the master switch no longer operate the relay battery

the master switch no longer operate the relay battery

Postby Paul Michel Fenouil » Sun May 06, 2012 10:40 pm

PA24-180
A faulty starter has created a short circuit: at startup I heard the relay battery (=battery solenoid) slamming multiple times, meaning a drop in voltage due to a large short circuit. The starter never turn.
Since this, the master switch is now inoperative; the relay battery no longer stick, I no longer hear it sticking as usual; I tested it and it works when I apply 12v .
I wonder if there is a breaker between the master switch and the solenoid battery. The faulty starter has created a short circuit, but this does not explain (for me) that the master switch no longer brings voltage to the relay battery.
I will receive a new solenoid battery but I doubt the problem will be resolved.
Somebody get an idea ?

Michel
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Re: the master switch no longer operate the relay battery

Postby Kristin Winter » Mon May 07, 2012 1:15 am

Check and see if you are getting voltage through the master circuit breaker.
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Re: the master switch no longer operate the relay battery

Postby Don Keller » Tue May 08, 2012 1:53 pm

Sounds like you may have burned a wire off probably at a loose or corroded conection. Do you have power to the master? Does the switch open and close when you flip it?

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Re: the master switch no longer operate the relay battery

Postby Paul Michel Fenouil » Tue May 15, 2012 2:41 pm

Thank you Kristin and Don;
The problem is finally solved: the cable connecting the negative battery to the airframe has aged, when you put the master switch on and switch on some other things (a landing light for example) the voltage between the battery negative and the airframe is 4 volts with about 8 amps of current, meaning the cable and its connections have an electrical resistance of 0.5 ohms which is a lot. The more you demand power (more amps), the more the connection to the airframe become faulty, increasing its resistivity .
Trying to start with a faulty starter revealed and amplified this bad connection to the airframe (faulty ground connection).
It's not easy to find because everything look normal.

Have nice flights

Michel
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Re: the master switch no longer operate the relay battery

Postby Jay » Tue May 15, 2012 4:59 pm

If you still have the original factory aluminum cables you may want to replace them with the Bogert copper cables. Your ground may not be the only bad connection that you have.

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Re: the master switch no longer operate the relay battery

Postby Paul Michel Fenouil » Tue May 15, 2012 5:14 pm

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Re: the master switch no longer operate the relay battery

Postby jeffrey aryan » Thu May 17, 2012 1:18 am

Paul,

Just a reminder.

If you every change out the aluminum cables for the copper ones and have a light weight starter such as the B&C. Make sure you tell the cable company about the light weight starter. They will add about an extra 6-8" inches to the cable for the shorter style housing and different placement of the cable.

While trying to copy the Hansmiester on my twin. I couldn't figure out why one cable was shorter. So I called the cable company and told them of my problem. They said, they have had the same problems in the past and have talked to the FAA. They now have approvals to add an extra length for the light weight staters. I was starting to detail my engines with cusion clamps instead of plastic tie wraps and re-route all the wires and cables into a neater apprearance. FWIW.

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