Volt & amp instrument

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tazin river
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Volt & amp instrument

Post by tazin river »

I had one of those digital volt and amp meter instrument installed
In ouR Cessna 180. The volt meter is registering fine between 14.2 and 14.4 but the amp meter
Is showing zero or minus one or two steady!

The alternator is definitely charging well. Could it be that the amp
Meter part was not installed properly? Bad connection? Faulty gauge?

Advise! Thanks.
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ahramin
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Re: Volt & amp instrument

Post by ahramin »

If I recall correctly the ammeters in Cessna aircraft read current to and from the battery, not the alternator, which means after start you should see some current flowing to the battery which quickly goes close to zero as it is topped up.

Wouldn't the people you paid to install it be able to answer this question though?
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PilotDAR
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Re: Volt & amp instrument

Post by PilotDAR »

Using the very popular Electronics International VA-1 as an example, they can be installed either of two ways, each producing different readings. Read the instructions, it is well explained (for EI anyway). To determine which way yours is wired note the current indicated when there is a decent draw (like landing light, other than LED/HID) with the engine (alternator) running, then note it again with the alternator not producing current (either turn it off, or shut down the engine, if it's not a separate switch).

With understanding the instructions, it should all make sense...
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Strega
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Re: Volt & amp instrument

Post by Strega »

tazin river wrote:I had one of those digital volt and amp meter instrument installed
In ouR Cessna 180. The volt meter is registering fine between 14.2 and 14.4 but the amp meter
Is showing zero or minus one or two steady!

The alternator is definitely charging well. Could it be that the amp
Meter part was not installed properly? Bad connection? Faulty gauge?

Advise! Thanks.
If you turn off the alternator, does it read positive current? (especially with electrical consumers on)
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tazin river
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Re: Volt & amp instrument

Post by tazin river »

When engine turned off I do get positive reading! Reverse connection?

Thanks for helping folks
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GyvAir
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Re: Volt & amp instrument

Post by GyvAir »

tazin river wrote:When engine turned off I do get positive reading! Reverse connection?
If it is wired into the battery lead, then yes, that sounds like the problem. (If in the alternator lead, I have no 3000 mile guesses)
If that's the case, there should be some red faces at the shop you had it installed at.

13. Ground Test:

VA-1A Installed in the Battery Lead

- With the master on and the engine off, the discharge light should be on, the Volts position will read 11.9 to 12.5 volts (23.8 to 25 volts for a 24 volt system) and the Amps position should read -2.0 to -10.0 amps depending on your current load for the aircraft. Changing the load
will change the amps reading.
With the master on and the engine on, all lights will be off, the Volts position will read 13.2 to 14.8 volts (26.4 to 29.6 for a 24 volt system) and the Amps position will read 5.0 to 15.0 amps and reducing rapidly (shows battery charging current). Changing the load will not change the amps reading. See the operating section of this manual for further details.

VA-1A Installed in the Alternator Lead

- With the master on and the engine off, the discharging light will be on, the Volts position will read 11.9 to 12.5 volts (23.8 to 25 volts for a 24 volt system) and the Amps position should read 0.0 amps +/- .2 amps. Changing the load will not change the amps reading.

With the master on and the engine on, all lights will be off, the Volts position will read 13.2 to 14.8 volts (26.4 to 29.6 for a 24 volt system) and the Amps position will read 5.0 to 25.0 amps and reducing rapidly (shows battery charging current plus load current for the aircraft). Changing the load will change the amps reading. See the operating section of this manual for further details.
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tazin river
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Re: Volt & amp instrument

Post by tazin river »

Thanks folks.

This is really helpful. My AME is back in town next week and we'll take another look at the connections....

Cheers
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