Voltmeter

D

Don S

Senior Member
My voltmeter quit for the second time in a year , I got a new one today , but I am wondering if there should be a voltage controller of some sort to prevent voltage spikes , if that is what is causing the meters to fail ? I am using an alternator, but have done for many years with no issues.
Any ideas ?

Don S
 
I buy my voltmeter’s from Westach. Top quality stuff made in the US. I have many of their gauges and have yet to have a failure.
 
400A , not much choice unless you are a hot rodder . I wanted a 2” dia. Gauge with a black face , to match my temp gauge . Lots of larger more fancy ones ,but not suitable. Also I don’t buy anything on line .
Don S
 
You could put a fairly large capacitor across the voltmeter that would short out large voltage spikes. An ignition condensor would be large enough and they are readily available.
 
Most modern alternators have a voltage regulator built into them. Perhaps yours is failing?
 
Nkaminar and Willh good suggestions, nkaminar , the condenser would be on the hot line like a fuse ? I will have my alternator checked for voltage spikes

Thanks Don S
 
Don S said:
Nkaminar and Willh good suggestions, nkaminar , the condenser would be on the hot line like a fuse ? I will have my alternator checked for voltage spikes

Thanks Don S
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The condenser should be connected to the positive input to the meter and the other end to ground.
 
jeepguy1948 said:
I buy my voltmeter’s from Westach. Top quality stuff made in the US. I have many of their gauges and have yet to have a failure.
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Jeepguy, I have one of the Westach 20-0-20 ammeter’s in my car and it works and looks great. They are essentially hand built and the folks there are really helpful and knowledgeable.
 
KMBeers said:
Jeepguy, I have one of the Westach 20-0-20 ammeter’s in my car and it works and looks great. They are essentially hand built and the folks there are really helpful and knowledgeable.
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Thanks for the information, I just ordered one of these for my car!
 
I have a very nice Westach ammeter I have yet to use yet. It even has a lighted face. Not cheap tho. Some day...

586890
 

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I found this suggestion on the internet: To protect a DC voltmeter in an automotive environment, install a fast-blow inline fuse to prevent over-current, and place a Transient Voltage Suppression (TVS) diode across the power lines to absorb high-voltage transients. A Transient Voltage Suppression (TVS) diode is a specialized electronic component designed to protect sensitive circuits from sudden or temporary voltage spikes (transients). They react in picoseconds to clamp excess voltage to safe levels and shunt it away from your components. A TVS is placed in parallel to the voltmeter.
 
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Bob, thanks for the info, could you provide a sketch of how this works, plus part numbers for the parts mentioned ? Modern electrical stuff is not my forte

Don S
 
Bob , thanks for your information. Any chance you could do a sketch for me to help understand ,with part numbers that may be needed. Modern electrical stuff jargon is not my strong suit
Don S
 
To protect a car voltmeter from severe electrical transients, select a unidirectional or bidirectional AEC-Q101 qualified TVS diode with a reverse standoff voltage of at least 24V and a breakdown voltage around 33V - 36V. This should work for 6V & 12V systems. Connect the diode across the voltmeter's terminals (in parallel). The diode is polarity sensitive, so obey its polarity markings.
By the way, a TVS Diode is very inexpensive.
 
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The repop amp gauges should be "fixed" before they are installed. Paul Shinn did a video on opening them up and soldering them internally for a positive connection.
 
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