I have a 2004 Yamaha 40 4-stroke (Model F40TLRD). I'm trying to figure
out the output that it puts into charging the batteries at various
RPMs. I'm trying to determine how many amps it puts out at idle,
essentially. Does anyone know how to determine this?

On Thu, 15 Jan 2009 06:44:01 -0800 (PST), wrote in
:

I have a 2004 Yamaha 40 4-stroke (Model F40TLRD). I'm trying to figure
out the output that it puts into charging the batteries at various
RPMs. I'm trying to determine how many amps it puts out at idle,
essentially. Does anyone know how to determine this?

Best: Use an ammeter. Perhaps borrow one from an auto shop.

Crude: Measure the charging voltage at the battery over time, and
estimate the charging amps from how long it takes to charge the battery.
This only works well if you know the capacity of the battery (e.g., new
battery) and the voltage regulator is working properly.

--
Best regards,
John Navas, publisher of Navas' Sailing & Racing in
the San Francisco Bay Area http://sail.navas.us/

John Navas wrote:
On Thu, 15 Jan 2009 06:44:01 -0800 (PST), wrote in
:

I have a 2004 Yamaha 40 4-stroke (Model F40TLRD). I'm trying to figure
out the output that it puts into charging the batteries at various
RPMs. I'm trying to determine how many amps it puts out at idle,
essentially. Does anyone know how to determine this?

Best: Use an ammeter. Perhaps borrow one from an auto shop.

Crude: Measure the charging voltage at the battery over time, and
estimate the charging amps from how long it takes to charge the battery.
This only works well if you know the capacity of the battery (e.g., new
battery) and the voltage regulator is working properly.

Yeah an ammeter (ampere meter) would be best but the charging current
will not only depend on the RPM but also of the charged state of the
battery.
boeland