340 gauges

mwilke · Apr 22, 2018

I recently bought a 340 that was converted to 12 volt alternator. is it necessary to change ammeter and electric fuel gauge?

old · Apr 22, 2018

No problem with either one. Amp gauge does not car if it is 6 or 12 volts and same with the fuel gauge

Bob · Apr 22, 2018

Ammeters typically aren't rated for 6 or 12 volts, it doesn't matter.

Electric fuel gauges typically ARE. "old" says he has no issues running 6 Volt fuel gauges on 12 Volts, and he may be right, although I can't believe it does them any good to operate at double design voltage.

However, when I convert a 6 Volt system to 12 I install an electronic regulator to drop the voltage to the fuel gauge to 6 Volts nominal, actually more like 7 Volts.

There's dozens of "do it yourself" circuits out there to do this with a simple little integrated circuit voltage regulator, or they can be bought ready-made.

Another possible issue... if the system was originally (+) ground and has been converted to (-) ground some fuel gauges are not as accurate as before, after the conversion.

Below is ONE source from them ready-made.
Regulator at Speedway

Bob · Apr 22, 2018

Here's simple "homebrew" gauge voltage reducer...

<img src = "http://www.gondtc.com/~blweltin/Bob/6-12-VoltGaugeRegulator.JPG">

TJV · Apr 23, 2018

I do not think there should be any problem the 340 would have been 12 volt from new but would have been a generator and converting to an alternator wouldn't make Any difference for the gauges the only change made would have probably been to go from positive ground to negative ground

340 gauges

mwilke

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old

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Bob

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Bob

Well-known Member

TJV

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