Post by lollygagger on Jul 8, 2017 15:38:31 GMT
Not a boat but an old vehicle fuel gauge.
Fuel gauge reads too high, it measures resistance as an arm sweeps over a coil on the sender, or rather it measures current changed by the resistance at a stabilised voltage...I think.
This is what I've found on the internet...
"This one is a zener diode shunt regulator design. 12V input is fed thru a series resistance in the form of a small incandescent lamp to a 5.2V Zener diode. The lamp provides some regulation in itself since incandescent filaments vary in resistance dramatically as they heat up. If the 12V supply increases (as when battery is charging), the lamp gets slightly brighter and its resistance goes up, decreasing the output voltage. The Zener then performs the remainder of fine regulation required."
Mine is outputting 7.6V and the reading on the gauge is correspondingly high so I'm thinking it must be the problem?
Any bodges or am I looking for a replacement(30 ---ing quid and out of stock!).
The resistance should be in the order of 10 to 80 ohms if that helps.
Fuel gauge reads too high, it measures resistance as an arm sweeps over a coil on the sender, or rather it measures current changed by the resistance at a stabilised voltage...I think.
This is what I've found on the internet...
"This one is a zener diode shunt regulator design. 12V input is fed thru a series resistance in the form of a small incandescent lamp to a 5.2V Zener diode. The lamp provides some regulation in itself since incandescent filaments vary in resistance dramatically as they heat up. If the 12V supply increases (as when battery is charging), the lamp gets slightly brighter and its resistance goes up, decreasing the output voltage. The Zener then performs the remainder of fine regulation required."
Mine is outputting 7.6V and the reading on the gauge is correspondingly high so I'm thinking it must be the problem?
Any bodges or am I looking for a replacement(30 ---ing quid and out of stock!).
The resistance should be in the order of 10 to 80 ohms if that helps.
The Angel's share 