I appreciate much has been written before about generators and voltage regulators but can a circuit voltage of 15.3volts in flight after 1 hour be caused by anything other than a poory adjusted voltage regulator ?
Following charging problems we replaced the battery,the 20A generator and the voltage regulator 5 months ago but last week the engine would not crank.
The battery was charged off the aircraft and on subsequent flights the circuit voltages have been checked using a Garmin Pilot 3 GPS plugged in to the cigar lighter.
At the start of the flight the voltage is 14.7V with radio and anti collision beacon on.This drops to 13.9V with the VOR and DME on as well.
After 1 hour airborne the voltage rises to 15.3V with the radio and beacon on and 15.0V with the VOR and DME on as well.
Only the pitot heat or landing light will get it to reduce to about 13.0V
Another feature is at the start of the flight the generator lamp goes out at 1300RPM at 11.9V but after a 1 hour flight it does not go out until 1500RPM at 12.3V.
Thanks
Bryce
Circuit Voltage 15.3V
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
Bryce, the voltage observed at your cigar-lighter outlet can vary considerably depending upon several things. The contact point at the tip of your GPS's power plug is notoriously capable of high-resistance and poor contact. As a result, it's voltage sampling can vary not only from flight to flight, but from moment to moment, due to vibration, corrosion of the original lighter socket contacts, metallurgical/electrolytic differences between the steel socket contact and the GPS chromed tip of the plug,...the list goes on. (And the variances you've observed with the various electrical loads/appliances are simply indicators that the system is working normally withing the parameters of the design. It's not uncommon to see the voltages you've described with such systems energized.)
Top all that off with the 50-year old wiring and connections that may exist within your electrical system,...and you'll get the idea.
You might also consider whether or not you have a more recent design, digital/electronic voltage regulator or an older technology "original" type vibrating-points regulator.
As far as your antiquated storage-battery is concerned.... it doesn't much care if you charge it with a modern digitally regulated current or not. It is such a crude method of storing DC electrical current (it's actually a chemical storage battery, designed to convert chemical reaction to electrical energy) that the actual type of regulator is not that important,... But an original style, vibrating-points regulator can vary in actual voltage from 13 to 15 volts or so on every flight. It can be dependent upon the quality of the ground-circuit of the regulator, that of the battery, and that of the generator.... and it can be affected by temperature, and even the residual magnetism of the stamped sheet-metal cover of the regulator itself!
The point is, that with the digital readout of your GPS, you are back to the old analogy of "measuring it with a micrometer, marking it with a grease-pencil, and cutting it with a hatchet" type of operation.
In any case, the running voltage of your system being anywhere between 13 and 15.3 volts is not the reason your battery was discharged previously. You will need to find a different answer to that difficulty.
And in the meantime, do not spend a lot of time or money attempting to regulate your generator any more tightly than 13-15 volts or so. Your battery simply doesn't care.
In other words, with the information you've given, I do not see a problem with your charging system.
Top all that off with the 50-year old wiring and connections that may exist within your electrical system,...and you'll get the idea.
You might also consider whether or not you have a more recent design, digital/electronic voltage regulator or an older technology "original" type vibrating-points regulator.
As far as your antiquated storage-battery is concerned.... it doesn't much care if you charge it with a modern digitally regulated current or not. It is such a crude method of storing DC electrical current (it's actually a chemical storage battery, designed to convert chemical reaction to electrical energy) that the actual type of regulator is not that important,... But an original style, vibrating-points regulator can vary in actual voltage from 13 to 15 volts or so on every flight. It can be dependent upon the quality of the ground-circuit of the regulator, that of the battery, and that of the generator.... and it can be affected by temperature, and even the residual magnetism of the stamped sheet-metal cover of the regulator itself!
The point is, that with the digital readout of your GPS, you are back to the old analogy of "measuring it with a micrometer, marking it with a grease-pencil, and cutting it with a hatchet" type of operation.
In any case, the running voltage of your system being anywhere between 13 and 15.3 volts is not the reason your battery was discharged previously. You will need to find a different answer to that difficulty.
And in the meantime, do not spend a lot of time or money attempting to regulate your generator any more tightly than 13-15 volts or so. Your battery simply doesn't care.
In other words, with the information you've given, I do not see a problem with your charging system.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
George ,Thankyou.
Your information and advice has certainly put my mind at ease.
The voltage regulator is a direct replacement vibrating contact type.
My concern was borne through the previous posts where max voltages of 14.5V and lower engine RPM's for the generator warning lamp to extinguish had been stated as normal.
I understand the battery charging problem may be due to infrequent and short flights with to great electric load for the battery to recover from the starting operation.
If we had an allocated position in our large shared hangar a permanent charger as you have previously mentioned would be the solution .However as this is not possible I am considering getting a spare battery and keeping this on charge.
Thankyou
Bryce
Your information and advice has certainly put my mind at ease.
The voltage regulator is a direct replacement vibrating contact type.
My concern was borne through the previous posts where max voltages of 14.5V and lower engine RPM's for the generator warning lamp to extinguish had been stated as normal.
I understand the battery charging problem may be due to infrequent and short flights with to great electric load for the battery to recover from the starting operation.
If we had an allocated position in our large shared hangar a permanent charger as you have previously mentioned would be the solution .However as this is not possible I am considering getting a spare battery and keeping this on charge.
Thankyou
Bryce
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Dave Clark
- Posts: 894
- Joined: Mon Apr 22, 2002 6:25 pm
I have a Zeftronics regulater and digital readout on one of my UBG channels. My readings lock at 14.8v shortly after takeoff and I do 20 minute flights all Summer. I do have an alternator that charges at near idle and you might tend to be using a lot of power on older radios on the ground that just take the battery down a lot and the 20A generator can't replace it fast enough. George has some good points there but I think I'd monitor the battery fluid and if it seems to be boiling off a lot then try to adjust the charge down a bit.
Dave
N92CP ("Clark's Plane")
1953 C-180
N92CP ("Clark's Plane")
1953 C-180