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Low Voltage or Error w/ JPI EDM960?

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Joined
Jan 20, 2022
Messages
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10
1979 Seneca II

I recently had these voltage spikes and low voltage reading after cold starts for approximately::10mins after each start.

As soon as I get airborne, voltage seems to be in normal range, then proceeds to climb and on a rare occasion, exceeds 15 volts.

My mechanic troubleshoot the issue, ran both engines and indicates the alternators are each within range in all rpm ranges.

I have turned off the left and right alternator at altitude to determine the issues and this is what I saw.

Right alternator sw off, the volt meter drops to 13.9volts.

Both alternator switches back on, bolts increase to 14.8 volts and occasionally goes above 15 volts.

Left alternator sw off, the volt meter drops to 12.5 volts.

A year ago, we replaced a radio master relay in the frwd nose gear compartment and again about two weeks ago. The relay was burnt and caused me to loose voltage irregularly while at idle rpm. See attached picture.

My mechanic indicates the older relays may have been weak, and with a new one it should last a normal lifetime, but I’m very curious we have a ground issue or another contributing issue with wiring, maybe a bus bar connection issue or with the EDM960?

Thank you in advance. Appreciate your input.
 

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