generator weirdness

[mrkane1952]

Dave:

The function of the "Aux Battery" switch is to bypass the diode and
breaker in the generator battery circuit, to allow the generator
battery to assist the coach batteries start the main engine. Both the
relay in the front and the one in the rear are needed. The symptoms
you describe still suggest a problem with these solenoids, the diode,
breaker, or associated wiring since you have replaced the generator
battery.

There should only be one diode and one breaker in this circuit, which
you found in the rear compartment.

How was the voltage you describe below measured? Let me suggest more
measurements:

1) Measure the voltage from one side of the diode to the other. If
there isn't too much current flowing, it should be 0.7 V.
Alternatively, if the diode is conducting correctly, measuring voltage
from one side of the diode to ground should be the coach charger
voltage--say 14 V--and the other side of the diode to ground would be
13.3 V. The drop (voltage difference) across the diode will be higher
at higher currents.

{The best way to check a diode is to remove it from the circuit and
check it for continuity in the forward direction, isolation in the
reverse direction. Voltage measurements while still in the active
circuit can be confusing due to variations in the voltages of the
batteries and dirty contacts throughout, for example. An accurate
digital meter is also important--I just got a nifty one with the
clamp-on AC Volt feature for about $40 at Sears.}

2) Measure the voltage from one breaker terminal to the other one. If
the breaker is normal (closed,) the voltage should be zero. If not,
then the breaker is suspect.

In my case the front solenoid was faulty in addition to the breaker.
The relay was hot to the touch, even without using the "Aux Batt"
switch, and faulty breaker didn't allow any current from the charging
system to reach the gen battery.

My suggestion at this point is to replace both solenoids and the
breaker, being sure to clean or replace all the connectors, and to
clean the gen battery chassis ground(s).

Good luck--

M.R.
'85 PT40

--- In WanderlodgeForum@yahoogroups.com, "dhardy1944" wrote:
>
> Ernie, M.R., Tom, Don and others,
>
> Thanks again. The pictures from M.R. were a "great" help and looks
> just like my setup. Here is the latest update: According to the
> layout M.R. posted, I have about 13.6 volts at the diode and circuit
> breaker without charger and over 14 volts when the charger is on.
> However, that never makes it to the gen battery unless I push the
> aux switch. At that time the gen voltage jumps to over 14. The relay
> for the aux switch is on a vertical wall just to the rear of the
> front step. But, I cannot see a diode or circuit breaker anywhere
> near it. I am not sure what to do next. I will check our site off
> and on through the day. Rain is coming tonight for the next few
> days, but I should have several hours today. And to Tom, my direct
> reply to your address came back - not sure why. Thanks again to
> everyone.
>
> Dave
>