes in series with the battery to drop 1.4 volts,
giving you the ideal 14.6.

5 amp 25 volt should do.

I did that today. I had the original diode and a 10A diode. It
didn't change it even 0.5 V

Your test probes should be on the battery terminals
themselves. Is that how you are taking your readings?
Placing the test probes on the clips attached to the
battery can sometimes provide false readings.

Putting the ammeter between the two battery terminals would fry the
meter. I had one lead attached to the cable and the other to the
battery terminal. That's how I could tell the battery was receiving a
1.5 A charge.

RWL

GeoLane at PTD dot NET wrote:
On Sat, 19 Feb 2011 20:31:27 -0800,
wrote:

GeoLane at PTD dot NET wrote:

Put 2 silicon diodes in series with the battery to drop 1.4 volts,
giving you the ideal 14.6.

5 amp 25 volt should do.

I did that today. I had the original diode and a 10A diode. It
didn't change it even 0.5 V

Your test probes should be on the battery terminals
themselves. Is that how you are taking your readings?
Placing the test probes on the clips attached to the
battery can sometimes provide false readings.

Putting the ammeter between the two battery terminals would fry the
meter.

Or open it's fuse. The context of my comment was a voltage
measurement, though. The symptoms you outline are consistent
with measuring the charging circuit without a solid connection
from voltmeter to battery, or an 'open' cell in the battery.

I had one lead attached to the cable and the other to the
battery terminal. That's how I could tell the battery was receiving a
1.5 A charge.

That is proper use of an ammeter.
If we are seeing only 1.5 A into the 12V battery while providing
16 V across it, I suspect the battery is dead. Open circuit.
No Longer With Us. Pining for the Fjords.

--Winston

On Fri, 18 Feb 2011 21:23:28 +0700, john B.
wrote:

On Thu, 17 Feb 2011 22:00:51 -0500, GeoLane at PTD dot NET GeoLane at
PTD dot NET wrote:



That's not the problem though. It's putting out 16V, which I suspect
will fry the little U1 battery.
RWL

You mean that with the engine running you measure the voltage across
the battery and it reads 16 volts?

Yup. With the engine off, the battery reads something like 13.6V
freshly charged, and once the engine's running the voltage across the
battery terminals is 16+V

I phoned Onan today and have an inquiry in regarding what I should be
seeing. The secretary said the tech who knows that information was
gone for the day, but she'd get back to me tomorrow.

RWL

Yes, that is a bit high. Do you have a wiring diagram for that engine?
If so can you locate where the alternator is getting exciting voltage
from and see whether there is a way to put a resister or regulator in
the line to control the output.

Have a look at http://homepower.com/files/webextras/mark8.pdf
it is not your specific problem but it does tell you how to control an
alternator.
I suspect it is a permanent magnet "alternator" with a "shunt"
regulator (usually combined with the diode rectifier) so has no
external sense.