Guys,
Just to keep you up to speed as to where were I'm at.
Tonight before it got too dark I managed to check the following with
the engine at 2200 rpm's. At first after charging Battery, the voltage
check direct on the terminals was 12.5. The GG alternator inputs on
the regulator we're 15.7 AC so I'm assuming the engine is producing
correct voltage. I checked the +B out of the regulator and it read
only .55 volts DC. Moved the engine up to 3000 RPM's and the +G only
went to .55 volts. One of you said that should be 13.5 which is what I
thought to charge the battery. Keep in mind my regulator is brand new.
Just put it on because I thought the old one caused the problem.
Turned all lights on and everything on the direct reading on the
battery went to 11.8 volts DC. After about 7 to 10 min. that went to
11.5
I can only feel at this point the new regulator is bad and that the
main loose ground I had found last week may have caused me to believe
the old one was bad. What are my chances of buying a new regulator
thats bad? Is there any other reason anyone can think of that may
cause the +B regulator output to be only putting out a half of volt?
Your inputs are very welcome!
Jeff R. N128LJ Gold Rush. Should have taking that shop course on
electronics 40 years back.
On Apr 8, 2010, at 5:12 PM, Greg Fuchs wrote:
> >
>
>
>> ...
>> What is the battery voltage when the engine is running?
>> You can also disconnect the regulator from the battery, BUT KEEP THE
> CAPACITOR CONNECTED TO THE REGULATOR! and run the engine (preferably
> with
> all avionics switched off) and measure the voltage across the
> capacitor.
>> Voltage for the standard Rotax regulator should be appr. 13.7 Volts.
>> Let me know how this works out so we have a starting point.
>
>> Frans
>
> Jeff,
>
> These are good points from Frans. Just an additional comment. IF
> this is a
> shunt regulator (I think it is), it regulates by shorting out the
> alternator
> phase(s) to ground, once the voltage starts to go higher than its
> internal
> setpoint (lets say somewhere around....14-15 volts or so, at the
> regulator).
> If there is no load to the alternator such as accessories and a
> battery, the
> regulator has to soak up ALL of the excess power from the
> alternator. At
> high engine speeds, this can become very significant. Without
> cooling, it
> can be very hard on the regulator. I suggest that if you test (yes,
> DEFINITELY with the capacitor) without the battery hooked up, try
> not to run
> the engine too high in rpm for too long so as not to risk damaging the
> regulator. IMHO, test with battery in circuit if possible, unless the
> battery itself is suspected. A charge voltage between 13 and 14
> Volts I
> consider good, and 13.8 ideal. Anything over 12.7 is charging the
> battery
> (for lead acid technology).
>
> Your battery tested at 12.5. That means its about 84% charged,
> assuming it
> is newer and in good shape (or the reading would be higher), does
> not have
> any significant load connected to it, or charged within a half day
> or so of
> the reading (voltage reading will be high after a charge, but slowly
> drop to
> its normal value). If it had measured 12.7V, it would be fully
> charged.
> 11.94V would have signified about 10% charge. No-load checks are not
> the
> best way to check a battery and these values only work for lead-
> acid, but it
> gives an idea of its charge status. This paragraph is just a bit of an
> aside, but might help if wondering about charge state of the battery
> or
> battery diagnostic. If only one cell is bad in the battery (for
> example,
> shorted plates), the battery would read low by about 2.1V. Assuming
> a fully
> charged, it would be below 10.6V for the voltage reading. If it has a
> cracked post, its value won't seem to make sense every time you
> measure it
> ...charging....loaded....just sitting there... and it will drive you
> (I mean
> me) crazy. Good Luck!
>
> Regards,
> Greg
>
>
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