Electrical problem

Gregor, I would like to help you, but I'm going to have to ask some questions first to understand the problem.

1. Do you have a wiring diagram for this aircraft that you can post here?

2. Is the battery master switch turned on (closed) when this problem happens?

3. In Picture 1, the device that you circled is a 30A circuit breaker, not a switch.  Does the problem occur any time this circuit breaker is closed, or is there a switch somewhere else?

4. You said that a fuse blows.  Are you talking about the 30A circuit breaker in Picture 1, or is there a fuse somewhere else?  If it is the 30A circuit breaker, does it pop out as soon as you push it in?

5. You said, "...power goes directly to the starter."  Do you mean that the starter starts to turn the engine?

6. In Picture 2, it appears that you have disconnected the red wire coming from the OVP 15.2 (the battery positive wire) from a contactor on the firewall.  This is the battery contactor, correct?

For anyone else who wants to help, here is the wiring diagram for the Schicke OVP 15.2 unit.  It appears to be a relay with some control electronics that senses high voltage at the battery (>15.2V?) and opens the relay to stop charging.  So, overvoltage protection for the battery only.  Interesting device... perhaps intended to prevent the BMS from disconnecting the battery from the bus by never letting it see an overvoltage condition?

The unit marked "GR6" is a Schicke Electronics voltage regulator.

"gelb" = yellow / "blau" = blue / "rot" = red / "hauptschalter" = main switch / "starterrelais" = starter relay / "generatorsicherung" = generator fuse

Hi Gregor,

Assuming the dark grey tube in the top-right of picture 2 is the cylinder 4 exhaust elbow, it looks to me like the terminal post with the number 2 is the output of the starter relay/contactor. The only wire connected to it in the picture looks like it runs in the direction of the starter motor.

Based on the description and diagram that Eric posted, (thanks, Eric!) if the disconnected ring terminal in picture 2 were to be connected to the terminal post on the right (number 2), the output of the regulator would go directly to the starter motor - until the the generator circuit breaker trips. This would probably result in symptoms something like what you are describing.

I would suggest to try connecting the red wire from the OVP 15,2 unit directly to the battery to see if that solves your problem.

Hi Eric

Thank for your help😊

1. I have attached the wiring diagram.

2. The battery master switch is not turned on when the problem happens.

3. I know that it is a circuit breaker, sorry for calling it a switch, but Flight Design use it like a switch. The problem occur any time this circuit        breaker is closed, this is the only "switch" mounted.

4. There is mounted a 25A fuse on the red wire from the OVP yhat blows

5. The red wire from the OVP is mounted to number 2 ( on picture 2 ) together with the wire which goes directly to the starter from the starter relay.

6. I  have disconnected the red wire to see if that solved the problem, and i did. But now i am confused if the problem is the OVP or could the problem be elsewhere ?

Hi Tim.

Thanks for your reply 😊

I will try to mount the red wire directly to the + ont the battery.

Eric i forgot to wright to point 5 that when i push the circuit breaker, there is comming 12v out of the red wire from the OVP.

and that tryes to turn the starter as it not should and then the fuse blows. 

So the probleme is why there is comming power on the red wire ?

I hope you understand what i mean ? Its not easy for me to explain in English 😊