Onan Genset low/no power
Good day all! Day 8 of my first cross country trip in my 1994 Tioga Arrow. I have had a wonderful time. Central Iowa to Tucson and back. Return stops; Amarillo, Thunderbird Lake OK, Table Rock Lake...
Forum Discussion
Badly worn brushes or an open excitation rectifier can cause feeble, flickering lights. This is why I still carry an analog (needle type) AC volt meter. It is impossible for a digital meter to display flickering voltages. Once that issue has been decided, where to go from there? A bad AC line cannot "flicker" without causing sparks and smoke. The excitation circuit (including voltage regulator) can cause flickering. Onan regulators have never seemed to me to have flickered: They either worked or they didn't and when they did they could provide high or low voltage.
A shorted exciter rectifier usually produces steady feeble voltage. Should be noted newer diagnostic type Onans can have dozens of reasons why they do not work right.
But a carbon brush worn to it's extreme limit will provide misleadingly steady power until the instant a load is applied. It can pass a tenth of an amp excitation no sweat but try two amps and it falls on its butt.
Slip rings should be professionally lathe trued and smoothed if the carbon brushes have cut a channel in one or both. If the worn depth of the channel exceeds so many thousandths of an inch the slip ring assembly should be replaced. An out-of-round slip ring will beat the brush and rigging to death.
Brushes that allow flickering can be very hard on the voltage regulator. If brushes are found to be the issue, be sure to run the generator a full load for perhaps 20 minutes to prove the regulator has not been driven squirrely.
Internal brush rigging connections that have gone bad for some reason can also cause this symptom. If you cannot chase the problem down to short brushes, it's time to call a qualified Onan Technician.
A shorted exciter rectifier usually produces steady feeble voltage. Should be noted newer diagnostic type Onans can have dozens of reasons why they do not work right.
But a carbon brush worn to it's extreme limit will provide misleadingly steady power until the instant a load is applied. It can pass a tenth of an amp excitation no sweat but try two amps and it falls on its butt.
Slip rings should be professionally lathe trued and smoothed if the carbon brushes have cut a channel in one or both. If the worn depth of the channel exceeds so many thousandths of an inch the slip ring assembly should be replaced. An out-of-round slip ring will beat the brush and rigging to death.
Brushes that allow flickering can be very hard on the voltage regulator. If brushes are found to be the issue, be sure to run the generator a full load for perhaps 20 minutes to prove the regulator has not been driven squirrely.
Internal brush rigging connections that have gone bad for some reason can also cause this symptom. If you cannot chase the problem down to short brushes, it's time to call a qualified Onan Technician.
