Voltage drops

Vlad · #1 06-10-2011, 01:36 PM

I admit I am electrically challenged

My electrical schematic is simpler then one of half century old Cub. No glass in the panel not much load. Wired per Vans drawings, new B&C 35A alternator and LR3 external regulator. Wired per their instructions all options trimmed.

The voltage drops when I switch alt. field ON, engine is running. There is a barely noticed beep in headset (SL40 on) and voltage slowly goes down till needle pegs. Vans voltmeter, only two wires out. What could cause that? Honestly I didn't dig deep enough in theory but checked all the wiring and ground. Email to B&C was not answered.

Momentarily I saw increase in voltage to 14V but no more.

jdeas · #2 06-10-2011, 04:17 PM

Check the mains voltage across the battery. I would be surprised if it really is zero volts or the battery would be dead. If the mains really isn't at zero then check your gauges.

AltonD · #3 06-10-2011, 05:42 PM

Vlad, check the voltage to the field, pin 4 on the regulator. The fieled will pull quite a bit of current (5-6 amps). If you are seeing voltage, I would pull the alternator, take it to your local autozone-aviation store and have it tested.
What are you using for a current limiter on the alternator? I would check the voltage across this too. 14 volts and it is open.

N15JB · #4 06-10-2011, 10:09 PM

Vlad,

Get the trouble shooting page for your regulator, available on the B & C web site. It will walk you through a diagnostic tree for each pin, and tell you what the problem is if any pin is off spec. I just went through this for my LR3C.

Jim Berry
RV10

PCHunt · #5 06-10-2011, 11:36 PM

You might try taking the battery temp sensor out of the circuit, and see what happens.

Vlad · #6 06-25-2011, 04:40 PM

Quote:

Originally Posted by N15JB

Vlad,

Get the trouble shooting page for your regulator, available on the B & C web site. It will walk you through a diagnostic tree for each pin, and tell you what the problem is if any pin is off spec. I just went through this for my LR3C.

Jim Berry
RV10

Jim I did that. All voltages and differences between them normal. The main suspect is the voltmeter. Will hook up the portable and check it in couple days. Everything is brand new - PC680 battery, B&C 40 amp alternator and external regulator. No heat sensor, no low voltage hook up.

Vlad · #7 06-26-2011, 09:24 AM

Defective voltmeter and B&C tech was right. Thanks Bill

Taped another foreign made device to iPad mount and taxied around with the rig

. Everything works time to order a new voltmeter.

turbo · #8 06-26-2011, 06:20 PM

v, sounds like the fun is starting. what airport are you flying out of? will be nice to meet up some time soon.

Vlad · #9 06-26-2011, 06:26 PM

Ed I am out of Princeton/Rocky Hill 39N. Stop by any time if you are in the area. Cousin is trying to talk me into visiting you guys up north for breakfast some time.

turbo · #10 06-27-2011, 04:28 AM

v, i heard sky manor is the place to go in your area. will that 9 make it there?