This seems to indicate that tracking down these pesky electrons is 
tricky business (especially for a novice like me). Here is what I 
know (or rather what I think I know).

I have a master switch that connects the battery to the rest of the 
system (passenger side aft of the seat). I have a switch on my panel 
that turns the alternator on (or so it is labeled). In the past, I 
would turn on this alternator switch after the master switch was on 
and after the engine was running. I looked at the voltage meter and 
would be content to see the needle deflect to the positive side 
making me believe that the alternator was providing a charge to the 
battery.

The radio failure and the battery failure are coupled in time if not 
in causation (if that is a word). With the battery installed that 
has a history of problems, I would get no indication of charging on 
the voltage meter when I turned on the alternator switch.

I swapped the "good" battery back into the system after having fully 
charged it with a trickle charger at home. The engine ticked over 
easily and seem to be very happy. However when I turned on the 
alternator switch, I still got no indication of charging on the 
voltage meter. That may just mean that the battery could not accept 
a charge because it was already charged, or it may mean that I have 
a voltage regulator or alternator problem.

Since my extended checkride is Sunday, I plan to fly the Coupe on 
Saturday. If the radio problem comes back with a fully charged 
battery, I will just use a handheld radio for my test. If it appears 
that I am not recharging the battery in flight, then I will need to 
determine the cause but will probably recharge the battery 
externally just to get me through my checkride.

I probably need better instrumentation on my panel to understand 
when I have a battery or alternator failure and know which is which. 
I noticed a couple of options listed in Aircraft Spruce.

Thanks for all of your comments. This discussion has expanded my 
understanding considerably.

Frank Nelson
N51DV - 415C
TOA

--- In [email protected], "John Cooper" <[EMAIL PROTECTED]> wrote:
>
> >> OK, all, I've hung it out there.  Take your fair pot-shots and 
shoot me
> down if I am wrong.
> 
>  
> 
> Dave is right on the money.  It only takes a couple of volts to 
excite the
> alternator.  (Generators are self exciting due to the residual 
magnetism in
> the show poles, hence the issue of "flashing" the generator.).  My 
comment
> (directly) to Percy was that if there was enough power to run the 
radio
> there was enough to excite the alternator.
> 
>  
> 
> Ercoupes originally all had master switches rather than relays 
that don't
> rely on battery power to operate.  As long as this is still the 
case, the
> battery should charge. Whether it accepts the charge is another 
issue.  If
> the plane has been modified with a master relay then the relay 
must somehow
> get pulled before anything (including the radios) will function.  
Once it is
> pulled the charging system should keep the system operating.
> 
>  
> 
> John Cooper
> 
> Skyport Services
> 
> 4996 Delaware Tnpk
> 
> Rensselaerville, NY 12147
> 
> 518 797-3064
> 
> www.skyportservices.net
> 
>   _____
>


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